- Email: [email protected]
2006
Food Chemistry 121 (2010) 672–681
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Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Lipid composition of Australian pork cuts 2005/2006 Andrew J. Sinclair a, Sebastian Barone b, Tim Stobaus b, Ron Tume c, Shane Beilken c, Warren Müller d, Judy Cunningham e, Jane A. Barnes f, Heather Greenfield g,h,* a
School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood VIC 3125, Australia National Measurement Institute, 1/153 Bertie Street, Port Melbourne, VIC 3207, Australia c Food Science Australia, P.O. Box 3312, Tingalpa DC QLD 4173, Australia d CSIRO Mathematical and Information Sciences, G.P.O. Box 664, Canberra ACT 2601, Australia e Food Standards Australia New Zealand, P.O. Box 7186, Canberra BC ACT 2610, Australia f Foodsense, P.O. Box 551, Mosman NSW 2088, Australia g Faculty of Veterinary Science, University of Sydney, NSW 2006, Australia h Food Science and Technology, School of Chemical Sciences and Engineering, University of New South Wales, Sydney, NSW 2052, Australia b
a r t i c l e
i n f o
Article history: Received 3 July 2009 Received in revised form 19 October 2009 Accepted 24 December 2009
Keywords: Pork Fatty acids Cholesterol Australia
a b s t r a c t A study of the cholesterol content and fatty acid composition of fresh retail Australian pork was undertaken to determine whether new breeding, feeding and processing methods had resulted in any compositional changes in fresh pork in the market place since surveys undertaken in previous decades. Samples of 13 popular pork cuts were purchased from randomly selected supermarkets and butchers’ stores in urban areas across the socioeconomic scale in three States of Australia, and analysed, separable fat and separable lean, in late 2005 and early 2006. Variability was low across States for saturated and monounsaturated fatty acids, but more pronounced for polyunsaturated acids. The separable lean portions of all pork cuts contained levels of n-3 fatty acids and conjugated linoleic acid (C18:1c9t11) in measurable but not nutritionally claimable amounts, whilst total trans fatty acid levels were very low. There appeared to be some differences in fatty acid composition across States that may have resulted from feeding method. Cholesterol contents were similar to levels in the 80s and 90s for separable lean pork tissue, but presently are lower for separable fat tissue than for separable lean. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction The Australian pork industry contributed $2.9 billion Australian dollars to the national economy in 2006–07. About 15–20% of pigmeat production is exported annually, to markets in Asia and Australasia, with the figure for 2006–07 at 39,100 tonnes (Department of Agriculture & Forestry, 2007). Analytical data for the nutrient composition of Australian fresh pork as available for purchase by consumers were published for 1983–84 using samples of six cuts collected from retail outlets in Sydney suburbs across the socioeconomic scale (Hutchison, Greenfield, & Wills, 1987) and subsequently updated a decade later in 1994 with analysis of samples, this time of 13 cuts, again gathered from retail outlets in Sydney suburbs (Barnes, Lewis, & Buick, 1996). In both of these studies the lipid analyses were performed only on a single composite sample for each cut. In the 2000s the move has been to purchase com-
* Corresponding author. Address: Food Science and Technology, School of Chemical Sciences and Engineering, University of New South Wales, Sydney, NSW 2052, Australia. Tel.: +61 293987695. E-mail address: heather.greenfi[email protected] (H. Greenfield). 0308-8146/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2009.12.096
modities for nutritional analysis more widely across Australia, as exemplified by a study of Australian red meats (Cobiac, Droulez, Leppard, & Lewis, 2003). Further, due to greater awareness of the nutritional significance of long-chain n-3 fatty acids, conjugated linoleic acid and trans-fatty acids to consumers, there was a need to carry out more detailed analyses of these lipid components in fresh retail pork using capillary gas chromatography. Therefore Australian Pork Limited (APL) commissioned a national study of fresh retail pork as available to Australian consumers in the early 21st century. This study was to provide gross compositional and comprehensive nutrient data that would reflect the product as nationally available, for product nutrition labelling, for promotional purposes and for provision of data to the ongoing national food composition database (NUTTAB) compiled by (Food Standards Australia New Zealand, 2007) and used for national public health nutrition, dietetic and food regulation purposes. A new study was additionally necessary as there had been considerable changes in rearing, feeding and genetics of pigs over the previous decade, with more uniformity of these factors nationwide and the production of larger, leaner pigs (Hermesch, 2006). The establishment of INFOODS in 1984 (FAO, 2009), recognised the importance of the production and sharing of good quality food composition data
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internationally, particularly for public health nutrition and trade purposes. Accordingly INFOODS introduced internationally agreed guidelines for methods for producing, expressing and sharing such data in compatible formats. The specific objectives of the present study were: to examine the variation in content of these lipid components from pork samples from different parts of the country; to determine if there had been any changes in pork cholesterol and fatty acid composition in the last decade compared with previous assessments; to compare the lipid composition of pork with recent data for Australian red meats; to compare the fresh Australian pork product with that of other industrialised countries; and, to provide pork lipid compositional data for inclusion in current Australian food composition tables (NUTTAB) maintained by FSANZ.
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one of the samples (selected at random) was dissected and measured for gross composition. Samples were held at 1–2°C before and during handling, and kept covered in closed polyethylene bags to minimise evaporation of moisture. As soon as dissection had been completed, samples were re-bagged and returned to a cold room at 1–2°C. All cuts were photographed on arrival and during laboratory handling. 2.3. Cooking methods All cuts were analysed for cholesterol as separable lean and separable fat, in the raw state and in the cooked state. Cooking methods were as specified by APL home economists to reflect household practice then adapted for the available equipment. Details of cooking methods are given in Müller et al. (2009).
2. Materials and methods 2.4. Preparation of analytical homogenates 2.1. General approach The general approach to this overall study has been described elsewhere (Greenfield et al., 2008). 2.2. Sampling, pork cuts and collection procedures The national sampling scheme, nomination of cuts, and cut collection procedures are described in detail by Müller et al. (2009) along with results for gross composition analyses. The overall sampling scheme for each pork cut was:
3 States 3 SEC 2 replicate suburbs 2 retailer types 2 conditions ðraw; cookedÞ ¼ 72 samples ðpurchasesÞ where, State = Australian State; retailer type = butcher/supermarket; SEC = socioeconomic status of suburb (high, medium, low). The 13 cuts which were advised to be the more popular consumer cuts and therefore selected were: loin chop, loin steak, fillet, rump steak, round steak, topside steak, silverside steak, diced pork, pork strips, pork mince, loin roast, round (mini) roast, scotch (neck) roast. One cut, the loin chop, was studied in more detail across all three States, in order to provide additional data on compositional variability. Sample collection and handling generally followed international guidelines issued by Food and Agriculture Organisation/International Network of Food Data Systems (Greenfield & Southgate, 2003). Pork loin chop samples were collected in December 2005, and the other cuts progressively from February to May 2006. For the 13 cuts the number of actual purchases was 911 instead of the planned 936 because of a small number of cuts that were unavailable on the day of collection. Sample collection was organised by APL representatives in each of the three States and shoppers were commissioned to purchase duplicate samples (e.g. two pork roasts or 2 kg of smaller cuts) anonymously from each nominated retail outlet. Shoppers were instructed not to specify whether trimmed or untrimmed cuts were desired. The meat samples were packed and freighted chilled to the Food Science Australia (FSA) laboratory in Queensland by air from Melbourne, Victoria and Perth, Western Australia and by road from Brisbane. Meat temperatures were checked on arrival at FSA and all samples were stored at 1–2 °C until required for processing, either immediately or later on the same day. Where incorrect cuts had been supplied attempts were made to obtain replacements, or were later designated as missing values along with those that were not available. The duplicate samples purchased for each cut were randomly allocated to either raw or cooked treatment. For purchases consisting of several samples (e.g. loin chop) only
For each cut except loin chops, four analytical homogenates were formed from the individual purchases, cooked and raw, fat and lean, as homogenised composites. For loin chops, 24 analytical homogenates were formed; 3 States 2 replicates 4 portions (lean/fat raw/cooked). The two replicates were obtained by combining the two retailer types from one randomly selected set of a high, a medium and a low SEC area as one composite, and the remaining high, medium and low SEC areas as a second composite. The dissected meat was weighed and aliquot samples were allocated for aggregation according to the experimental design for the particular cut. The aggregate meat sample was coarsely cut, hand mixed and minced through a meat mincer (IRCEM Srl Tritacarne Type I-E 22, 240V, Italy) using a single blade and a 4 mm mincing plate. The samples were then recombined and minced again to attain adequate homogeneity. Contact with metal was minimised wherever possible. The mincer was dismantled and washed after each sample was minced to eliminate cross-contamination between samples. Temperatures were maintained at 1–2 °C throughout preparation of analytical homogenates. Initially, a number of individual samples were assessed by measuring homogeneity by the reproducibility of their moisture contents to establish the degree of mixing required. Samples within a 2% moisture range were assessed as sufficiently homogenised e.g. 75% + 2%. The samples were then packed in plastic jars and stored chilled or frozen until required for further evaluation. The four (4) composite samples that were obtained for each of the cuts were raw lean, cooked lean, raw fat and cooked fat. For some cuts, only raw lean and cooked lean data were required due to the absence of separable fat on cuts such as fillets. 2.5. Transport of analytical homogenates Samples were coded and sent frozen for the analyses of moisture, fat, cholesterol and fatty acids to National Measurement Institute (NMI) in Melbourne. All samples were freighted in insulated containers by overnight courier on the day following preparation. Samples were vacuum-packed and stored at NMI in a 80 °C freezer. 2.6. Variability study of lipid composition of pork loin chop All 24 composites of loin chop were analysed, separable lean and separable fat, for cholesterol (raw and cooked) and fatty acids (raw only). The cut collection and gross composition work was carried out in December 2005. The analytical work was completed in October 2006.
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2.7. Representative study of lipid composition of 12 other pork cuts 2.7.1. Cholesterol The remaining 12 cuts were analysed as 34 national composites (for 5 cuts: national duplicates 4 portions (lean/fat, raw/cooked), total = 20; for 7 cuts: national duplicates 2 portions (lean only or lean + fat mixed, raw/cooked), total = 14). 2.7.2. Fatty acids The remaining 12 cuts were analysed as 17 national composites (for 5 cuts: 1 national composite 2 portions, lean/fat, raw only, total = 10; for 7 cuts: 1 national composite 1 portion, lean only or lean + fat mixed, raw only, total = 7). The cut collection and gross composition work was done from February to May 2006. The nutrient analytical work was completed in October 2006.
acid present was determined by normalisation of the peak areas obtained. i.e. peak area (individual acid) divided by the sum of peak areas and multiplied by 100 to give the percentage proportion of the acid. For specified fatty acids, e.g. C18:3n-3, this percentage proportion was then multiplied by the total fat present in the sample, as determined by Soxhlet fat extraction, to give a mass/mass value (mg/100 g) of the individual fatty acid in the sample.
