The effects of RN genotype and tumbling on processing yield in cured–smoked pork loins

MEAT SCIENCE Meat Science 67 (2004) 409–419 www.elsevier.com/locate/meatsci

The effects of RN genotype and tumbling on processing yield in cured–smoked pork loins €m Anja Hullberg *, Kerstin Lundstro Department of Food Science, Swedish University of Agricultural Sciences, P.O. Box 7051, SE-750 07 Uppsala, Sweden Received 17 September 2003; received in revised form 12 November 2003; accepted 14 November 2003

Abstract The objective was to investigate the effects of RN genotype and tumbling treatment on yields throughout the processing of cured– smoked loins. Furthermore, the economic outcome was calculated for the different treatments because the technological yield is important for the meat industry. The study comprised two separate trials, T1 and T2, and included loins from 62 and 32 female pigs crossbreed with Hampshire, respectively. All loins in T1 were tumbled, whereas half of the loins in T2 were tumbled and the remainder was non-tumbled. Glucose and glucose-6-phosphate concentrations in meat juice and drip loss were higher, and ultimate pH and technological yield lower in loins of the RN
carriers than those of non-carriers. Water loss during processing was largest at heating, when yield between RN genotypes differed the most for T2. Yield between genotypes differed the most at curing for T1. When tumbling was included in the processing the technological yield increased, but the RN allele was still negatively affected. Salt content in cured–smoked loins was higher in non-carriers than RN
carriers in T1, whereas salt content in non-tumbled non-carriers was significantly lower than in the other cured–smoked loins in T2. Tumbled cured–smoked loins contained more water than nontumbled loins. There were moderate to high correlations between ultimate pH and processing yields except for curing yield. Water content in the cured–smoked loins was positively related to technological yield. The differences between the two trials suggest that the process design greatly influences the final product. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: RN genotype; Tumbling treatment; Processing yield; Pork quality; Water-holding capacity

1. Introduction It is well known that one of the most important factors influencing meat quality is the water-holding capacity (Offer & Knight, 1988a). Besides the effects on meat quality the water content considerably affects the economic outcome because meat and meat products are sold by weight. The ability of meat to hold water is influenced by both genetic and environmental factors. Meat from pigs of the Hampshire breed, which greatly influences technological quality, was first described by Monin and Sellier (1985). Later, this ‘‘Hampshire effect’’ was found to originate in a dominant major gene referred to as the RN
allele (Le Roy, Naveau, Elsen, & Sellier, 1990; Naveau, 1986). The primary effect of the RN
allele

*

Corresponding author. Tel.: +46-18671985; fax: +46-18672995. E-mail address: [email protected] (A. Hullberg).

0309-1740/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2003.11.015

is increased levels of glycogen in glycolytic muscles (Fernandez, Tornberg, Naveau, Talmant, & Monin, 1992), causing low ultimate pH levels. This negatively affects the water-holding capacity of fresh meat and lowers the yield of processed meat products (Gari
epy, Godbout, Fernandez, Talmant, & Houde, 1999; Lundstr€ om, Andersson, & Hansson, 1996; Lundstr€ om, Enf€alt, Tornberg, & Agerhem, 1998a). When processing meat, a large amount of fluid is expelled from the meat tissue during cooking. The changing temperature during heating induces shrinkage of the meat structure, causing loss of fluid from the meat (Bouton, Harris, & Shorthose, 1976; Offer & Knight, 1988a). Moreover, other steps of the processing are involved in the water-holding capacity and therefore the processing design itself is important. One of the most common processing procedures in the meat industry is to cure and thereafter cook the meat. Curing causes swelling of myofibrils thereby enhancing the ability of

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the meat to retain water during heating (Offer & Knight, 1988a). The processing is often complemented with tumbling of the meat: a mechanical treatment after curing, which causes cellular disruption of the meat tissue (Bedinghaus, Ockerman, Parrett, & Plimpton, 1992; Cassidy et al., 1978; Lawlis, Plimpton, Ockerman, & Parrett, 1992). This alteration of the structure, together with curing ingredients, allows the meat to improve the yield (Chow, Ockerman, Cahill, & Parrett, 1986). The same modification of the structure promotes also migration of salt and nitrite into the meat and thereby favours a more even distribution of brine in the meat (Krause, Plimpton, Ockerman, & Cahill, 1978a). Further, it permits salt soluble proteins to move to the surface where they can create a sticky crust, which enhances muscle cohesion upon heating (Siegel, Theno, & Schmidt, 1978). Tumbling is also favourable from an eating point of view since tumbling results in a more tender and juicy meat (Dzudie & Okubanjo, 1999; Hullberg, Lundstr€ om, & Virhammar, 2002). The effect of the RN genotype on technological yield has been studied earlier, but there is only limited information on the yield in each single processing step (Andersson, Olsen, & Froestrup, 1997; Heyer, 2000; Le Roy et al., 2000; Lundstr€ om et al., 1998a). Moreover, the interactions between RN genotype and tumbling treatment are to our knowledge not studied at all so far. This study aimed to investigate the effects of RN genotype and tumbling treatment on processing yield of cured– smoked loins, both for each single step in the process and for the technological yield. Furthermore, the economic outcome was calculated for the different genotypes and treatments.