Table 1 Moisture, fat and cholesterol composition for 13 pork cuts, separable lean and separable fat, raw and cooked, per 100 g. Fat (g)a
Cholesterol (mg)
74.1 ± 0.7 63.3 ± 0.5 23.8 ± 4.9 21.3 ± 2.4
1.75 ± 0.21 4.47 ± 0.38 69.2 ± 4.6 70.7 ± 3.1
48 ± 17 67 ± 16 39 ± 10 41 ± 10
Loin steak or medallionc Lean, raw 75.5 Lean, cooked 67.7 Fat, raw 26.4 Fat, cooked 30.8
1.6 3.5 68.5 55.5
48 63 38 46
Fillet c Lean, raw Lean, cooked
75.2 68.9
1.1 2.2
47 56
Rump steakc Lean, raw Lean, cooked Fat, raw Fat, cooked
73.7 68.3 27.1 34.9
2.1 3.8 66.4 53.7
45 57 38 32
Round steakc Lean, raw Lean, cooked
75.6 69.3
1.1 1.7
46 62
Topside steakc Lean, raw Lean, cooked
75.1 69.3
2.0 2.3
43 52
Silverside steakc Lean, raw Lean, cooked
75.4 68.8
2.0 3.0
60 63
Diced porkc Raw Cooked
75.2 65.7
3.1 3.1
69 82
Pork stripsc Raw Cooked
75.4 66.4
2.3 2.5
50 59
Pork mincec Raw Cooked
70.6 64.8
9.4 10.2
54 57
Loin roastc Lean, raw Lean, cooked Fat, raw Fat, cooked
74.3 61.4 19.3 26.1
2.2 8.6 77.1 67.0
46 57 38 33
Round (mini) roastc Lean, raw Lean, cooked Fat, raw Fat, cooked
75.5 64.5 45.3 41.4
1.1 2.5 44.6 45.5
68 89 76 65
Scotch roastc Lean, raw Lean, cooked Fat, raw Fat, cooked
72.6 58.9 38.1 39.8
7.6 12.0 52.5 50.5
50 74 48 46
b
Loin chop Lean, raw Lean, cooked Fat, raw Fat, cooked
2.8. Methods of analysis Methods of analysis were agreed in terms of availability and appropriateness for pork, and in terms of the expected ranges of nutrient levels in this commodity. Methods for moisture and fat, previously determined on these samples, appear in the reference to the earlier publication from this study for macro- and micronutrients (Greenfield et al., 2009). 2.8.1. Cholesterol The method used was AOAC gas chromatographic method No. 976.26 (AOAC International. 2005/2006), using a 12 m BP1 capillary column and determination by flame ionisation detector. Limit of quantification was 0.1 mg/100 g. Analyses were performed in duplicate. 2.8.2. Fatty acids Fat was extracted from meat samples (approximately 10 g) using a chloroform: methanol (2:1) extraction process (Bligh & Dyer, 1959). The extracted fat was then transesterified using methanolic sodium methoxide solution, subsequently treated with sulphuric acid in methanol to esterify the free acids (Badings & De Jong, 1983; Christie, 1993) and then re-extracted with hexane. These extracts were analysed for fatty acids using an Agilent 6890 gas chromatograph with flame ionisation detector (Agilent Technologies Australia Pty Ltd., Forest Hill Victoria 3131). Separation of the methyl esters of C4:0 to C24:3 was effected by means of a 100 m polysiloxane bis-cyanopropyl capillary column (Supelco SP™-2560, L I.D. 100 m 0.25 mm, df 0.20 lm) at an initial oven temperature of 90 °C for 1.0 min, then ramped at a rate of 30 °C/min up to 135 °C, then ramped up to a final temperature of 240 °C at 2.5 °C/min, then held for 5.5 min. Total run time was 50 min. The carrier gas was hydrogen set at 1.2 mL per minute at a pressure of 149 kPa in constant flow mode. Identification, integration and calculation of the individual fatty acid concentrations were performed using Agilent Chemstation software against known standards. Results for the individual fatty acids were expressed as a relative percentage of the total fatty acid content (limit of quantification, 0.1%) or, in the case of specific acids, mg/100 g food (limit of quantification, 1 mg/100 g. Samples were analysed as raw only, with single determinations. Each analytical batch was required to conform to a range of quality criteria, including; satisfactory recoveries for in-house control materials and at least one duplicate analysis with results within 10% of the duplicate mean. Also included was a satisfactory determination of the referenced fatty acids for NIST CRM 1546 (meat homogenate), this was performed quantitatively as mg/100 g of the NIST material. The individual fatty acids were determined as a proportion of the total fatty acids present. The proportion of each fatty
Moisture (g)a
Cut
a
Data from Greenfield et al. (2009). Results are means ± standard deviation for two composites from each of three Australian States (6 analytical samples), duplicate determinations. c Results are means for two composites from three Australian States (2 analytical samples), duplicate determinations. b
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2.9. Apparent retention of nutrients
2.11. Data scrutiny
Apparent nutrient retention (%) was calculated as: nutrient content per g of cooked food (dry basis)/nutrient content per g of raw food (dry basis) 100 (Murphy, Criner, & Gray, 1975).
All authors scrutinised the analytical data on receipt. Further scrutiny, including integrity checks, of the complete data sets was performed by three of the authors, Barnes, Cunningham and Greenfield. All scrutineers compiled their own independent lists of queries. After agreement between the scrutineers reached by teleconference, a consolidated list of queries and, in some cases, requests for reanalyses was sent to NMI, Melbourne. Further scrutiny was done, including of repeated analytical results, until all scrutineers were satisfied with the reliability of the analytical data.
2.10. Quality control Cholesterol analyses were performed in duplicate whilst fatty acid analyses were single determinations after preliminary results for loin chop showed mostly only 0–4% differences between duplicate determinations. Quality control procedures for all analyses included the use of National Institute of Standards and Technology (NIST) Standard Reference Material 1546 Meat Homogenate, in-house reference materials (e.g. butter fat, cod liver oil and canola oil for the fatty acid determinations), precision of replicates, recoveries of standards, use of blanks and other routine quality control checks, as appropriate.
2.12. Statistical analyses For each loin chop variable a three-way analysis of variance was performed; 3 States 2 types (lean/fat) 2 cooking categories (cooked/raw). A split plot-type analysis was performed as each of the six States replicates was regarded as a main plot and was split for the four types cooking categories. Variation be-
Table 2 Saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) acid composition of pork loin chop, raw, per cent total fatty acidsa. State/SFA
C14:0
C16:0
C17:0
C18:0
C20:0
C22:0
Total SFA
QLD Lean, raw Fat, raw
1.35 1.40
25.2 24.7
0.40 0.60
12.4 13.3
<0.1b 0.10
0.10 <0.1
39.4 40.2
VIC Lean, raw Fat, raw
1.10 1.45
24.1 26.7
0.30 0.45
12.6 15.2
<0.1 0.20
0.15 <0.1
38.4 44.0
WA Lean, raw Fat, raw
1.15 1.30
22.7 24.7
0.45 0.65
12.0 13.3
<0.1 0.10
0.10 <0.1
36.4 40.1
National mean ± SDc Lean, raw Fat, raw State/MUFA
1.20 ± 0.13 1.38 ± 0.12 C16:1
24.0 ± 1.2 25.4 ± 1.1 C17:1
0.38 ± 0.10 0.57 ± 0.16 C18:1
12.3 ± 0.4 13.9 ± 1.0 C18:1,9t
<0.1 0.13 ± 0.05 C20:1
0.12 ± 0.03 <0.1 C24:1
38.1 ± 1.4 41.4 ± 2.0 Total MUFA
QLD Lean, raw Fat, raw
3.50 2.45
0.45 <0.1
40.6 44.3
0.45 0.50
0.70 0.85
<0.1 <0.1
45.8 48.1
VIC Lean, raw Fat, raw
3.20 2.60
0.60 <0.1
41.4 44.2
0.35 0.55
0.65 0.90
<0.1 <0.1
46.2 48.2
WA Lean, raw Fat, raw
2.65 2.20
0.60 <0.1
40.0 45.6
0.40 0.60
0.70 0.95
<0.1 0.2
44.2 49.6
National mean ± SDc Lean, raw Fat, raw
3.12 ± 0.46 2.42 ± 0.28
0.55 ± 0.10 <0.1
40.7 ± 1.6 44.7 ± 0.8
0.40 ± 0.06 0.55 ± 0.14
0.68 ± 0.04 0.90 ± 0.06
<0.1 <0.1
45.4 ± 1.9 48.6 ± 1.0
State/PUFA
C18:2n-6
C18: 3n-3
C20:2n-6
C20:3n-6
C20:3n-3
C20:4n-6
C20:5n-3
C22:4n-6
Total PUFA
QLD Lean, raw Fat, raw
9.6 10.3
0.40 0.60
0.30 0.45
0.40 <0.1
<0.1 <0.1
2.70 0.15
0.20 <0.1
0.40 <0.1
14.7 11.4
VIC Lean, raw Fat, raw
9.5 6.9
0.35 0.40
0.30 0.40
0.45 <0.1
<0.1 <0.1
3.15 <0.1
0.25 <0.1
0.45 <0.1
15.3 7.7
WA Lean, raw Fat, raw
13.2 9.0
0.75 0.60
0.45 0.55
0.35 <0.1
0.1 <0.1
2.65 <0.1
0.20 <0.1
0.35 <0.1
18.7 10.2
0.50 ± 0.20 0.53 ± 0.12
0.35 ± 0.08 0.47 ± 0.08
0.40 ± 0.06 <0.1
<0.1 <0.1
2.83 ± 0.41 <0.1
0.22 ± 0.04 <0.1
0.40 ± 0.06 <0.1
16.2 ± 2.5 9.7 ± 1.7
National mean ± SDc Lean, raw 10.8 ± 2.1 Fat, raw 8.7 ± 1.6
QLD, Queensland; VIC, Victoria; WA, Western Australia. a Results are shown as means for duplicate composites for each of three Australian States (6 analytical samples), single determinations. b Limit of quantification 0.1%. c National means ± standard deviation (6 analytical samples).
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tween duplicate readings (cholesterol only) was obtained as a final split within the analysis, which enabled the reliability of the analytical method to be assessed. For some fatty acids measurements on lean and fat samples for each cut were analysed separately, as the values for lean and fat were distinctly different and it was inappropriate to use the single analysis. A number of fatty acids had contents below the limit of quantification in all or some of the samples, so no statistical analysis could be performed in those cases. In all cases the key assumptions of analysis of variance, namely homogeneity of variation across the range of values and normally distributed error terms, were checked and found to hold, so no variables required transformation before analysis. The package GenStat for Windows (2007) was used for these analyses. As composites for all the other cuts were formed over all replicate samples, no estimates of variability could be obtained and results are expressed as means over duplicate deter-
minations for cholesterol or as the value from the single determination for fatty acids. 3. Results 3.1. Quality control results for cholesterol and fatty acid analyses The variance ratio for the cholesterol analyses was 1.32 (p = 0.278), meaning that variation between analytical duplicates was similar to variation between test pork composite samples. This reflected poor precision for the performance of the analytical method. Spike recoveries of pure standard which averaged 90% were also somewhat unsatisfactory. However, the laboratory quality control report for the reference material (NIST 1546, Meat Homogenate) showed satisfactory recoveries at a mean of 0.745 g/kg homogenate of the certified content of cholesterol
Table 3 Specific fatty acid composition of pork cuts, separable lean and separable fat, raw, mg/100 g. Cut
C18:2c9t11 (conjugated linoleic acid)
C18:1t9
C20:4n-6
C18:3n-3 (ALA)
C20:5n-3 (EPA)
C22:5n-3 (DPA)
C22:6n-3 (DHA)
Loin chopa QLD Lean Fat
9.4 154
7.5 357
48.1 95.6
7.4 421
<0.1b 32
7.2 43
6.5 51
VIC Lean Fat
3.6 220
6.6 331
61.8 54.7
7.2 282
<0.1 10
9.8 23
6.7 25
WA Lean Fat
4.2 183
8.0 444
45.6 63.2
13.2 459
<0.1 45
7.9 30
5.5 25
National mean ± SDc Lean 5.7 ± 3.0 Fat 186 ± 69
7.4 ± 1.2 377 ± 76
51.8 ± 14.0 71.2 ± 24.0
9.3 ± 3.3 387 ± 95
<0.1 29 ± 17
8.3 ± 2.2 32 ± 10
6.2 ± 1.1 34 ± 16
Loin steak or medalliond Lean, raw 2.3 Fat, raw 128
5.7 324
51 74
6.8 435
<0.1 20
8.8 26
4.3 17
Filletd Lean, raw
5.5
15.0
5.0
9.0
<0.1
1.0
1.0
Rump steakd Lean, raw Fat, raw
4.9 192
7.9 409
74 116
15 588
<0.1 30
12 55
7.0 41
Round steakd Lean, raw
1.7
4.5
55
9.0
0.4
9.0
5.4
4.9
6.6
71
11
<0.1
11
8.0
Topside steakd Lean, raw Silverside steak Lean, raw
a b c d
d
18.0
8.5
71
9.5
0.2
11
6.4
Diced porkd Raw
11.0
12.2
66
25
0.3
12
8.8
Pork stripsd Raw
5.5
8.1
68
16
<0.1
11
7.5
Pork minced Raw
29
69
78
84
<0.1
18
14
Loin roastd Lean, raw Fat, raw
5.4 187
8.9 360
34 148
17.7 755
<0.1 14
6.8 84
4.6 90
Round (mini) roastd Lean, raw 13.0 Fat, raw 144
3.8 232
31 116
8.9 440
<0.1 1.8
5.5 59
4.1 55
Scotch roastd Lean, raw Fat, raw
32 296
93 41
66 243
<0.1 23
19 18
12 13
20 138
Results are shown as means for duplicate composites from each of three Australian States (6 analytical samples), single determinations. Limit of quantification 0.1 mg/100 g. Results are means ± standard deviation for single composites for each of three Australian States (6 analytical sample), single determinations. Results are for single composites for three Australian States (one analytical sample), single determinations.