2. Material and methods 2.1. Material The study comprised two separate trials, T1 and T2, and included loins from 62 and 32 crossbred female pigs [Hampshire  (Swedish Landrace  Swedish Yorkshire)], respectively. Pigs were raised commercially and stunned by CO2 , and the average carcass weight was 81 kg (cold carcass without head and fore feet). As routine, pigs were shackled by the left hind leg between stunning and scalding. The M. longissimus dorsi (LD) from the right half of the carcass in T1 and from both sides in T2 were collected 24 h post mortem. Quality measurements on fresh meat were performed 48 h post mortem at the 5th–6th rib. About 96 h post mortem the remainder of the loin was cured–smoked according to commercial routines in Sweden. All loins were wrapped with plastic film, packed five loins per cardboard box and transported in a refrigerated lorry from the slaughterhouse to the processing plant.

2.2. Classification into RN genotype Initially, meat juice was collected for a rapid prediction of the RN phenotype (Lundstr€ om & Enf€ alt, 1997). The concentration of glucose and glucose-6-phosphate (G-6-P) in meat juice was determined with a quantitative enzymatic method (Glucose (HK), Procedure No. 16UV, Sigma Diagnostics). On the basis of the bimodal distribution found (Fig. 1), the observed valley between the two peaks was used to divide the animals into carriers (RN
=rnþ ) and non-carriers (rnþ =rnþ ) of the RN
allele. Pigs with glucose and G-6-P concentrations P40 lmol/ml meat juice were considered as carriers of the RN
allele and loins with concentrations below this value were considered as non-carriers. In Fig. 1, the distribution in T1 reflects the distribution of glucose and G-6-P of the Swedish slaughter pig population at the time of trial run. In T2, pigs were selected to get an even number of each RN genotype, e.g., pigs close to the threshold value were excluded from the study to avoid misclassification. Besides, RN genotypes were identified with a DNA test using the polymerase chain reaction (PCR) method described by Milan et al. (2000) to verify the RN phenotypic classification. Only one sample was misclassified when comparing the phenotypic classification with the genotypic classification, which was corrected for (Fig. 1). In T1, 43 pigs were genotyped as carriers of the RN
allele and 19 as non-carriers; in T2, 15 and 17 respectively. 2.3. Technological meat quality in fresh meat Technological meat quality in fresh meat was determined 48 h post mortem as pH, colour and drip loss. Ultimate pH (pHu ) was measured using a portable Knick (Knick, Berlin, Germany) equipped with a combination gel electrode (SE104, Knick, Berlin, Germany). After at least 1 h of blooming, surface meat colour of samples was determined with a colorimeter (Minolta Chroma Meter CR-300, Osaka, Japan) using the L  a  b  colour space, representing lightness (L ), redness (a ) and yellowness (b ). Water-holding capacity was measured as drip loss from slices stored horizontally on a grid in a standardised environment (+4 °C) for 4 days (Barton-Gade et al., 1994). 2.4. Processing and processing yield All loins were individually marked with plastic straps, to make it possible to identify each loin during handling and processing. 2.4.1. Trial 1 The loins were processed 96 h post mortem at a commercial processing plant and included in a commercial batch. They were cured by multi-needle injection

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419

Trial 1

411

Trial 2 Frequency

Frequency 15

7 6

10

rn+/rn+ RN −/rn+

5

5 4 3 2 1

0

0 0

(a)

10

20

30

40

50

60

70

µmol per ml

0

(b)

10

20

30

40

50

60

70

µmol per ml

Fig. 1. Distribution of glucose and glucose-6-phosphate concentrations in meat juice from M. longissimus dorsi and classification into RN genotypes according to DNA analysis for T1 (a) and T2 (b). A threshold value of 40 lmol glucose and glucose-6-phosphate per ml meat juice was chosen for RN phenotypic classification (- - - -), which resulted in one misclassified sample in T1.

with brine containing 16% nitrite saline (0.6% nitrite in the NaCl) to a quantity of about 16% of the initial loin weight. All loins were tumbled simultaneously for 4.5 h in a commercial tumbler, put in elastic nets, smoked and cooked during 4 h to an average internal temperature of 67 °C, and finally cooled to +4 °C. All transport and storing of the loins was performed in a cold environment. To determine the processing yields loins were weighed at each step of the process whereupon the yields were calculated according to the following formulas: Yield (%), accumulative from step to step: Yield after curing ¼ b=a  100 Yield after tumbling and resting ¼ c=a  100 Yield after cooking and smoking ¼ d=a  100 Differences in yield (D, %) between processing steps: Yield difference between initial weight and curing ¼ ðb=a  100Þ
100 Yield difference between tumbling/resting and curing ¼ ðc=b  100Þ
100 Yield difference between cooking/smoking yield and tumbling ¼ ðd=c  100Þ
100 Technological yield ¼ ðd=a  100Þ
100 where a is the initial weight at the slaughterhouse before transportation to the processing plant (g), b is the weight after curing (g), c is the weight after tumbling or resting (g) and d is the weight after cooking and smoking (g). 2.4.2. Trial 2 In this trial the loins were processed in an experimental processing plant. Most of the brine, containing 16% nitrite saline (0.6% nitrite in the NaCl), was added by multi-needle injection and the final brine content was adjusted by manual injection. To get an equal salt content in the final product, irrespective of tumbling treatment, loins to be tumbled were injected to 16% of initial loin weight and non-tumbled loins to 17% of initial loin weight. The loins from the right side of the carcasses were tumbled for 4 h at +8 °C. For this purpose three smaller tumblers were used with 5–6 loins per

tumbler and occasion. The tumbling was carried out under constant vacuum (80–100 kPa) in intervals of 15min work, with eight revolutions per min, and 5-min rest periods. The two RN genotypes were, unlike in T1, tumbled in separate tumbling batches. Loins from the left carcass side were held in covered plastic trays at +4 °C while the other loins were tumbled (resting). All loins were put in elastic nets and then simultaneously smoked and cooked to an average internal temperature of 68 °C for 3.5 h before cooling to +4 °C. All transport and storing of the loins was performed in a cold environment. To determine the processing yields loins were weighed at each step of the process and the yields were calculated according to the formulas above. 2.5. Salt and water content One slice of each cured–smoked loin (70–100 g) was trimmed from fat and crust and analysed for salt (T1 and T2) and water content (T2). Only 30 loins (15 of each RN genotype) were analysed for salt content in T1. The salt content was measured with a chloride analyser based on conductivity titration (Corning 926, Chloride Analysator, Corning Ltd., Halstead, UK) in T1 and with a chloride titrator (CMT 10, Radiometer, Copenhagen) in T2. The water content was calculated based on analysis of dry-matter content. 2.6. Calculation of economic outcome The economic outcome was calculated in Euro ( ) based on the present prices on the Swedish market for boneless cured–smoked loin. The loss in income per kilogram fresh loin when it is processed, if the fresh meat comes from RN
carriers instead of non-carriers or if tumbling is excluded, is calculated as the difference in final loin weight between treatments with an initial loin weight of 1 kg times the retail price per kilogram cured– smoked loin.

412

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419

2.7. Statistical analysis Data were analysed using the MIXED procedure, Statistical Analysis System, release 8.2 (SAS Institute Inc., Cary, NC). The statistical models used included the fixed effects of RN genotype (T1 and T2) and tumbling treatment (T2), and the random effect of animal (T2). Interactions between fixed effects were included in the model when significant. Initial weights of fresh loins were included as a covariate when significant. To avoid overestimation of the degree of freedom Pearson correlation coefficients between ultimate pH, salt and water content in processed loins and processing yields were calculated on mean values per animal in T2, regarding RN genotypes. Correlations within tumbling treatment were calculated for each subgroup.

and 1.1% points higher for RN
carriers than non-carriers in T1 and T2, respectively. Fresh loins from RN
carriers were more reddish and yellowish in colour compared with non-carriers and for T2 the former were also significantly lighter. Initial loin weight was in T2 on average 189 g higher for left side loins (not to be tumbled) compared with right side loins (to be tumbled) (P ¼ 0:001) (Table 1). All animals except three had a heavier loin on the left side of the carcass; probably an unconscious and consistent difference in cutting and preparing left and right loins. A slight significant difference in pHu was found between left and right side loins in T2, with a 0.03 higher pHvalue in right side loins. RN genotype and fresh loin side did not interact significantly regarding technological fresh meat quality. 3.2. Processing yields

3. Results 3.1. Technological meat quality During the transport from the slaughterhouse to the processing plant, each loin had an average weight loss of 79 g (rnþ =rnþ ) and 111 g (RN
=rnþ ) in T1 and 35 g (rnþ =rnþ ) and 52 g (RN
=rnþ ) in T2. The purge was significantly greater from loins of RN
carriers than those of non-carriers in both trials (P ¼ 0:001 and P ¼ 0:004, respectively). The glucose and G-6-P concentrations were considerably higher in meat juice from RN
carriers than non-carriers (Table 1). The lower glucose and G-6-P concentration for non-carriers in T2 compared with T1 is an effect of excluding loins with glucose and G-6-P concentrations close to the threshold value in T2. In both trials, RN
carriers had significantly lower pHu values than non-carriers. Drip loss was 1.3%

The technological yield, i.e., the ratio between initial weight of the loin and the weight of the final product was 2.7% and 4.8% points lower in cured–smoked loins from RN
carriers compared with non-carriers in T1 and T2, respectively (Table 2). This difference was in T1 mainly caused during the curing procedure even though a minor difference between RN genotypes was observed in cooking/smoking yield. In T2, the major difference in processing yield between RN genotypes occurred during the cooking/smoking procedure. Tumbling/resting slightly, but significantly, affected yield in T2 in advantage of non-carriers of the RN
allele, which was not observed in T1. The curing step was not affected by RN genotype in T2. When tumbling was included in the process, the technological yield increased with 2.4% points (Table 3). The greatest difference in yield between tumbled and

Table 1 Technological properties of fresh loins according to RN genotype (T1 and T2) and planned tumbling treatment (T2) (least-square means  SE) P -value

Trial 1 þ

Glucose + G-6-P (lmol/ml meat juice)a Fresh weight of loin (g) pHu Drip loss (%) Colour L a b a

þ




þ

rn =rn , n ¼ 19

RN =rn , n ¼ 43

27.7  1.8

57.8  1.2

2884  66

P -value

Trial 2 þ

þ




þ

rn =rn , n ¼ 34

RN =rn , n ¼ 30

0.001

15.5  1.0

51.7  1.1

3038  44

0.055

2643  67

5.54  0.01 5.0  0.3

5.45  0.01 6.3  0.2

0.001 0.002

48.6  0.5 5.8  0.3 2.8  0.2

49.3  0.4 6.8  0.2 3.4  0.1

0.253 0.003 0.001

P -value

Trial 2 Not to be tumbled (left side), n ¼ 32

To be tumbled (right side), n ¼ 32

0.001

–

–

–

2657  71

0.885

2745  50

2556  50

0.001

5.53  0.02 3.4  0.4

5.41  0.02 4.5  0.4

0.001 0.042

5.45  0.01 3.7  0.3

5.48  0.01 4.2  0.3

0.050 0.277

47.5  0.5 6.8  0.3 2.2  0.2

49.5  0.5 8.5  0.3 3.9  0.2

0.009 0.001 0.001

48.6  0.4 7.8  0.2 3.2  0.2

48.5  0.4 7.5  0.2 2.9  0.2

0.798 0.106 0.103

Bold P -values indicate significant differences between RN genotypes and planned tumbling treatments, respectively (P 6 0:05). One measurement per pig.