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(0.75 ± 0.072 g/kg homogenate) as well as satisfactory test sample duplicates results with differences between duplicates at 1–8% of their mean. For the fatty acids analyses the values obtained for NIST 1546 in g/kg of homogenate were within the acceptable range for the certified values for C10:0, capric acid (0.171 ± 0.032 g/kg), C12:0, lauric acid (0.133 ± 0.028 g/kg), C14:0, myristic acid (2.53 ± 0.19 g/kg), C16:0, palmitic acid (45.6 ± 3.9 g/kg), C18:0, stearic acid (21.7 ± 2.9 g/kg), C18:1, oleic acid (82.0 ± 9.6) and C20:0, arachidic acid (0.315 ± 0.063); and within the acceptable range for the NIST 1546 reference values for C8:0, caprylic acid, C16:1 palmitoleic acid, C18:2n-6, linoleic acid, C18:3n-3, alpha-linolenic acid and C20:4n-6, arachidonic acid. Analytical precision for test duplicates for the lean portion of loin chop and the fat portion of loin chop was mostly in the range 0–4%, with the exception of one saturated fatty acid in fat and lean, C17:0, margaric acid, at 13% and 15%, respectively, and several polyunsaturated fatty acids in lean only, C20:3n-6 at 29%, C20:4n-6 at 8%, C22:4n-6 at 19%, and C22:5n-3 at 15%. 3.2. Variability study of lipid composition of loin chop The analysis of two composites per State for loin chop enabled testing for cholesterol for differences between States, between cooked and raw, and between lean and fat, and the interactions between these factors. For fatty acids, testing was only possible between States and between raw lean and raw fat, as no determinations were carried out on cooked samples. For both cholesterol and fatty acids, the majority of significant differences (p < 0.05) were between lean and fat. There were a small number of significant differences between the States, however these were
not consistent across fatty acids and were not readily interpretable and the magnitude of the differences was generally much less than those for lean vs. fat. Accordingly, means and standard deviations were calculated for cholesterol and fatty acids in raw lean and raw fat, cooked lean and cooked fat, for this cut, across the six composite samples (3 Australian States 2 replicates). The standard deviations must be interpreted with caution as they reflect analysis of six composite samples, not analysis of individual pork chop samples, so do not represent true variation in composition of loin chop across the three States. This compromise was the consequence of forming analytical homogenates over many purchased samples prior to nutrient and fatty acid analysis, due to budget constraints (Greenfield et al., 2008). 3.2.1. Variability study of cholesterol composition of loin chop The cholesterol composition of the 13 pork cuts is shown in Table 1, along with the previously reported data for moisture and total fat composition (Greenfield et al., 2009). The variability study for loin chop showed that cholesterol content was significantly higher (p < 0.001) in separable lean than in separable fat, with this difference being much greater for cooked samples than for raw samples (significant fat/lean raw/cooked interaction; p = 0.002). This is consistent with cholesterol’s structural role in cell membranes and the higher concentration of cell membranes in muscle tissue than adipose tissue. Cholesterol content was higher in cooked lean than raw lean samples, due to the concentration effect of moisture and fat loss in the cooked meat samples. There were no differences in cholesterol content between separable fat samples, raw and cooked. However, the data reflect in part the observed considerable variability in cholesterol analytical method performance as well as any variability across States and replicate
Table 4 Saturated fatty acids (SFA) composition of 12 other pork cuts, raw, per cent total fatty acidsa. Cut
a b
C4:0
C10:0
C12:0
C14:0
C15:0
C16:0
C17:0
C18:0
C20:0
C22:0
C24:0
Total SFA
<0.1 <0.1
<0.1 <0.1
1.1 1.4
0.1 <0.1
23.2 25.8
0.3 0.5
12.2 14.6
<0.1 0.1
0.2 <0.1
0.2 <0.1
37.3 42.5
0.2
0.1
1.5
0.1
24.6
0.4
11.9
<0.1
<0.1
<0.1
38.8
<0.1 <0.1
0.1 <0.1
<0.1 <0.1
1.1 1.3
<0.1 0.1
22.8 23.6
0.4 0.6
11.7 12.0
<0.1 0.1
0.2 <0.1
0.3 <0.1
36.6 37.8
Round steak Lean, raw
0.1
<0.1
<0.1
0.8
0.1
21.2
0.4
11.6
<0.1
0.2
0.4
34.9
Topside steak Lean, raw
<0.1
Loin steak or medallion Lean, raw <0.1b Fat, raw <0.1 Fillet Lean, raw <0.1 Rump steak Lean, raw Fat, raw
0.1
0.1
1.1
<0.1
22.4
0.4
11.0
<0.1
0.2
0.3
35.6
Silverside steak Lean, raw <0.1
<0.1
<0.1
1.1
<0.1
23.5
0.4
12.1
<0.1
0.2
0.3
37.5
Diced pork Raw
<0.1
<0.1
<0.1
1.2
<0.1
22.6
0.4
11.6
<0.1
0.1
0.2
36.0
Pork strips Raw
<0.1
<0.1
<0.1
1.1
<0.1
22.0
0.4
11.6
<0.1
0.1
0.2
35.5
Pork mince Raw
0.5
<0.1
<0.1
1.5
0.1
24.1
0.5
13.0
<0.1
<0.1
<0.1
39.8
Loin roast Lean, raw Fat, raw
<0.1 <0.1
0.1 <0.1
<0.1 <0.1
1.2 1.4
<0.1 0.1
23.4 24.1
0.5 0.7
12.2 13.1
<0.1 0.1
<0.1 <0.1
0.1 <0.1
37.4 39.5
Round (mini) roast Lean, raw <0.1 Fat, raw <0.1
<0.1 <0.1
<0.1 0.1
1.1 1.6
0.1 0.1
21.8 24.0
0.5 0.5
10.9 11.4
<0.1 <0.1
0.1 <0.1
0.3 <0.1
34.8 37.6
Scotch roast Lean, raw Fat, raw
0.1 <0.1
<0.1 <0.1
1.4 1.6
<0.1 <0.1
23.6 26.7
0.4 0.6
13.2 15.3
<0.1 0.1
<0.1 <0.1
<0.1 <0.1
38.7 44.2
<0.1 <0.1
Results are for a single composite for three Australian States (one analytical sample), single determinations. Limit of quantification 0.1%.
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composites. The apparent retention data for cholesterol on dryfrying were 100%, again consistent with cholesterol as an integral component of cell membranes.
3.2.2. Variability study of fatty acids composition of pork loin chop The data for saturated, monounsaturated and polyunsaturated fatty acid composition of loin chop are shown in Table 2 (% total), and Table 3 (specific acids as mg/100 g meat). The predominant saturated fatty acid in loin chop was C16:0, palmitic acid, followed by C18:0, stearic acid, with low amounts of C14:0 and there were slightly higher proportions of these acids in the separable fat than the separable lean (p = 0.01, 0.001, 0.008, respectively; Table 2). Differences between States for lean were only significant for C16:0 (Queensland and Victoria > Western Australia; p = 0.006). For the monounsaturated fatty acids in loin chop, the predominant acid was C18:1, oleic acid, with slightly higher proportions in the separable fat than the separable lean (p = 0.009), followed by C16:1, present in low proportions and slightly higher in lean than in fat (p < 0.001) (Table 2). There were no significant differences between States (p = 0.286, 0.951, respectively). The predominant polyunsaturated fatty acid in loin chop was linoleic acid, C18:2n-6, with higher proportions of this acid in the lean tissue from the Western Australian samples than those from Queensland and Victoria but lower proportions in the fat tissue of the samples from Victoria than those from the other two States (significant fat/lean State interaction; p = 0.037) (Table 2). These lean differences may be due to a higher proportion of lupin in pig feeds in Western Australia than elsewhere. Arachidonic acid, C20:4n-6, was the next most dominant acid with much higher levels in lean tissue than fat tissue, and no significant differences be-
tween the three States (p = 0.517). Alpha-linolenic acid, C18:3n-3, which was present at low levels (below 1% total acids) was significantly higher in the Western Australian samples than those from the other two States (p = 0.021). Other polyunsaturated acids were at low proportions (<1%). Table 3 shows some fatty acids of specific interest in loin chop as mg/100 g food. Amongst the n-3 fatty acids, eicosapentaenoic acid (EPA) was undetectable in the lean tissue of loin chop, whilst alpha-linolenic acid (ALA), docosapentaenoic acid (DPA) and docosahexaenoic acid were at low levels in the lean tissue i.e. between 5 and 13 mg/100 g. In the fat tissue these acids were at low levels from 10–50 mg/100 g apart from ALA which was present in the fat tissue at levels of 280–460 mg/100 g. Both conjugated linoleic acid, c-9, t-11 and C18:1t were present at low levels in the lean tissue of loin chop, at <10 mg/100 g, whilst levels in the fat tissue were >150 mg/100 g. Arachidonic acid, C20:4n-6, was present at levels of 40–100 mg/100 g in both lean and fat.
3.3. Representative study of lipid composition of 12 other pork cuts 3.3.1. Cholesterol content The data for cholesterol content of the 12 other pork cuts studied are shown in Table 1. Cholesterol levels in raw lean tissue ranged from 43 to 69 mg/100 g, whilst levels in raw fat tissue ranged from 38–76 mg/100 g. In general, as for loin chop, on a per cut basis, cholesterol levels were higher in the lean tissue than the fat tissue, probably reflecting the presence of cholesterol in cell membranes. Caution is needed in drawing conclusions from comparisons of raw and cooked cuts since the cuts were from different samples in each case, and only apparent cooking retentions could
Table 5 Monounsaturated fatty acids (MUFA) composition of 12 other pork cuts, raw, per cent total acidsa. C16:1
C17:1
C18:1
C18:1 9t
C20:1
C22:1
C24:1
Total MUFAb
3.4 2.3
0.6 <0.1
39.3 43.0
0.4 0.5
0.6 0.8
<0.1 <0.1
<0.1 0.2
44.3 46.8
3.4
<0.1
45.3
1.0
0.8
<0.1
<0.1
50.5
<0.1 <0.1
2.8 2.4
0.6 <0.1
38.2 45.0
0.4 0.6
0.6 0.8
<0.1 <0.1
<0.1 <0.1
42.6 48.8
Round steak Lean, raw
<0.1
2.4
1.2
34.5
0.4
0.6
<0.1
<0.1
39.1
Topside steak Lean, raw
<0.1
3.2
0.7
38.7
0.3
0.6
<0.1
<0.1
43.5
Silverside steak Lean, raw
<0.1
3.6
0.7
39.9
0.4
0.7
<0.1
<0.1
45.2
Diced pork Raw
<0.1
2.8
0.5
41.1
0.4
0.7
<0.1
<0.1
45.6
Pork strips Raw
<0.1
2.8
0.6
39.2
0.4
0.6
<0.1
<0.1
43.6
Pork mince Raw
0.3
2.8
0.1
42.0
0.7
0.7
<0.1
<0.1
46.6
Loin roast Lean, raw Fat, raw
<0.1 <0.1
2.8 2.4
0.4 <0.1
41.8 41.8
0.4 0.5
0.7 0.8
<0.1 <0.1
<0.1 <0.1
46.0 45.5
Round (mini) roast Lean, raw <0.1 Fat, raw <0.1
2.9 3.0
0.7 <0.1
38.4 43.9
0.4 0.5
0.7 0.8
<0.1 <0.1
<0.1 <0.1
43.0 48.1
Scotch roast Lean, raw Fat, raw
2.7 2.6
0.2 <0.1
42.0 43.1
0.4 0.6
0.7 0.8
<0.1 <0.1
<0.1 0.1
46.0 47.3
Cut
a b c
C14:1
Loin steak or medallion Lean, raw <0.1c Fat, raw <0.1 Fillet Lean, raw <0.1 Rump steak Lean, raw Fat, raw
<0.1 <0.1
Results are for single composites for three Australian States, (one analytical sample), single determinations. Includes C18:1 t1. Limit of quantification 0.1%.