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419

413

Table 2 Processing yields and differences in yield of individual processing steps (D) of cured–smoked loins with or without the RN
allele in T1 and T2 (leastsquare means  SE) P -value

Yield (%) þ

þ




43

þ




þ

rn =rn

RN =rn

0.001 0.001 0.001 –

15.6  0.5 4.4  0.3 )12.0  0.2 6.1  0.6

12.6  0.3 4.9  0.2 )12.5  0.1 3.4  0.4

0.001 0.180 0.046 0.001

0.135 0.020 0.001 –

15.4  0.3 )0.6  0.2 )11.5  0.3 1.5  0.6

14.8  0.3 )1.4  0.2 )14.6  0.4 )3.3  0.6

0.135 0.004 0.001 0.001

19

115.6  0.5 120.9  0.5 106.1  0.6 –

Trial 2 N Processing yield (%) After curing After tumbling or resting After cooking/smoking Technological yield (%)

P -value

D (%) þ

RN =rn

rn =rn Trial 1 N Processing yield (%) After curing After tumbling or resting After cooking/smoking Technological yield (%)

þ

34

112.6  0.3 118.1  0.3 103.4  0.4 – 30

115.4  0.3 114.7  0.4 101.5  0.6 –

114.8  0.3 113.2  0.4 96.7  0.6 –

Bold P -values indicate significant differences between RN genotypes (P 6 0:05).

Table 3 Processing yields and differences in yield of individual processing steps (D) of tumbled (n ¼ 32) and non-tumbled (n ¼ 32) cured–smoked loins in T2 (least-square means and SE) P -value

Yield (%)

Processing yield (%) After curing After tumbling or resting After cooking/smoking Technological yield (%)

Non-tumbled

Tumbled

115.2  0.2 113.9  0.3 97.9  0.5 –

114.9  0.2 113.9  0.3 100.3  0.5 –

0.200 0.948 0.001 –

P -value

D (%) Non-tumbled

Tumbled

15.2  0.2 )1.2  0.1 )14.1  0.3 )2.1  0.5

14.9  0.2 )0.8  0.1 )12.0  0.3 0.3  0.5

0.200 0.067 0.001 0.001

Bold P -values indicate significant differences between RN genotypes (P 6 0:05).

non-tumbled loins was caused during the cooking/ smoking phase, but tumbling also tended to diminish the fluid loss during the tumbling/resting phase. For clarity, the individual subgroups (RN genotype/tumbling treatment) from T2 are presented in Fig. 2.

Technological yield, %

105

d c

100

b a

95

rn+/rn+, non-tumbled rn+/rn+, tumbled RN-/rn+, non-tumbled RN-/rn+, tumbled

90 Fig. 2. Technological yield in tumbled and non-tumbled cured–smoked loins of different RN genotypes in T2. Different letters indicate significant differences (P < 0:05) between experimental groups.

3.3. Salt and water content The salt content in slices of cured–smoked loins was in T1 significantly higher for non-carriers compared with RN
carriers (P ¼ 0:039) (Fig. 3). In T2, there was a significant interaction between RN genotype and tumbling treatment (P ¼ 0:035) (Fig. 3), because tumbled cured–smoked loins from non-carriers of the RN
allele contained less salt than the other loins. This interaction did not exist for water content, but tumbled cured–smoked loins contained more water than nontumbled cured–smoked loins (P ¼ 0:001) (Fig. 4). Water content did not differ significantly between RN genotypes (P ¼ 0:576). 3.4. Correlations between processing yields and pH, salt and water content Pearson correlation coefficients between ultimate pH, salt and water content and processing yields are shown in Table 4. A significant, but moderate, positive relationship was observed between pHu and technological

414

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419 Table 4 Pearson correlation coefficients between ultimate pH, salt and water content and processing yields, across and within RN genotypes and tumbling treatments (see Table 1 for number of observations) Technological Curing Tumbling Cooking/ yield yield yield smoking yield pHu Trial 1 Overall rnþ =rnþ RN
=rnþ

Fig. 3. Effect of RN genotype (T1 and T2) and tumbling treatment (T2) on salt content in cured–smoked loins. Different letters above individual bars indicate significant differences (P < 0:05) between experimental groups.

75

Water content, %

b 74 73 72

a

rn+/rn+ RN −/rn+ non-tumbled tumbled

71 70

RN genotype Tumbling treatment Fig. 4. Water content in tumbled and non-tumbled cured–smoked loins of different RN genotypes in T2. Different letters indicate significant differences (P < 0:05) between experimental groups.

yield across RN genotypes in T1. In T2, this positive correlation was much stronger and almost twice that in T1. The correlations within RN genotypes differed between trials. In T1, there was no relationship at all between pHu and technological yield for non-carriers, whereas there was a significant correlation among RN
carriers. This difference between RN genotypes was absent in T2, where a strong correlation was present between pHu and technological yield for both RN genotypes. A significant correlation was also found between pHu and cooking/smoking yield, as well as between pHu and tumbling yield in T2. A moderate correlation between salt content and technological yield across both RN genotypes was found in T1, but not in T2 (Table 4). However, this positive relationship was only present in loins from RN carriers. The significant correlation found between salt content and curing yield across both RN genotypes in T1 originated from RN
loins. For water content there was a moderate to high positive relationship with technological yield.

0.43 )0.06 0.44

0.32 )0.21 0.20

0.14 0.24 0.17

0.21 )0.02 0.32

Trial 2 Overall rnþ =rnþ RN
=rnþ Non-tumbled Tumbled

0.81 0.71 0.71 0.78 0.70

0.26 0.22 0.37 0.29 0.13

0.62 0.33 0.62 0.51 0.45

0.76 0.55 0.60 0.75 0.67

Salt content Trial 1 Overalla rnþ =rnþ RN
=rnþ

0.44 0.06 0.53

0.53 0.09 0.64

0.10 0.16 0.15

)0.10 )0.18 )0.19

Trial 2 Overall rnþ =rnþ RN
=rnþ Non-tumbled Tumbled

0.01 0.37 0.25 0.11 )0.16

0.56 0.72 0.42 0.62 0.19

0.32 0.38 0.63 0.25 0.17

)0.26 )0.26 )0.04 )0.11 )0.39

Water content Trial 2 Overall rnþ =rnþ RN
=rnþ Non-tumbled Tumbled

0.37 0.73 0.51 0.42 0.30

0.41 0.53 0.07 0.42 0.34

0.23 0.41 0.17 0.16 0.23

0.24 0.30 0.61 0.34 0.11

Bold correlation coefficients indicate significant correlations (P 6 0:05). a Number of observations for T1 was: overall ¼ 30; rnþ =rnþ ¼ 15; RN
=rnþ ¼ 15.

Ultimate pH was moderately to highly correlated to all processing yields except curing yield for both tumbling treatments (Table 4). Salt content was only related to curing yield in non-tumbled loins. There was a moderate correlation between water content and technological and curing yields for non-tumbled cured–smoked loins. Drip loss was negatively correlated to both technological yield and pHu in T1 ()0.42; P ¼ 0:001 for both), while in T2 these correlations were not significant ()0.18; P ¼ 0:312 and )0.34; P ¼ 0:056, respectively). 3.5. Economic outcome The retail price per kilogram cured–smoked loin, converted from the present price for the product on the Swedish market into Euro ( ), was 6.4 . Because of the lower processing yield of RN
carriers, the loss of income compared with non-carriers was 0.17 and 0.31

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419

/kg fresh loin processed for T1 and T2, respectively. When tumbling was excluded from the processing, the income per kilogram fresh loin processed decreased with 0.15 .

4. Discussion Quality and characteristics of the final meat product are greatly influenced by the design of the meat processing (Schmidt, 1984). The large difference in the level of technological yields between trials (5–6% points) in the present study can hence be explained by the processing procedure. In T1, loins were tumbled together with a redundancy of brine, whereas in T2, the only brine included in the tumbler was the injected brine (brine and meat juice lost between injection and the fill up of the tumblers). Thus, there was no possibility for loins in T2 to gain in weight. As a consequence, the technological yield for tumbled loins could be expected to have been larger and the difference between tumbled and non-tumbled loins even more pronounced if an excess of brine had been added during tumbling. The reason for not adding a redundancy of brine in T2 was the aim to produce final products with an equal salt content between tumbled and non-tumbled loins. However, this clearly indicates the importance of tumbling loins in an excess of brine to exploit the positive effects given by tumbling on processing yields. The differences in processing yields between RN genotypes arose at different processing steps in the two trials. Processing yields in T2 were more in accordance with previous studies where no tumbling was included in the processing (Heyer, 2000; Le Roy et al., 2000; Lundstr€ om et al., 1998a), with the main differences between RN genotypes in the cooking step. In T1, however, RN genotypes differed most in curing yield, which partly could be explained by the time gap between cutting and processing. Loins from RN
carriers accounted for the larger losses and thus had a lower yield even before the processing started. If the weight of the loins at the arrival at the processing plant was used as initial weight instead of the weight at the slaughterhouse in T1, there would still be a significant, but clearly smaller difference between RN genotypes in curing yield (rnþ =rnþ 118.7%; RN
=rnþ 117.0%; P ¼ 0:001). Cooking normally generates the greatest release of fluid from the meat during the processing. This is because meat undergoes large structural changes on heating (Offer & Knight, 1988a). There are several different suggestions why RN
carriers lose more fluid than noncarriers on heating. Electron micrographs of cooked ham samples showed that the bonds between actin filaments and Z-lines were often ruptured in RN
carriers, whereas these bonds were still intact in non-carriers (Monin, 1995). Higher slicing losses in processed meat