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A.J. Sinclair et al. / Food Chemistry 121 (2010) 672–681
be calculated, not true cooking retentions (Murphy et al., 1975). However, apparent cholesterol retentions in both separable lean and separable fat were 100% during the dry-frying cooking process, but 90% during roasting, when data for all 13 cuts were considered together. 4.3.2. Fatty acids The fatty acids composition of the 12 other pork cuts are shown as percentage total in Table 4 (saturated), Table 5 (monounsaturated), Table 6 (polyunsaturated) and, expressed as mg/100 g meat, in Table 3 (specific fatty acids). Most of these cuts were very similar in composition to loin chop in terms of saturated and monounsaturated fatty acids. However, the overall composition of fatty acids in pork mince, pork strips and diced pork, indicated a mixture of lean and fat tissue, and the measured level of 0.5% for C4:0 in pork mince may have reflected cross-contamination from mincing machines. For the polyunsaturated fatty acids the results were very variable by cut, with higher overall levels of PUFA of a cut reflecting its higher levels of C18:2n-6. The biological significance of these differences cannot be determined from these data, and may simply reflect analytical variability only. 4. Discussion 4.1. Comparison of lipid composition across Australian States There were no differences in cholesterol composition between States, but small differences in fatty acid composition were seen between States, Western Australian lean samples having signifi-
cantly lower levels of C16:0 and significantly higher levels of C18:2n-6, and alpha-linolenic acid, C18:3n-3, possibly due to lupin in Western Australian pig feeds. 4.2. Comparison of lipids in present-day pork with assessments in the 80s and 90s 4.2.1. Cholesterol content In contrast to the data of the 80s (Hutchison et al., 1987) and 90s (Barnes et al., 1996), present-day pork has higher levels of cholesterol in the lean tissue than the fat tissue. Thus levels of cholesterol in lean tissue are similar to those of the 80s and 90s but are lower in the fat tissue at the present time, possibly due to the much higher moisture levels of present-day pork (23.8 g/100 g now vs 11.7 g/100 g in the 80s). It should be mentioned, however, that the cholesterol method used in the 80s was an enzymatic kit method, not GLC as in the present study and the study done in the 90s. 4.2.2. Fatty acid composition In the 80s the then analytical team at the University of New South Wales was commissioned to analyse pork by column chromatography for fatty acids with chain length and unsaturation up to C18:3 only and comparable data for the present study are therefore not available from Hutchison et al. (1987). However, data produced by capillary chromatography are available from Sinclair and O’Dea (1987) for some similar pork cuts. The proportion of DHA in the 1987 sample was lower than in the present study, although the total level of long-chain n-3 fatty acids was similar in both studies.
Table 6 Polyunsaturated fatty acids (PUFA) composition of 12 other pork cuts, raw, per cent total acidsa. Cut
C18:3n3
C20:2n6
C20:3n6
C20:3n3
Loin steak or medallion Lean, raw 12.1 0.1 Fat, raw 9.3 <0.1
0.5 0.6
0.4 0.4
0.5 <0.1
0.1 <0.1
Fillet Lean, raw
a
C18:3n6
C20:4n6
C20:5n3
C22:2n6
C22:4n6
C22:5n3
C22:6n3
Total PUFA
3.4 0.1
<0.1b <0.1
<0.1 <0.1
0.5 <0.1
0.6 <0.1
0.3 <0.1
18.4 10.4
9.1
<0.1
0.9
0.4
0.1
<0.1
0.5
<0.1
<0.1
0.1
0.1
0.1
11.3
Rump steak Lean, raw 14.0 Fat, raw 11.4
0.1 <0.1
0.7 0.8
0.4 0.5
0.5 <0.1
<0.1 0.1
3.4 0.2
<0.1 <0.1
<0.1 <0.1
0.4 <0.1
0.6 <0.1
0.3 <0.1
20.4 13.0
Round steak Lean, raw 17.5
0.2
0.7
0.4
0.6
<0.1
4.6
<0.1
<0.1
0.6
0.8
0.5
25.8
Topside steak Lean, raw 13.9
0.1
0.5
0.4
0.5
<0.1
3.7
<0.1
<0.1
0.4
0.6
0.4
20.6
Silverside steak Lean, raw 10.6
<0.1
0.4
0.4
0.5
<0.1
3.6
<0.1
<0.1
0.5
0.5
0.3
16.8
Diced pork Raw 13.2
<0.1
0.8
0.4
0.3
0.1
2.2
<0.1
<0.1
0.3
0.4
0.3
18.1
Pork strips Raw
b
C18:2n6
14.5
0.1
0.7
0.4
0.4
<0.1
3.1
<0.1
<0.1
0.4
0.5
0.3
20.5
Pork mince Raw 10.7
<0.1
0.8
0.4
0.2
0.1
0.8
<0.1
<0.1
0.2
0.2
0.2
13.6
Loin roast Lean, raw Fat, raw
<0.1 <0.1
0.8 0.9
0.4 0.5
0.3 <0.1
0.1 0.1
1.6 0.2
<0.1 <0.1
<0.1 <0.1
0.3 <0.1
0.3 0.1
0.2 0.1
16.2 14.7
Round (mini) roast Lean, raw 15.5 Fat, raw 11.8
0.1 <0.1
0.8 0.9
0.5 0.5
0.5 <0.1
0.1 0.1
3.1 0.3
<0.1 <0.1
<0.1 <0.1
0.4 0.1
0.6 0.1
0.4 0.1
22.0 13.9
Scotch roast Lean, raw 11.6 Fat, raw 7.3
<0.1 <0.1
0.8 0.4
0.4 0.4
0.2 <0.1
0.1 <0.1
1.2 <0.1
<0.1 <0.1
<0.1 <0.1
0.2 <0.1
0.3 <0.1
0.2 <0.1
14.9 8.1
12.2 12.8
Results are for single composites for three Australian States (one analytical sample), single determinations. Limit of quantification 0.1%.
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A.J. Sinclair et al. / Food Chemistry 121 (2010) 672–681
Table 7 Comparison of Australian pork and Australian red meats for selected fatty acids composition, raw, separable fat and separable lean, mg/100 g.
Red meat 2002 Beef – lean Beef – fat Veal – lean Veal – fat Lamb – lean Lamb – fat Mutton – lean Mutton – fat Pork 2005/6b Lean Fat Lean + fat
C18:1 trans
C20:4n-6
C18:3n-3 (ALA)
C20:5n-3 (EPA)
C22:5n-3 (DPA)
C22:6n-3 (DHA)
C18:2c9t11 (conjugated linoleic acid)
75 2428 22 2957 123 4850 102 2659
70 0 55 0 93 0 97 0
41 385 19 379 64 1444 100 1159
29 0 28 0 27 0 46 0
45 32 32 82 45 204 54 143
6 0 7 0 13 0 19 0
20 663 10 1224 46 1325 31 712
10 333 29
54 94 56
16 475 43
0 20 1
9 46 11
6 42 8
8 162 17
a
a
from Droulez et al. (2006). Concentrations are means over cuts with separable lean and fat components. Lean + fat are overall concentrations, obtained by weighting the concentrations in lean and fat in each component by the relative gross composition of lean and fat from Müller et al. (2009). b
Comparison of the fatty acids data from the present study with those from the study carried out in the 90s, which used pooled samples from several cuts (Barnes et al., 1996), is not possible because the text does not specify whether these pooled samples were fat, lean, or a mixture of both tissues. 4.3. Comparison of fatty acid composition of present-day pork with present-day red meats Nutrient profiling of animal products is an important strategy in their marketing in Australia. Table 7 therefore displays a comparison of the fatty acids composition of current pork and red meats (Droulez, Williams, Levy, Stobaus, & Sinclair, 2006). As expected, meat from pork, as a non-ruminant animal, had much lower levels of trans-acids than red meats from ruminant animals. Pork lean tissue compares unfavourably with lean tissue in red meats with respect to content of EPA, DPA, ALA and CLA. However, DHA levels of lean pork are only slightly lower than those of lean red meats. The Australian pigmeat industry has recently published the results of fishmeal feeding trials which significantly increased the EPA and DHA by fourfold or more with organoleptic profiles and stability comparable with those of regular pork (Sioutis et al., 2008). 4.4. Comparisons with pork data from other countries 4.4.1. Cholesterol content Comparisons with UK data (Food Standards Agency, 2008), Danish data (National Food Institute, 2008) and USDA data (Howe, Trainer, & Holden, 2007) show that the cholesterol data in the present study are in contrast since the cholesterol content of separable lean was higher than in separable fat. The reasons are unclear but may be due to method performance in this study, or to real differences in rearing and feeding of pigs in these other countries. 4.4.2. Fatty acid composition Comparisons with data for UK pork (Food Standards Agency, 2008) reveal that Australian pork would appear to be lower in levels of EPA, DPA and DHA since the UK food tables give levels of 0.01 g/100 g, 0.02 g/100 g and 0.01 g/100 g, respectively, for these acids in pork, trimmed lean, raw, probably reflecting feeding differences. Comparisons with US fresh pork, lean only, raw cannot be made as the latest release of USDA food composition data, SR 22, does not show values for these acids in these cuts (USDA, 2009). This observation also applies to the most up-to-date version of the Danish food composition tables (National Food Institute, Technical University of Denmark, 2008).
5. Conclusions This comprehensive study of national and cut variation of cholesterol and fatty acids in Australian pork appears to be the first such study published for this product and the data will contribute to the Australian food composition tables that are heavily used in dietary and food regulatory work. Cholesterol levels in separable lean were similar to those seen in more limited studies undertaken in previous decades, whilst cholesterol in separable fat had declined over the period. For fatty acids the study showed some variability in the polyunsaturated fatty acids composition by State which may have been due to feeding differences. However, the results may have been confounded by analytical variability and differences in the carcase location and configuration of cuts. Levels of DHA in separable lean were not as low as previously thought, but the levels of long-chain n-3 acids in pork are considerably lower than in Australian lean red meats. Industry efforts to improve the levels of these acids in pork appear justified especially given the high level of interest in improving the dietary intakes of these acids in Australia. Acknowledgments We wish to thank Janet Stark, Sharon Kennedy, Keith Pitts and Steve Humphries of FSA for technical assistance, dissection and processing of meat samples and Mendi Sulentic for data entry and data verification. Darryl D’Souza and Tami Macadam of APL provided additional advice. This study was funded by Australian Pork Limited. References AOAC International. (2005/2006). Official Methods of Analysis (OMA) (18th ed./ Revision 1). Arlington, VA: AOAC International. www.eoma.aoac.org; Accessed 10.07.07. Badings, H. T., & De Jong, C. (1983). Glass capillary gas chromatography of fatty acid methyl esters. A study of conditions for the quantitative analysis of short- and long-chain fatty acids in lipids. Journal of Chromatography, 279, 493–506. Barnes, J. A., Lewis, J. L., & Buick, D. R. (1996). Composition of new-fashioned pork 1994. Food Australia, 48(Suppl.), 1–15. Bligh, E. G., & Dyer, W. J. (1959). A rapid method for total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology, 3, 911–917. Christie, W. W. (1993). Preparation of ester derivatives of fatty acids for chromatographic analysis. In W. W. Christie (Ed.), Advances in lipid methodology (pp. 69–111). Dundee: Oily Press. Cobiac, L., Droulez, V., Leppard, P., & Lewis, J. (2003). Use of external fat width to describe beef and lamb cuts in food composition tables. Journal of Food Composition and Analysis, 16, 133–145. Department of Agriculture, Fisheries and Forestry. (2007).; Accessed 30.06.08.
A.J. Sinclair et al. / Food Chemistry 121 (2010) 672–681 Droulez, V., Williams, P., Levy, G., Stobaus, T., & Sinclair, A. J. (2006). Composition of Australian red meat 2002: 2. Fatty acid profile. Food Australia, 58, 335–341. Food and Agriculture Organization. (2009). Background to INFOODS.. Food Standards Agency. (2008). McCance and Widdowson’s Composition of Foods integrated dataset (CoF IDS). Accessed 30.06.08. GenStat for Windows. (2007). (9th ed.). Hemel Hempstead, U.K.: VSN International Ltd. Greenfield, H., & Southgate, D. A. T. (2003). Food composition data. Production, management and use. Rome: FAO. . Greenfield, H., Arcot, J., Barnes, J. A., Cunningham, J., Adorno, P., Stobaus, T., et al. (2009). Nutrient composition of Australian retail pork cuts 2005/2006. Food Chemistry, 117, 721–730. Greenfield, H., Barnes, J. A., Tume, R. K., Beilken, S., Stobaus, T., Bruce, H. L., et al. (2008). Surely for doing a nutrient analysis of meat, all you have to do is mince it all up and analyse it? A national study of the nutrient composition of Australian pork. Food Australia, 60, 30–33. Hermesch, S. (2006). Outline of R&D directions for Australian pig genetics. Animal Genetics & Breeding Unit, University of New England. ; Accessed 02.07.08.
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Howe, J. C., Trainer, D., & Holden, J. M. (2007). USDA nutrient data set for fresh pork (derived from SR), release 1.1*.; Accessed 30.09.07. Hutchison, G. I., Greenfield, H., & Wills, R. B. H. (1987). Composition of Australian foods: 35. Pork.. Food Technology in Australia, 39, 216–222. Müller, W. J., Bruce, H. L., Tume, R. K., Beilken, S. L., Barnes, J. A., & Greenfield, H. (2009). National sampling and gross composition of Australian retail pork cuts 2005/2006. Meat Science, 81, 626–631. Murphy, E. W., Criner, P. E., & Gray, B. C. (1975). Comparisons of methods for calculating retentions of nutrients in cooked foods. Journal of Agricultural and Food Chemistry, 23, 1153–1157. National Food Institute, Technical University of Denmark. (2008). Danish food composition databank, rev. 7.00. ; Accessed 14.12.08. Sinclair, A. J., & O’Dea, K. (1987). The lipid levels and fatty acid compositions of the lean portions of pork, chicken and rabbit meats. Food Technology in Australia, 39. pp. 232–233, 240. Sioutis, S., Coates, A. M., Buckley, J. D., Murphy, T. W., Channon, H. A., & Howe, P. R. C. (2008). N-3 enrichment of pork with fishmeal: Effects on production and consumer acceptability. European Journal of Lipid Science and Technology, 110, 701–706. USDA, US Department of Agriculture, Agricultural Research Service. (2009). USDA national nutrient database for standard reference, release 22. ; Accessed 18.10.09.
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Food Chemistry journal homepage: www.elsevier.com/locate/foodchem
Lipid composition of Australian pork cuts 2005/2006 Andrew J. Sinclair a, Sebastian Barone b, Tim Stobaus b, Ron Tume c, Shane Beilken c, Warren Müller d, Judy Cunningham e, Jane A. Barnes f, Heather Greenfield g,h,* a
School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood VIC 3125, Australia National Measurement Institute, 1/153 Bertie Street, Port Melbourne, VIC 3207, Australia c Food Science Australia, P.O. Box 3312, Tingalpa DC QLD 4173, Australia d CSIRO Mathematical and Information Sciences, G.P.O. Box 664, Canberra ACT 2601, Australia e Food Standards Australia New Zealand, P.O. Box 7186, Canberra BC ACT 2610, Australia f Foodsense, P.O. Box 551, Mosman NSW 2088, Australia g Faculty of Veterinary Science, University of Sydney, NSW 2006, Australia h Food Science and Technology, School of Chemical Sciences and Engineering, University of New South Wales, Sydney, NSW 2052, Australia b
a r t i c l e
i n f o
Article history: Received 3 July 2009 Received in revised form 19 October 2009 Accepted 24 December 2009
Keywords: Pork Fatty acids Cholesterol Australia
a b s t r a c t A study of the cholesterol content and fatty acid composition of fresh retail Australian pork was undertaken to determine whether new breeding, feeding and processing methods had resulted in any compositional changes in fresh pork in the market place since surveys undertaken in previous decades. Samples of 13 popular pork cuts were purchased from randomly selected supermarkets and butchers’ stores in urban areas across the socioeconomic scale in three States of Australia, and analysed, separable fat and separable lean, in late 2005 and early 2006. Variability was low across States for saturated and monounsaturated fatty acids, but more pronounced for polyunsaturated acids. The separable lean portions of all pork cuts contained levels of n-3 fatty acids and conjugated linoleic acid (C18:1c9t11) in measurable but not nutritionally claimable amounts, whilst total trans fatty acid levels were very low. There appeared to be some differences in fatty acid composition across States that may have resulted from feeding method. Cholesterol contents were similar to levels in the 80s and 90s for separable lean pork tissue, but presently are lower for separable fat tissue than for separable lean. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction The Australian pork industry contributed $2.9 billion Australian dollars to the national economy in 2006–07. About 15–20% of pigmeat production is exported annually, to markets in Asia and Australasia, with the figure for 2006–07 at 39,100 tonnes (Department of Agriculture & Forestry, 2007). Analytical data for the nutrient composition of Australian fresh pork as available for purchase by consumers were published for 1983–84 using samples of six cuts collected from retail outlets in Sydney suburbs across the socioeconomic scale (Hutchison, Greenfield, & Wills, 1987) and subsequently updated a decade later in 1994 with analysis of samples, this time of 13 cuts, again gathered from retail outlets in Sydney suburbs (Barnes, Lewis, & Buick, 1996). In both of these studies the lipid analyses were performed only on a single composite sample for each cut. In the 2000s the move has been to purchase com-
* Corresponding author. Address: Food Science and Technology, School of Chemical Sciences and Engineering, University of New South Wales, Sydney, NSW 2052, Australia. Tel.: +61 293987695. E-mail address: heather.greenfi[email protected] (H. Greenfield). 0308-8146/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2009.12.096
modities for nutritional analysis more widely across Australia, as exemplified by a study of Australian red meats (Cobiac, Droulez, Leppard, & Lewis, 2003). Further, due to greater awareness of the nutritional significance of long-chain n-3 fatty acids, conjugated linoleic acid and trans-fatty acids to consumers, there was a need to carry out more detailed analyses of these lipid components in fresh retail pork using capillary gas chromatography. Therefore Australian Pork Limited (APL) commissioned a national study of fresh retail pork as available to Australian consumers in the early 21st century. This study was to provide gross compositional and comprehensive nutrient data that would reflect the product as nationally available, for product nutrition labelling, for promotional purposes and for provision of data to the ongoing national food composition database (NUTTAB) compiled by (Food Standards Australia New Zealand, 2007) and used for national public health nutrition, dietetic and food regulation purposes. A new study was additionally necessary as there had been considerable changes in rearing, feeding and genetics of pigs over the previous decade, with more uniformity of these factors nationwide and the production of larger, leaner pigs (Hermesch, 2006). The establishment of INFOODS in 1984 (FAO, 2009), recognised the importance of the production and sharing of good quality food composition data
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internationally, particularly for public health nutrition and trade purposes. Accordingly INFOODS introduced internationally agreed guidelines for methods for producing, expressing and sharing such data in compatible formats. The specific objectives of the present study were: to examine the variation in content of these lipid components from pork samples from different parts of the country; to determine if there had been any changes in pork cholesterol and fatty acid composition in the last decade compared with previous assessments; to compare the lipid composition of pork with recent data for Australian red meats; to compare the fresh Australian pork product with that of other industrialised countries; and, to provide pork lipid compositional data for inclusion in current Australian food composition tables (NUTTAB) maintained by FSANZ.
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one of the samples (selected at random) was dissected and measured for gross composition. Samples were held at 1–2°C before and during handling, and kept covered in closed polyethylene bags to minimise evaporation of moisture. As soon as dissection had been completed, samples were re-bagged and returned to a cold room at 1–2°C. All cuts were photographed on arrival and during laboratory handling. 2.3. Cooking methods All cuts were analysed for cholesterol as separable lean and separable fat, in the raw state and in the cooked state. Cooking methods were as specified by APL home economists to reflect household practice then adapted for the available equipment. Details of cooking methods are given in Müller et al. (2009).
2. Materials and methods 2.4. Preparation of analytical homogenates 2.1. General approach The general approach to this overall study has been described elsewhere (Greenfield et al., 2008). 2.2. Sampling, pork cuts and collection procedures The national sampling scheme, nomination of cuts, and cut collection procedures are described in detail by Müller et al. (2009) along with results for gross composition analyses. The overall sampling scheme for each pork cut was:
3 States 3 SEC 2 replicate suburbs 2 retailer types 2 conditions ðraw; cookedÞ ¼ 72 samples ðpurchasesÞ where, State = Australian State; retailer type = butcher/supermarket; SEC = socioeconomic status of suburb (high, medium, low). The 13 cuts which were advised to be the more popular consumer cuts and therefore selected were: loin chop, loin steak, fillet, rump steak, round steak, topside steak, silverside steak, diced pork, pork strips, pork mince, loin roast, round (mini) roast, scotch (neck) roast. One cut, the loin chop, was studied in more detail across all three States, in order to provide additional data on compositional variability. Sample collection and handling generally followed international guidelines issued by Food and Agriculture Organisation/International Network of Food Data Systems (Greenfield & Southgate, 2003). Pork loin chop samples were collected in December 2005, and the other cuts progressively from February to May 2006. For the 13 cuts the number of actual purchases was 911 instead of the planned 936 because of a small number of cuts that were unavailable on the day of collection. Sample collection was organised by APL representatives in each of the three States and shoppers were commissioned to purchase duplicate samples (e.g. two pork roasts or 2 kg of smaller cuts) anonymously from each nominated retail outlet. Shoppers were instructed not to specify whether trimmed or untrimmed cuts were desired. The meat samples were packed and freighted chilled to the Food Science Australia (FSA) laboratory in Queensland by air from Melbourne, Victoria and Perth, Western Australia and by road from Brisbane. Meat temperatures were checked on arrival at FSA and all samples were stored at 1–2 °C until required for processing, either immediately or later on the same day. Where incorrect cuts had been supplied attempts were made to obtain replacements, or were later designated as missing values along with those that were not available. The duplicate samples purchased for each cut were randomly allocated to either raw or cooked treatment. For purchases consisting of several samples (e.g. loin chop) only
For each cut except loin chops, four analytical homogenates were formed from the individual purchases, cooked and raw, fat and lean, as homogenised composites. For loin chops, 24 analytical homogenates were formed; 3 States 2 replicates 4 portions (lean/fat raw/cooked). The two replicates were obtained by combining the two retailer types from one randomly selected set of a high, a medium and a low SEC area as one composite, and the remaining high, medium and low SEC areas as a second composite. The dissected meat was weighed and aliquot samples were allocated for aggregation according to the experimental design for the particular cut. The aggregate meat sample was coarsely cut, hand mixed and minced through a meat mincer (IRCEM Srl Tritacarne Type I-E 22, 240V, Italy) using a single blade and a 4 mm mincing plate. The samples were then recombined and minced again to attain adequate homogeneity. Contact with metal was minimised wherever possible. The mincer was dismantled and washed after each sample was minced to eliminate cross-contamination between samples. Temperatures were maintained at 1–2 °C throughout preparation of analytical homogenates. Initially, a number of individual samples were assessed by measuring homogeneity by the reproducibility of their moisture contents to establish the degree of mixing required. Samples within a 2% moisture range were assessed as sufficiently homogenised e.g. 75% + 2%. The samples were then packed in plastic jars and stored chilled or frozen until required for further evaluation. The four (4) composite samples that were obtained for each of the cuts were raw lean, cooked lean, raw fat and cooked fat. For some cuts, only raw lean and cooked lean data were required due to the absence of separable fat on cuts such as fillets. 2.5. Transport of analytical homogenates Samples were coded and sent frozen for the analyses of moisture, fat, cholesterol and fatty acids to National Measurement Institute (NMI) in Melbourne. All samples were freighted in insulated containers by overnight courier on the day following preparation. Samples were vacuum-packed and stored at NMI in a 80 °C freezer. 2.6. Variability study of lipid composition of pork loin chop All 24 composites of loin chop were analysed, separable lean and separable fat, for cholesterol (raw and cooked) and fatty acids (raw only). The cut collection and gross composition work was carried out in December 2005. The analytical work was completed in October 2006.
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2.7. Representative study of lipid composition of 12 other pork cuts 2.7.1. Cholesterol The remaining 12 cuts were analysed as 34 national composites (for 5 cuts: national duplicates 4 portions (lean/fat, raw/cooked), total = 20; for 7 cuts: national duplicates 2 portions (lean only or lean + fat mixed, raw/cooked), total = 14). 2.7.2. Fatty acids The remaining 12 cuts were analysed as 17 national composites (for 5 cuts: 1 national composite 2 portions, lean/fat, raw only, total = 10; for 7 cuts: 1 national composite 1 portion, lean only or lean + fat mixed, raw only, total = 7). The cut collection and gross composition work was done from February to May 2006. The nutrient analytical work was completed in October 2006.
acid present was determined by normalisation of the peak areas obtained. i.e. peak area (individual acid) divided by the sum of peak areas and multiplied by 100 to give the percentage proportion of the acid. For specified fatty acids, e.g. C18:3n-3, this percentage proportion was then multiplied by the total fat present in the sample, as determined by Soxhlet fat extraction, to give a mass/mass value (mg/100 g) of the individual fatty acid in the sample.