415

from Hampshire pigs with low ultimate pH (<5.5) compared to pigs with high ultimate pH further supports the notion of a looser ultra structure in RN
carriers (Chevillon et al., 1994). This modified structure of meat from RN
carriers can presumably increase the release of fluid from the meat tissue. However, a more frequently discussed theory is the higher loss of glycogen-bound water during heating (Fernandez, Lefaucheur, Gueblez, & Monin, 1991). Glycogen is believed to bind water 2–4 times its own weight (Greenleaf, Olsson, & Saltin, 1969), which is about the same as for muscle proteins (Sellier & Monin, 1994). The redundancy of glycogen in combination with a lower protein content in RN
carriers results in a higher water/protein ratio (6%) in these animals (Monin, Brard, Vernin, & Naveau, 1992). Thus, more of the water in meat from RN
carriers is bound to glycogen, at the same time as there is less protein to hold the excess of water, the water is more easily expelled during heating when the protein matrix shrinks (Fernandez et al., 1991). Recently another theory was presented. Differential scanning calorimetry analyses on protein denaturation in pork muscle tissue during heating suggested that the low water-holding capacity of meat from RN carriers is caused by high degree of denaturation of myosin tails and sarcoplasmic proteins (Deng et al., 2002). Lundstr€ om et al. (1996) found a smaller amount of total and sarcoplasmic proteins in RN
carriers, possibly indicating a slightly higher degree of protein denaturation postmortem and thus, a decreased water-holding ability. By following the physical–chemical state of water in the meat during heating with low-field NMR transverse relaxation measurements, Bertram, Engelsen, Busk, Karlsson, and Andersen (2004) found a significant difference in transition in water properties between RN genotypes at a heating temperature of 43 °C, when the myosin is believed to begin to denature. Therefore, the authors agreed with the findings by Deng et al. (2002) and suggested that it is more likely the heat-sensitive proteins in RN
carriers that lower the water-holding capacity in this meat at heating. However, the most feasible explanation is probably a combination of the above theories: a low capacity of the heat-sensitive proteins to hold the excess of water caused by the high glycogen content and a poor ultra structure that more easily releases drip. Moreover, as found in the present study, purge in fresh meat differs considerably between RN genotypes (Moeller, Baas, Leeds, Emnett, & Irvin, 2003), which is not explained by the heat-sensitive proteins, but may be explained by the higher glycogen and lower protein content in meat from RN
carriers. Besides, pH considerably affects water-holding capacity (Bendall & Swatland, 1988; Offer & Knight, 1988b). When studying the relationship between ultimate pH and yield in the present study, a positive correlation can be noted across RN genotypes for technological yield in both trials.

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However, there was no relationship between technological yield and ultimate pH across RN genotypes in the study by Gari
epy et al. (1999). Nevertheless, when studying correlations between the Napole yield, an indicator of the technological yield of cured-cooked ham processing (Naveau, Pommeret, & Lechaux, 1985), and ultimate pH, Lundstr€ om et al. (1996) and Gari
epy et al. (1999) found positive relationships both across and within RN genotypes. M€ uller (1991) found a relationship between processing yield and ultimate pH when dividing the hams into groups prior to ultimate pH. The above results indicate the influence of ultimate pH on processing yields, but the pre-rigor pH development might be more important than the ultimate pH regarding water-holding properties (Rosenvold et al., 2001; Sch€ afer, Rosenvold, Purslow, Andersen, & Henckel, 2002). Unfortunately the early postmortem pH was not measured in the present study. A more rapid pH fall in RN
carriers compared to non-carriers was reported recently (Josell, Martinsson, & Tornberg, 2003a; Josell, von Seth, & Tornberg, 2003b), which besides the lower ultimate pH, may explain the differences in the holding of fluid between RN genotypes. Tumbling increased the technological yield from 97.9% to 100.3%, which is in agreement with the findings of Chow et al. (1986) and Krause, Ockerman, and Cahill (1978b). Moreover, tumbling tended also to increase the tumbling yield. Lawlis et al. (1992) reported decreased tumbling yield after 3 and 6 h of tumbling of sectioned and formed ham compared with non-tumbled ham and suggested it was caused by unrecovered exudates and moisture loss. In the present study, this loss was probably covered by the non-tumbled loins large purge during resting. Prediction of RN phenotype in meat juice by the method of Lundstr€ om and Enf€ alt (1997) is a relatively reliable analysis. This, in combination with the ease and quickness the method provides, makes it an excellent preliminary predictor of RN phenotype while waiting for final genotype determination by DNA test. Only one sample in T1 (1.6%) was misclassified when compared to the genotypic classification based on DNA in muscle tissue, which is in accordance with Lundstr€ om and Enf€ alt (1997) who found 1.9% wrongly classified samples when glucose and glucose-6-phosphate in meat juice were compared with glycolytic potential in muscle (glycogen, glucose, glucose-6-phosphate and lactate). Heyer (2000) detected 4% misclassified samples when comparing meat juice concentrations of glucose and G-6-P with the DNA analysis by Milan et al. (2000). The frequency of RN
carriers observed in T1 (69%) closely agreed with earlier findings (Andersson, Olsson, Hullberg, & Lundstr€ om, 2003; Heyer, 2000; Josell, Martinsson, Borggaard, Andersen, & Tornberg, 2000; Josell et al., 2003a, 2003b), but was somewhat higher than for the Swedish slaughter pig population reported