Table 1 Moisture, fat and cholesterol composition for 13 pork cuts, separable lean and separable fat, raw and cooked, per 100 g. Fat (g)a
Cholesterol (mg)
74.1 ± 0.7 63.3 ± 0.5 23.8 ± 4.9 21.3 ± 2.4
1.75 ± 0.21 4.47 ± 0.38 69.2 ± 4.6 70.7 ± 3.1
48 ± 17 67 ± 16 39 ± 10 41 ± 10
Loin steak or medallionc Lean, raw 75.5 Lean, cooked 67.7 Fat, raw 26.4 Fat, cooked 30.8
1.6 3.5 68.5 55.5
48 63 38 46
Fillet c Lean, raw Lean, cooked
75.2 68.9
1.1 2.2
47 56
Rump steakc Lean, raw Lean, cooked Fat, raw Fat, cooked
73.7 68.3 27.1 34.9
2.1 3.8 66.4 53.7
45 57 38 32
Round steakc Lean, raw Lean, cooked
75.6 69.3
1.1 1.7
46 62
Topside steakc Lean, raw Lean, cooked
75.1 69.3
2.0 2.3
43 52
Silverside steakc Lean, raw Lean, cooked
75.4 68.8
2.0 3.0
60 63
Diced porkc Raw Cooked
75.2 65.7
3.1 3.1
69 82
Pork stripsc Raw Cooked
75.4 66.4
2.3 2.5
50 59
Pork mincec Raw Cooked
70.6 64.8
9.4 10.2
54 57
Loin roastc Lean, raw Lean, cooked Fat, raw Fat, cooked
74.3 61.4 19.3 26.1
2.2 8.6 77.1 67.0
46 57 38 33
Round (mini) roastc Lean, raw Lean, cooked Fat, raw Fat, cooked
75.5 64.5 45.3 41.4
1.1 2.5 44.6 45.5
68 89 76 65
Scotch roastc Lean, raw Lean, cooked Fat, raw Fat, cooked
72.6 58.9 38.1 39.8
7.6 12.0 52.5 50.5
50 74 48 46
b
Loin chop Lean, raw Lean, cooked Fat, raw Fat, cooked
2.8. Methods of analysis Methods of analysis were agreed in terms of availability and appropriateness for pork, and in terms of the expected ranges of nutrient levels in this commodity. Methods for moisture and fat, previously determined on these samples, appear in the reference to the earlier publication from this study for macro- and micronutrients (Greenfield et al., 2009). 2.8.1. Cholesterol The method used was AOAC gas chromatographic method No. 976.26 (AOAC International. 2005/2006), using a 12 m BP1 capillary column and determination by flame ionisation detector. Limit of quantification was 0.1 mg/100 g. Analyses were performed in duplicate. 2.8.2. Fatty acids Fat was extracted from meat samples (approximately 10 g) using a chloroform: methanol (2:1) extraction process (Bligh & Dyer, 1959). The extracted fat was then transesterified using methanolic sodium methoxide solution, subsequently treated with sulphuric acid in methanol to esterify the free acids (Badings & De Jong, 1983; Christie, 1993) and then re-extracted with hexane. These extracts were analysed for fatty acids using an Agilent 6890 gas chromatograph with flame ionisation detector (Agilent Technologies Australia Pty Ltd., Forest Hill Victoria 3131). Separation of the methyl esters of C4:0 to C24:3 was effected by means of a 100 m polysiloxane bis-cyanopropyl capillary column (Supelco SP™-2560, L I.D. 100 m 0.25 mm, df 0.20 lm) at an initial oven temperature of 90 °C for 1.0 min, then ramped at a rate of 30 °C/min up to 135 °C, then ramped up to a final temperature of 240 °C at 2.5 °C/min, then held for 5.5 min. Total run time was 50 min. The carrier gas was hydrogen set at 1.2 mL per minute at a pressure of 149 kPa in constant flow mode. Identification, integration and calculation of the individual fatty acid concentrations were performed using Agilent Chemstation software against known standards. Results for the individual fatty acids were expressed as a relative percentage of the total fatty acid content (limit of quantification, 0.1%) or, in the case of specific acids, mg/100 g food (limit of quantification, 1 mg/100 g. Samples were analysed as raw only, with single determinations. Each analytical batch was required to conform to a range of quality criteria, including; satisfactory recoveries for in-house control materials and at least one duplicate analysis with results within 10% of the duplicate mean. Also included was a satisfactory determination of the referenced fatty acids for NIST CRM 1546 (meat homogenate), this was performed quantitatively as mg/100 g of the NIST material. The individual fatty acids were determined as a proportion of the total fatty acids present. The proportion of each fatty
Moisture (g)a
Cut
a
Data from Greenfield et al. (2009). Results are means ± standard deviation for two composites from each of three Australian States (6 analytical samples), duplicate determinations. c Results are means for two composites from three Australian States (2 analytical samples), duplicate determinations. b
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2.9. Apparent retention of nutrients
2.11. Data scrutiny
Apparent nutrient retention (%) was calculated as: nutrient content per g of cooked food (dry basis)/nutrient content per g of raw food (dry basis) 100 (Murphy, Criner, & Gray, 1975).
All authors scrutinised the analytical data on receipt. Further scrutiny, including integrity checks, of the complete data sets was performed by three of the authors, Barnes, Cunningham and Greenfield. All scrutineers compiled their own independent lists of queries. After agreement between the scrutineers reached by teleconference, a consolidated list of queries and, in some cases, requests for reanalyses was sent to NMI, Melbourne. Further scrutiny was done, including of repeated analytical results, until all scrutineers were satisfied with the reliability of the analytical data.
2.10. Quality control Cholesterol analyses were performed in duplicate whilst fatty acid analyses were single determinations after preliminary results for loin chop showed mostly only 0–4% differences between duplicate determinations. Quality control procedures for all analyses included the use of National Institute of Standards and Technology (NIST) Standard Reference Material 1546 Meat Homogenate, in-house reference materials (e.g. butter fat, cod liver oil and canola oil for the fatty acid determinations), precision of replicates, recoveries of standards, use of blanks and other routine quality control checks, as appropriate.
2.12. Statistical analyses For each loin chop variable a three-way analysis of variance was performed; 3 States 2 types (lean/fat) 2 cooking categories (cooked/raw). A split plot-type analysis was performed as each of the six States replicates was regarded as a main plot and was split for the four types cooking categories. Variation be-
Table 2 Saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) acid composition of pork loin chop, raw, per cent total fatty acidsa. State/SFA
C14:0
C16:0
C17:0
C18:0
C20:0
C22:0
Total SFA
QLD Lean, raw Fat, raw
1.35 1.40
25.2 24.7
0.40 0.60
12.4 13.3
<0.1b 0.10
0.10 <0.1
39.4 40.2
VIC Lean, raw Fat, raw
1.10 1.45
24.1 26.7
0.30 0.45
12.6 15.2
<0.1 0.20
0.15 <0.1
38.4 44.0
WA Lean, raw Fat, raw
1.15 1.30
22.7 24.7
0.45 0.65
12.0 13.3
<0.1 0.10
0.10 <0.1
36.4 40.1
National mean ± SDc Lean, raw Fat, raw State/MUFA
1.20 ± 0.13 1.38 ± 0.12 C16:1
24.0 ± 1.2 25.4 ± 1.1 C17:1
0.38 ± 0.10 0.57 ± 0.16 C18:1
12.3 ± 0.4 13.9 ± 1.0 C18:1,9t
<0.1 0.13 ± 0.05 C20:1
0.12 ± 0.03 <0.1 C24:1
38.1 ± 1.4 41.4 ± 2.0 Total MUFA
QLD Lean, raw Fat, raw
3.50 2.45
0.45 <0.1
40.6 44.3
0.45 0.50
0.70 0.85
<0.1 <0.1
45.8 48.1
VIC Lean, raw Fat, raw
3.20 2.60
0.60 <0.1
41.4 44.2
0.35 0.55
0.65 0.90
<0.1 <0.1
46.2 48.2
WA Lean, raw Fat, raw
2.65 2.20
0.60 <0.1
40.0 45.6
0.40 0.60
0.70 0.95
<0.1 0.2
44.2 49.6
National mean ± SDc Lean, raw Fat, raw
3.12 ± 0.46 2.42 ± 0.28
0.55 ± 0.10 <0.1
40.7 ± 1.6 44.7 ± 0.8
0.40 ± 0.06 0.55 ± 0.14
0.68 ± 0.04 0.90 ± 0.06
<0.1 <0.1
45.4 ± 1.9 48.6 ± 1.0
State/PUFA
C18:2n-6
C18: 3n-3
C20:2n-6
C20:3n-6
C20:3n-3
C20:4n-6
C20:5n-3
C22:4n-6
Total PUFA
QLD Lean, raw Fat, raw
9.6 10.3
0.40 0.60
0.30 0.45
0.40 <0.1
<0.1 <0.1
2.70 0.15
0.20 <0.1
0.40 <0.1
14.7 11.4
VIC Lean, raw Fat, raw
9.5 6.9
0.35 0.40
0.30 0.40
0.45 <0.1
<0.1 <0.1
3.15 <0.1
0.25 <0.1
0.45 <0.1
15.3 7.7
WA Lean, raw Fat, raw
13.2 9.0
0.75 0.60
0.45 0.55
0.35 <0.1
0.1 <0.1
2.65 <0.1
0.20 <0.1
0.35 <0.1
18.7 10.2
0.50 ± 0.20 0.53 ± 0.12
0.35 ± 0.08 0.47 ± 0.08
0.40 ± 0.06 <0.1
<0.1 <0.1
2.83 ± 0.41 <0.1
0.22 ± 0.04 <0.1
0.40 ± 0.06 <0.1
16.2 ± 2.5 9.7 ± 1.7
National mean ± SDc Lean, raw 10.8 ± 2.1 Fat, raw 8.7 ± 1.6
QLD, Queensland; VIC, Victoria; WA, Western Australia. a Results are shown as means for duplicate composites for each of three Australian States (6 analytical samples), single determinations. b Limit of quantification 0.1%. c National means ± standard deviation (6 analytical samples).
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tween duplicate readings (cholesterol only) was obtained as a final split within the analysis, which enabled the reliability of the analytical method to be assessed. For some fatty acids measurements on lean and fat samples for each cut were analysed separately, as the values for lean and fat were distinctly different and it was inappropriate to use the single analysis. A number of fatty acids had contents below the limit of quantification in all or some of the samples, so no statistical analysis could be performed in those cases. In all cases the key assumptions of analysis of variance, namely homogeneity of variation across the range of values and normally distributed error terms, were checked and found to hold, so no variables required transformation before analysis. The package GenStat for Windows (2007) was used for these analyses. As composites for all the other cuts were formed over all replicate samples, no estimates of variability could be obtained and results are expressed as means over duplicate deter-
minations for cholesterol or as the value from the single determination for fatty acids. 3. Results 3.1. Quality control results for cholesterol and fatty acid analyses The variance ratio for the cholesterol analyses was 1.32 (p = 0.278), meaning that variation between analytical duplicates was similar to variation between test pork composite samples. This reflected poor precision for the performance of the analytical method. Spike recoveries of pure standard which averaged 90% were also somewhat unsatisfactory. However, the laboratory quality control report for the reference material (NIST 1546, Meat Homogenate) showed satisfactory recoveries at a mean of 0.745 g/kg homogenate of the certified content of cholesterol
Table 3 Specific fatty acid composition of pork cuts, separable lean and separable fat, raw, mg/100 g. Cut
C18:2c9t11 (conjugated linoleic acid)
C18:1t9
C20:4n-6
C18:3n-3 (ALA)
C20:5n-3 (EPA)
C22:5n-3 (DPA)
C22:6n-3 (DHA)
Loin chopa QLD Lean Fat
9.4 154
7.5 357
48.1 95.6
7.4 421
<0.1b 32
7.2 43
6.5 51
VIC Lean Fat
3.6 220
6.6 331
61.8 54.7
7.2 282
<0.1 10
9.8 23
6.7 25
WA Lean Fat
4.2 183
8.0 444
45.6 63.2
13.2 459
<0.1 45
7.9 30
5.5 25
National mean ± SDc Lean 5.7 ± 3.0 Fat 186 ± 69
7.4 ± 1.2 377 ± 76
51.8 ± 14.0 71.2 ± 24.0
9.3 ± 3.3 387 ± 95
<0.1 29 ± 17
8.3 ± 2.2 32 ± 10
6.2 ± 1.1 34 ± 16
Loin steak or medalliond Lean, raw 2.3 Fat, raw 128
5.7 324
51 74
6.8 435
<0.1 20
8.8 26
4.3 17
Filletd Lean, raw
5.5
15.0
5.0
9.0
<0.1
1.0
1.0
Rump steakd Lean, raw Fat, raw
4.9 192
7.9 409
74 116
15 588
<0.1 30
12 55
7.0 41
Round steakd Lean, raw
1.7
4.5
55
9.0
0.4
9.0
5.4
4.9
6.6
71
11
<0.1
11
8.0
Topside steakd Lean, raw Silverside steak Lean, raw
a b c d
d
18.0
8.5
71
9.5
0.2
11
6.4
Diced porkd Raw
11.0
12.2
66
25
0.3
12
8.8
Pork stripsd Raw
5.5
8.1
68
16
<0.1
11
7.5
Pork minced Raw
29
69
78
84
<0.1
18
14
Loin roastd Lean, raw Fat, raw
5.4 187
8.9 360
34 148
17.7 755
<0.1 14
6.8 84
4.6 90
Round (mini) roastd Lean, raw 13.0 Fat, raw 144
3.8 232
31 116
8.9 440
<0.1 1.8
5.5 59
4.1 55
Scotch roastd Lean, raw Fat, raw
32 296
93 41
66 243
<0.1 23
19 18
12 13
20 138
Results are shown as means for duplicate composites from each of three Australian States (6 analytical samples), single determinations. Limit of quantification 0.1 mg/100 g. Results are means ± standard deviation for single composites for each of three Australian States (6 analytical sample), single determinations. Results are for single composites for three Australian States (one analytical sample), single determinations.
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(0.75 ± 0.072 g/kg homogenate) as well as satisfactory test sample duplicates results with differences between duplicates at 1–8% of their mean. For the fatty acids analyses the values obtained for NIST 1546 in g/kg of homogenate were within the acceptable range for the certified values for C10:0, capric acid (0.171 ± 0.032 g/kg), C12:0, lauric acid (0.133 ± 0.028 g/kg), C14:0, myristic acid (2.53 ± 0.19 g/kg), C16:0, palmitic acid (45.6 ± 3.9 g/kg), C18:0, stearic acid (21.7 ± 2.9 g/kg), C18:1, oleic acid (82.0 ± 9.6) and C20:0, arachidic acid (0.315 ± 0.063); and within the acceptable range for the NIST 1546 reference values for C8:0, caprylic acid, C16:1 palmitoleic acid, C18:2n-6, linoleic acid, C18:3n-3, alpha-linolenic acid and C20:4n-6, arachidonic acid. Analytical precision for test duplicates for the lean portion of loin chop and the fat portion of loin chop was mostly in the range 0–4%, with the exception of one saturated fatty acid in fat and lean, C17:0, margaric acid, at 13% and 15%, respectively, and several polyunsaturated fatty acids in lean only, C20:3n-6 at 29%, C20:4n-6 at 8%, C22:4n-6 at 19%, and C22:5n-3 at 15%. 3.2. Variability study of lipid composition of loin chop The analysis of two composites per State for loin chop enabled testing for cholesterol for differences between States, between cooked and raw, and between lean and fat, and the interactions between these factors. For fatty acids, testing was only possible between States and between raw lean and raw fat, as no determinations were carried out on cooked samples. For both cholesterol and fatty acids, the majority of significant differences (p < 0.05) were between lean and fat. There were a small number of significant differences between the States, however these were
not consistent across fatty acids and were not readily interpretable and the magnitude of the differences was generally much less than those for lean vs. fat. Accordingly, means and standard deviations were calculated for cholesterol and fatty acids in raw lean and raw fat, cooked lean and cooked fat, for this cut, across the six composite samples (3 Australian States 2 replicates). The standard deviations must be interpreted with caution as they reflect analysis of six composite samples, not analysis of individual pork chop samples, so do not represent true variation in composition of loin chop across the three States. This compromise was the consequence of forming analytical homogenates over many purchased samples prior to nutrient and fatty acid analysis, due to budget constraints (Greenfield et al., 2008). 3.2.1. Variability study of cholesterol composition of loin chop The cholesterol composition of the 13 pork cuts is shown in Table 1, along with the previously reported data for moisture and total fat composition (Greenfield et al., 2009). The variability study for loin chop showed that cholesterol content was significantly higher (p < 0.001) in separable lean than in separable fat, with this difference being much greater for cooked samples than for raw samples (significant fat/lean raw/cooked interaction; p = 0.002). This is consistent with cholesterol’s structural role in cell membranes and the higher concentration of cell membranes in muscle tissue than adipose tissue. Cholesterol content was higher in cooked lean than raw lean samples, due to the concentration effect of moisture and fat loss in the cooked meat samples. There were no differences in cholesterol content between separable fat samples, raw and cooked. However, the data reflect in part the observed considerable variability in cholesterol analytical method performance as well as any variability across States and replicate
Table 4 Saturated fatty acids (SFA) composition of 12 other pork cuts, raw, per cent total fatty acidsa. Cut
a b
C4:0
C10:0
C12:0
C14:0
C15:0
C16:0
C17:0
C18:0
C20:0
C22:0
C24:0
Total SFA
<0.1 <0.1
<0.1 <0.1
1.1 1.4
0.1 <0.1
23.2 25.8
0.3 0.5
12.2 14.6
<0.1 0.1
0.2 <0.1
0.2 <0.1
37.3 42.5
0.2
0.1
1.5
0.1
24.6
0.4
11.9
<0.1
<0.1
<0.1
38.8
<0.1 <0.1
0.1 <0.1
<0.1 <0.1
1.1 1.3
<0.1 0.1
22.8 23.6
0.4 0.6
11.7 12.0
<0.1 0.1
0.2 <0.1
0.3 <0.1
36.6 37.8
Round steak Lean, raw
0.1
<0.1
<0.1
0.8
0.1
21.2
0.4
11.6
<0.1
0.2
0.4
34.9
Topside steak Lean, raw
<0.1
Loin steak or medallion Lean, raw <0.1b Fat, raw <0.1 Fillet Lean, raw <0.1 Rump steak Lean, raw Fat, raw
0.1
0.1
1.1
<0.1
22.4
0.4
11.0
<0.1
0.2
0.3
35.6
Silverside steak Lean, raw <0.1
<0.1
<0.1
1.1
<0.1
23.5
0.4
12.1
<0.1
0.2
0.3
37.5
Diced pork Raw
<0.1
<0.1
<0.1
1.2
<0.1
22.6
0.4
11.6
<0.1
0.1
0.2
36.0
Pork strips Raw
<0.1
<0.1
<0.1
1.1
<0.1
22.0
0.4
11.6
<0.1
0.1
0.2
35.5
Pork mince Raw
0.5
<0.1
<0.1
1.5
0.1
24.1
0.5
13.0
<0.1
<0.1
<0.1
39.8
Loin roast Lean, raw Fat, raw
<0.1 <0.1
0.1 <0.1
<0.1 <0.1
1.2 1.4
<0.1 0.1
23.4 24.1
0.5 0.7
12.2 13.1
<0.1 0.1
<0.1 <0.1
0.1 <0.1
37.4 39.5
Round (mini) roast Lean, raw <0.1 Fat, raw <0.1
<0.1 <0.1
<0.1 0.1
1.1 1.6
0.1 0.1
21.8 24.0
0.5 0.5
10.9 11.4
<0.1 <0.1
0.1 <0.1
0.3 <0.1
34.8 37.6
Scotch roast Lean, raw Fat, raw
0.1 <0.1
<0.1 <0.1
1.4 1.6
<0.1 <0.1
23.6 26.7
0.4 0.6
13.2 15.3
<0.1 0.1
<0.1 <0.1
<0.1 <0.1
38.7 44.2
<0.1 <0.1
Results are for a single composite for three Australian States (one analytical sample), single determinations. Limit of quantification 0.1%.
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composites. The apparent retention data for cholesterol on dryfrying were 100%, again consistent with cholesterol as an integral component of cell membranes.
3.2.2. Variability study of fatty acids composition of pork loin chop The data for saturated, monounsaturated and polyunsaturated fatty acid composition of loin chop are shown in Table 2 (% total), and Table 3 (specific acids as mg/100 g meat). The predominant saturated fatty acid in loin chop was C16:0, palmitic acid, followed by C18:0, stearic acid, with low amounts of C14:0 and there were slightly higher proportions of these acids in the separable fat than the separable lean (p = 0.01, 0.001, 0.008, respectively; Table 2). Differences between States for lean were only significant for C16:0 (Queensland and Victoria > Western Australia; p = 0.006). For the monounsaturated fatty acids in loin chop, the predominant acid was C18:1, oleic acid, with slightly higher proportions in the separable fat than the separable lean (p = 0.009), followed by C16:1, present in low proportions and slightly higher in lean than in fat (p < 0.001) (Table 2). There were no significant differences between States (p = 0.286, 0.951, respectively). The predominant polyunsaturated fatty acid in loin chop was linoleic acid, C18:2n-6, with higher proportions of this acid in the lean tissue from the Western Australian samples than those from Queensland and Victoria but lower proportions in the fat tissue of the samples from Victoria than those from the other two States (significant fat/lean State interaction; p = 0.037) (Table 2). These lean differences may be due to a higher proportion of lupin in pig feeds in Western Australia than elsewhere. Arachidonic acid, C20:4n-6, was the next most dominant acid with much higher levels in lean tissue than fat tissue, and no significant differences be-
tween the three States (p = 0.517). Alpha-linolenic acid, C18:3n-3, which was present at low levels (below 1% total acids) was significantly higher in the Western Australian samples than those from the other two States (p = 0.021). Other polyunsaturated acids were at low proportions (<1%). Table 3 shows some fatty acids of specific interest in loin chop as mg/100 g food. Amongst the n-3 fatty acids, eicosapentaenoic acid (EPA) was undetectable in the lean tissue of loin chop, whilst alpha-linolenic acid (ALA), docosapentaenoic acid (DPA) and docosahexaenoic acid were at low levels in the lean tissue i.e. between 5 and 13 mg/100 g. In the fat tissue these acids were at low levels from 10–50 mg/100 g apart from ALA which was present in the fat tissue at levels of 280–460 mg/100 g. Both conjugated linoleic acid, c-9, t-11 and C18:1t were present at low levels in the lean tissue of loin chop, at <10 mg/100 g, whilst levels in the fat tissue were >150 mg/100 g. Arachidonic acid, C20:4n-6, was present at levels of 40–100 mg/100 g in both lean and fat.
3.3. Representative study of lipid composition of 12 other pork cuts 3.3.1. Cholesterol content The data for cholesterol content of the 12 other pork cuts studied are shown in Table 1. Cholesterol levels in raw lean tissue ranged from 43 to 69 mg/100 g, whilst levels in raw fat tissue ranged from 38–76 mg/100 g. In general, as for loin chop, on a per cut basis, cholesterol levels were higher in the lean tissue than the fat tissue, probably reflecting the presence of cholesterol in cell membranes. Caution is needed in drawing conclusions from comparisons of raw and cooked cuts since the cuts were from different samples in each case, and only apparent cooking retentions could
Table 5 Monounsaturated fatty acids (MUFA) composition of 12 other pork cuts, raw, per cent total acidsa. C16:1
C17:1
C18:1
C18:1 9t
C20:1
C22:1
C24:1
Total MUFAb
3.4 2.3
0.6 <0.1
39.3 43.0
0.4 0.5
0.6 0.8
<0.1 <0.1
<0.1 0.2
44.3 46.8
3.4
<0.1
45.3
1.0
0.8
<0.1
<0.1
50.5
<0.1 <0.1
2.8 2.4
0.6 <0.1
38.2 45.0
0.4 0.6
0.6 0.8
<0.1 <0.1
<0.1 <0.1
42.6 48.8
Round steak Lean, raw
<0.1
2.4
1.2
34.5
0.4
0.6
<0.1
<0.1
39.1
Topside steak Lean, raw
<0.1
3.2
0.7
38.7
0.3
0.6
<0.1
<0.1
43.5
Silverside steak Lean, raw
<0.1
3.6
0.7
39.9
0.4
0.7
<0.1
<0.1
45.2
Diced pork Raw
<0.1
2.8
0.5
41.1
0.4
0.7
<0.1
<0.1
45.6
Pork strips Raw
<0.1
2.8
0.6
39.2
0.4
0.6
<0.1
<0.1
43.6
Pork mince Raw
0.3
2.8
0.1
42.0
0.7
0.7
<0.1
<0.1
46.6
Loin roast Lean, raw Fat, raw
<0.1 <0.1
2.8 2.4
0.4 <0.1
41.8 41.8
0.4 0.5
0.7 0.8
<0.1 <0.1
<0.1 <0.1
46.0 45.5
Round (mini) roast Lean, raw <0.1 Fat, raw <0.1
2.9 3.0
0.7 <0.1
38.4 43.9
0.4 0.5
0.7 0.8
<0.1 <0.1
<0.1 <0.1
43.0 48.1
Scotch roast Lean, raw Fat, raw
2.7 2.6
0.2 <0.1
42.0 43.1
0.4 0.6
0.7 0.8
<0.1 <0.1
<0.1 0.1
46.0 47.3
Cut
a b c
C14:1
Loin steak or medallion Lean, raw <0.1c Fat, raw <0.1 Fillet Lean, raw <0.1 Rump steak Lean, raw Fat, raw
<0.1 <0.1
Results are for single composites for three Australian States, (one analytical sample), single determinations. Includes C18:1 t1. Limit of quantification 0.1%.