earlier (Enf€alt, Lundstr€ om, Karlsson, & Hansson, 1997b; Lundstr€ om et al., 1996; Lundstr€ om et al., 1998b). For both trials the differences in ultimate pH and drip loss values between RN genotypes agree with previous results (Enf€alt, Lundstr€ om, Hansson, Johansen, & Nystr€ om, 1997a, 1997b; Lundstr€ om et al., 1998a). The difference in ultimate pH between loins from the right and left side in T2 could be an effect of shackling procedure. In the abattoir used, the common procedure is to shackle pigs in their left hind leg between stunning and scalding. The weight of the carcass appears to have stimulated the muscles on the shackling side, resulting in lower ultimate pH in the left side loins. Fischer and Augustini (1981) found lower pH 45 min postmortem in ham muscles of shackled sides, even though this difference between sides was counterbalanced 24 h after slaughter and no influence of shackle side on M. longissimus dorsi was observed. Surface colour of fresh loins from RN
carriers was more reddish and yellowish in the present study, as found earlier (Lindahl et al., 2004; Olsson, Andersson, Hansson, & Lundstr€ om, 2003). However, the results differ between studies. Le Roy et al. (2000) found a more red meat surface from RN
carriers, while Hamilton, Ellis, Miller, McKeith, and Parrett (2000), Miller, Ellis, McKeith, Bidner, and Meisinger (2000) and Deng et al. (2002) could detect no differences in redness between RN genotypes. The lighter surface colour found in loins from RN
carriers in T2, but not in T1, was also observed earlier (Gari
epy et al., 1999; Hamilton et al., 2000; Le Roy et al., 2000). Lack in differences between RN genotypes of L values, as in T1, was recorded by Miller et al. (2000), Deng et al. (2002) and Olsson et al. (2003). M€ uller (1991) stated that the salt concentration positively influenced the yield of cooked hams up to levels of 2.2%; above this level no further advantages were to be observed. In the present study, the salt concentrations in the cured–smoked loins were higher in T2 than in T1, but both trials had average salt concentrations above 2.2%. Still, there were positive correlations between salt contents and curing yields. However, the results are contradictory because the correlations found between salt content and curing yield can be ascribed purely to loins from RN
carriers in T1, but for T2 this correlation is mainly found for loins from non-carriers. These differences within RN genotypes could be due to the variation in salt content, because in T1, rnþ =rnþ loins contained more salt than RN
=rnþ loins, whereas in T2 salt content did not differ between RN genotypes when the loins were tumbled. The higher salt content in non-carriers compared with carriers found in T1 contradicts earlier results (Eber & M€ uller, 1999), where processed meat from RN
carriers was saltier, or no differences between RN genotypes were detected (Lundstr€ om et al., 1998a). Eber and

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419

M€ uller (1999) suggested that the fluid lost from the meat contains lower concentrations of salt than the injected brine, and that there would therefore be a greater salt accumulation in RN
carriers. Other explanations for the variable results observed in the literature could be the ratio of free and bound fluid in the meat, the process design and the salt content. The technological yield was as much as 2.7–4.8% points higher in loins from non-carriers than from RN
carriers. Heyer (2000), Le Roy et al. (2000) and Lundstr€ om et al. (1998a) reported similar differences in technological yield in hams (2.7%, 2.2% and 4.1% points, respectively). When tumbling was included in the process, the technological yield increased in the final product as expected (Dzudie & Okubanjo, 1999; Pietrasik & Shand, 2002), as did the final water content. The difference in technological yield due to tumbling (2.4% points) was not as high as the difference for RN genotype. The maximal income difference occurred between non-tumbled RN
carriers and tumbled non-carriers in T2 and was 0.47 /kg fresh loin processed (not shown). If we simplify the situation by assuming the same technological yield from all cuts of the carcass (80 kg) containing 60% meat and that 75% of the meat is processed and the average loss in price per kilogram is 0.17 (as in T1), there would be a price loss per carcass of 6.1 . For every million slaughtered pigs, the industry would lose 6.1 million . Hence, even small changes in the technological yield (2.7% points) considerably affect the economic outcome of the meat industry.

5. Conclusion Meat from RN
carriers had inferior water-holding properties compared to meat from non-carriers. Incorporating tumbling in the process positively affected the technological yield of cured–smoked loins. There were no significant interactions between RN genotype and tumbling treatment for any measured variable in the present study except salt content, suggesting that the differences in meat quality between RN genotypes cannot be overcome by including tumbling in the process. Further, the large differences between the two trials in processing yields clearly illustrate the influence of the process design on the final product.

Acknowledgements We thank Dr. Ingemar Hansson for excellent assistance at the slaughterhouse. Moreover, Mr. Stein Andersson and his co-workers at Farmek in Link€ oping are gratefully acknowledged for their valuable help with processing the loins in T1. We are also grateful to Mr. Jonas Bj€ arstorp at former Swedish Meats R&D, K€ avlinge

417

for providing us with the possibility to process our meat at their experimental processing plant and for skilful help during the processing of the meat in T2. This work was supported by the LiFT programme (Future Technologies for Food Production), financed by the SSF (Foundation for Strategic Research) in Sweden.