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A.J. Sinclair et al. / Food Chemistry 121 (2010) 672–681
be calculated, not true cooking retentions (Murphy et al., 1975). However, apparent cholesterol retentions in both separable lean and separable fat were 100% during the dry-frying cooking process, but 90% during roasting, when data for all 13 cuts were considered together. 4.3.2. Fatty acids The fatty acids composition of the 12 other pork cuts are shown as percentage total in Table 4 (saturated), Table 5 (monounsaturated), Table 6 (polyunsaturated) and, expressed as mg/100 g meat, in Table 3 (specific fatty acids). Most of these cuts were very similar in composition to loin chop in terms of saturated and monounsaturated fatty acids. However, the overall composition of fatty acids in pork mince, pork strips and diced pork, indicated a mixture of lean and fat tissue, and the measured level of 0.5% for C4:0 in pork mince may have reflected cross-contamination from mincing machines. For the polyunsaturated fatty acids the results were very variable by cut, with higher overall levels of PUFA of a cut reflecting its higher levels of C18:2n-6. The biological significance of these differences cannot be determined from these data, and may simply reflect analytical variability only. 4. Discussion 4.1. Comparison of lipid composition across Australian States There were no differences in cholesterol composition between States, but small differences in fatty acid composition were seen between States, Western Australian lean samples having signifi-
cantly lower levels of C16:0 and significantly higher levels of C18:2n-6, and alpha-linolenic acid, C18:3n-3, possibly due to lupin in Western Australian pig feeds. 4.2. Comparison of lipids in present-day pork with assessments in the 80s and 90s 4.2.1. Cholesterol content In contrast to the data of the 80s (Hutchison et al., 1987) and 90s (Barnes et al., 1996), present-day pork has higher levels of cholesterol in the lean tissue than the fat tissue. Thus levels of cholesterol in lean tissue are similar to those of the 80s and 90s but are lower in the fat tissue at the present time, possibly due to the much higher moisture levels of present-day pork (23.8 g/100 g now vs 11.7 g/100 g in the 80s). It should be mentioned, however, that the cholesterol method used in the 80s was an enzymatic kit method, not GLC as in the present study and the study done in the 90s. 4.2.2. Fatty acid composition In the 80s the then analytical team at the University of New South Wales was commissioned to analyse pork by column chromatography for fatty acids with chain length and unsaturation up to C18:3 only and comparable data for the present study are therefore not available from Hutchison et al. (1987). However, data produced by capillary chromatography are available from Sinclair and O’Dea (1987) for some similar pork cuts. The proportion of DHA in the 1987 sample was lower than in the present study, although the total level of long-chain n-3 fatty acids was similar in both studies.
Table 6 Polyunsaturated fatty acids (PUFA) composition of 12 other pork cuts, raw, per cent total acidsa. Cut
C18:3n3
C20:2n6
C20:3n6
C20:3n3
Loin steak or medallion Lean, raw 12.1 0.1 Fat, raw 9.3 <0.1
0.5 0.6
0.4 0.4
0.5 <0.1
0.1 <0.1
Fillet Lean, raw
a
C18:3n6
C20:4n6
C20:5n3
C22:2n6
C22:4n6
C22:5n3
C22:6n3
Total PUFA
3.4 0.1
<0.1b <0.1
<0.1 <0.1
0.5 <0.1
0.6 <0.1
0.3 <0.1
18.4 10.4
9.1
<0.1
0.9
0.4
0.1
<0.1
0.5
<0.1
<0.1
0.1
0.1
0.1
11.3
Rump steak Lean, raw 14.0 Fat, raw 11.4
0.1 <0.1
0.7 0.8
0.4 0.5
0.5 <0.1
<0.1 0.1
3.4 0.2
<0.1 <0.1
<0.1 <0.1
0.4 <0.1
0.6 <0.1
0.3 <0.1
20.4 13.0
Round steak Lean, raw 17.5
0.2
0.7
0.4
0.6
<0.1
4.6
<0.1
<0.1
0.6
0.8
0.5
25.8
Topside steak Lean, raw 13.9
0.1
0.5
0.4
0.5
<0.1
3.7
<0.1
<0.1
0.4
0.6
0.4
20.6
Silverside steak Lean, raw 10.6
<0.1
0.4
0.4
0.5
<0.1
3.6
<0.1
<0.1
0.5
0.5
0.3
16.8
Diced pork Raw 13.2
<0.1
0.8
0.4
0.3
0.1
2.2
<0.1
<0.1
0.3
0.4
0.3
18.1
Pork strips Raw
b
C18:2n6
14.5
0.1
0.7
0.4
0.4
<0.1
3.1
<0.1
<0.1
0.4
0.5
0.3
20.5
Pork mince Raw 10.7
<0.1
0.8
0.4
0.2
0.1
0.8
<0.1
<0.1
0.2
0.2
0.2
13.6
Loin roast Lean, raw Fat, raw
<0.1 <0.1
0.8 0.9
0.4 0.5
0.3 <0.1
0.1 0.1
1.6 0.2
<0.1 <0.1
<0.1 <0.1
0.3 <0.1
0.3 0.1
0.2 0.1
16.2 14.7
Round (mini) roast Lean, raw 15.5 Fat, raw 11.8
0.1 <0.1
0.8 0.9
0.5 0.5
0.5 <0.1
0.1 0.1
3.1 0.3
<0.1 <0.1
<0.1 <0.1
0.4 0.1
0.6 0.1
0.4 0.1
22.0 13.9
Scotch roast Lean, raw 11.6 Fat, raw 7.3
<0.1 <0.1
0.8 0.4
0.4 0.4
0.2 <0.1
0.1 <0.1
1.2 <0.1
<0.1 <0.1
<0.1 <0.1
0.2 <0.1
0.3 <0.1
0.2 <0.1
14.9 8.1
12.2 12.8
Results are for single composites for three Australian States (one analytical sample), single determinations. Limit of quantification 0.1%.
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Table 7 Comparison of Australian pork and Australian red meats for selected fatty acids composition, raw, separable fat and separable lean, mg/100 g.
Red meat 2002 Beef – lean Beef – fat Veal – lean Veal – fat Lamb – lean Lamb – fat Mutton – lean Mutton – fat Pork 2005/6b Lean Fat Lean + fat
C18:1 trans
C20:4n-6
C18:3n-3 (ALA)
C20:5n-3 (EPA)
C22:5n-3 (DPA)
C22:6n-3 (DHA)
C18:2c9t11 (conjugated linoleic acid)
75 2428 22 2957 123 4850 102 2659
70 0 55 0 93 0 97 0
41 385 19 379 64 1444 100 1159
29 0 28 0 27 0 46 0
45 32 32 82 45 204 54 143
6 0 7 0 13 0 19 0
20 663 10 1224 46 1325 31 712
10 333 29
54 94 56
16 475 43
0 20 1
9 46 11
6 42 8
8 162 17
a
a
from Droulez et al. (2006). Concentrations are means over cuts with separable lean and fat components. Lean + fat are overall concentrations, obtained by weighting the concentrations in lean and fat in each component by the relative gross composition of lean and fat from Müller et al. (2009). b
Comparison of the fatty acids data from the present study with those from the study carried out in the 90s, which used pooled samples from several cuts (Barnes et al., 1996), is not possible because the text does not specify whether these pooled samples were fat, lean, or a mixture of both tissues. 4.3. Comparison of fatty acid composition of present-day pork with present-day red meats Nutrient profiling of animal products is an important strategy in their marketing in Australia. Table 7 therefore displays a comparison of the fatty acids composition of current pork and red meats (Droulez, Williams, Levy, Stobaus, & Sinclair, 2006). As expected, meat from pork, as a non-ruminant animal, had much lower levels of trans-acids than red meats from ruminant animals. Pork lean tissue compares unfavourably with lean tissue in red meats with respect to content of EPA, DPA, ALA and CLA. However, DHA levels of lean pork are only slightly lower than those of lean red meats. The Australian pigmeat industry has recently published the results of fishmeal feeding trials which significantly increased the EPA and DHA by fourfold or more with organoleptic profiles and stability comparable with those of regular pork (Sioutis et al., 2008). 4.4. Comparisons with pork data from other countries 4.4.1. Cholesterol content Comparisons with UK data (Food Standards Agency, 2008), Danish data (National Food Institute, 2008) and USDA data (Howe, Trainer, & Holden, 2007) show that the cholesterol data in the present study are in contrast since the cholesterol content of separable lean was higher than in separable fat. The reasons are unclear but may be due to method performance in this study, or to real differences in rearing and feeding of pigs in these other countries. 4.4.2. Fatty acid composition Comparisons with data for UK pork (Food Standards Agency, 2008) reveal that Australian pork would appear to be lower in levels of EPA, DPA and DHA since the UK food tables give levels of 0.01 g/100 g, 0.02 g/100 g and 0.01 g/100 g, respectively, for these acids in pork, trimmed lean, raw, probably reflecting feeding differences. Comparisons with US fresh pork, lean only, raw cannot be made as the latest release of USDA food composition data, SR 22, does not show values for these acids in these cuts (USDA, 2009). This observation also applies to the most up-to-date version of the Danish food composition tables (National Food Institute, Technical University of Denmark, 2008).
5. Conclusions This comprehensive study of national and cut variation of cholesterol and fatty acids in Australian pork appears to be the first such study published for this product and the data will contribute to the Australian food composition tables that are heavily used in dietary and food regulatory work. Cholesterol levels in separable lean were similar to those seen in more limited studies undertaken in previous decades, whilst cholesterol in separable fat had declined over the period. For fatty acids the study showed some variability in the polyunsaturated fatty acids composition by State which may have been due to feeding differences. However, the results may have been confounded by analytical variability and differences in the carcase location and configuration of cuts. Levels of DHA in separable lean were not as low as previously thought, but the levels of long-chain n-3 acids in pork are considerably lower than in Australian lean red meats. Industry efforts to improve the levels of these acids in pork appear justified especially given the high level of interest in improving the dietary intakes of these acids in Australia. Acknowledgments We wish to thank Janet Stark, Sharon Kennedy, Keith Pitts and Steve Humphries of FSA for technical assistance, dissection and processing of meat samples and Mendi Sulentic for data entry and data verification. Darryl D’Souza and Tami Macadam of APL provided additional advice. This study was funded by Australian Pork Limited. References AOAC International. (2005/2006). Official Methods of Analysis (OMA) (18th ed./ Revision 1). Arlington, VA: AOAC International. www.eoma.aoac.org; Accessed 10.07.07. Badings, H. T., & De Jong, C. (1983). Glass capillary gas chromatography of fatty acid methyl esters. A study of conditions for the quantitative analysis of short- and long-chain fatty acids in lipids. Journal of Chromatography, 279, 493–506. Barnes, J. A., Lewis, J. L., & Buick, D. R. (1996). Composition of new-fashioned pork 1994. Food Australia, 48(Suppl.), 1–15. Bligh, E. G., & Dyer, W. J. (1959). A rapid method for total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology, 3, 911–917. Christie, W. W. (1993). Preparation of ester derivatives of fatty acids for chromatographic analysis. In W. W. Christie (Ed.), Advances in lipid methodology (pp. 69–111). Dundee: Oily Press. Cobiac, L., Droulez, V., Leppard, P., & Lewis, J. (2003). Use of external fat width to describe beef and lamb cuts in food composition tables. Journal of Food Composition and Analysis, 16, 133–145. Department of Agriculture, Fisheries and Forestry. (2007).
A.J. Sinclair et al. / Food Chemistry 121 (2010) 672–681 Droulez, V., Williams, P., Levy, G., Stobaus, T., & Sinclair, A. J. (2006). Composition of Australian red meat 2002: 2. Fatty acid profile. Food Australia, 58, 335–341. Food and Agriculture Organization. (2009). Background to INFOODS.
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Howe, J. C., Trainer, D., & Holden, J. M. (2007). USDA nutrient data set for fresh pork (derived from SR), release 1.1*.