References Andersson, M., Olsen, E.V., & Froestrup, A. B. (1997). Relationship between raw material quality and production yield of cooked hams manufactured without the use of phosphates. In Proceedings of the 43th international congress of meat science and technology (pp. 358– 359), Auckland, New Zealand. Andersson, K., Olsson, V., Hullberg, A., & Lundstr€ om, K. (2003). Effects of sex, feed and pre-slaughter routines on technological meat quality in carriers and non-carriers of the RN
allele. Acta Agriculturae Scandinavica, A, Animal Science, 53, 147–154. Barton-Gade, P. A., Demeyer, D., Honikel, K. O., Joseph, R. L., Poulanne, E., Severine, M., Smulders, F., & Tornberg, E. (1994). Final version (I) of reference methods for water holding capacity in meat and meat products: Procedures recommended by OECD working group. In Proceedings of the 40th international congress of meat science and technology (pp. S–V.05), The Hague, The Netherlands. Bedinghaus, A. J., Ockerman, H. W., Parrett, N. A., & Plimpton, R. F. (1992). Intermittent tumbling affects quality and yield in prerigor sectioned and formed ham. Journal of Food Science, 57, 1063–1065, 1092. Bendall, J. R., & Swatland, H. J. (1988). A review of the relationships of pH with physical aspects of pork quality. Meat Science, 24, 85– 126. Bertram, H. C., Engelsen, S. B., Busk, H., Karlsson, A. H., & Andersen, H. J. (2004). Water properties during cooking of pork studied by low-field NMR relaxation – Effects of curing and the RN-gene. Meat Science, 66, 437–446. Bouton, P. E., Harris, P. V., & Shorthose, W. R. (1976). Dimensional changes in meat during cooking. Journal of Texture Studies, 7, 179– 192. Cassidy, R. D., Ockerman, H. W., Krol, B., Van Roon, P. S., Plimpton, R. F. J., & Cahill, V. R. (1978). Effect of tumbling method, phosphate level and final cook temperature on histological characteristics of tumbled porcine muscle tissue. Journal of Food Science, 43, 1514–1518. Chevillon, P., Boulard, J., Le Jossec, Ph., K
erisit, R., Sala€ un, Y., Alviset, G., & Vidal, E., (1994). Influence of ultimate pH and breed on the slicing losses of high-quality cooked hams to be sold prepacked. In Proceedings of the 40th international congress of meat science and technology (pp. 1–9). The Hague, The Netherlands. Chow, H. M., Ockerman, H. W., Cahill, V. R., & Parrett, N. A. (1986). Evaluation of cured, canned pork shoulder tissue produced by electrical stimulation, hot processing and tumbling. Journal of Food Science, 51, 288–291. Deng, Y., Rosenvold, K., Karlsson, A. H., Horn, P., Hedegaard, J., Steffensen, C. L., & Andersen, H. J. (2002). Relationship between thermal denaturation of porcine muscle proteins and water-holding capacity. Journal of Food Science, 67, 1642–1647. Dzudie, T., & Okubanjo, A. (1999). Effects of rigor state and tumbling time on quality of goat hams. Journal of Food Engineering, 42, 103– 107. Eber, M., & M€ uller, W. D. (1999). Studies on the suitability of Hampshire-type meat for processing cooked ham. Fleischwirtschaft International, 1, 19–22.

418

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419

Enf€ alt, A. C., Lundstr€ om, K., Hansson, I., Johansen, S., & Nystr€ om, P. E. (1997a). Comparison of non-carriers and heterozygous carriers of the RN
allele for carcass composition, muscle distribution and technological meat quality in Hampshire-sired pigs. Livestock Production Science, 47, 221–229. Enf€ alt, A. C., Lundstr€ om, K., Karlsson, A., & Hansson, I. (1997b). Estimated frequency of the RN- allele in Swedish Hampshire pigs and comparison of glycolytic potential, carcass composition, and technological meat quality among Swedish Hampshire, Landrace, and Yorkshire pigs. Journal of Animal Science, 75, 2924–2935. Fernandez, X., Lefaucheur, L., Gueblez, R., & Monin, G. (1991). Paris ham processing: Technological yield as affected by residual glycogen content of muscle. Meat Science, 29, 121–128. Fernandez, X., Tornberg, E., Naveau, J., Talmant, A., & Monin, G. (1992). Bimodal distribution of the muscle glycolytic potential in french and swedish populations of hampshire crossbred pigs. Journal of the Science of Food and Agriculture, 59, 307–311. Fischer, K., & Augustini, C. (1981). H€alftenunterschiede in der Fleischbeschaffenheit beim Schwein durch einseitiges H€angen w€ ahrend des Schlachtprozesses. Fleischwirtschaft, 61, 1187–1189. Gari
epy, C., Godbout, D., Fernandez, X., Talmant, A., & Houde, A. (1999). The effect of RN gene on yields and quality of extended cooked cured hams. Meat Science, 52, 57–64. Greenleaf, J., Olsson, K. E., & Saltin, B. (1969). Muscle glycogen content and its significance for the water content of the body. Acta Physiologica Scandinavia (Suppl. 330), 86 (Abstract). Hamilton, D. N., Ellis, M., Miller, K. D., McKeith, F. K., & Parrett, D. F. (2000). The effect of the Halothane and Rendement Napole genes on carcass and meat quality characteristics of pigs. Journal of Animal Science, 78, 2862–2867. Heyer, A. (2000). Influence of the RN
allele on production yield of warm smoked ham. Department of Food Science, Swedish University of Agricultural Sciences, Erasmus project, Publication 118 (59 p.). Hullberg, A., Lundstr€ om, K., & Virhammar, K. (2002). The effects of RN genotype and tumbling on sensory and technological meat quality of cured–smoked loins. In Proceedings of the 48th international congress of meat science and technology (pp. 338–339), Rome, Italy.  Martinsson, L., Borggaard, C., Andersen, J. R., & Josell, A., Tornberg, E. (2000). Determination of RN
phenotype in pigs at slaughter-line using visual and near-infrared spectroscopy. Meat Science, 55, 273–278.  Martinsson, L., & Tornberg, E. (2003a). Possible mechaJosell, A., nism for the effect of the RN
allele on pork tenderness. Meat Science, 64, 341–350.  von Seth, G., & Tornberg, E. (2003b). Sensory quality and Josell, A., the incidence of PSE of pork in relation to crossbreed and RN phenotype. Meat Science, 65, 651–660. Krause, R. J., Plimpton, R. F., Ockerman, H. W., & Cahill, V. R. (1978a). Influence of tumbling and sodium tripolyphosphate on salt and nitrite distribution in porcine muscle. Journal of Food Science, 43, 190–192. Krause, R. J., Ockerman, H. W., & Cahill, V. R. (1978b). Influence of tumbling, tumbling time, trim and sodium tripolyphospate on quality and yield of cured hams. Journal of Food Science, 43, 853– 855. Lawlis, T. L., Plimpton, R. F., Ockerman, H. W., & Parrett, N. A. (1992). Electrical stimulation and tumbling affect pre-rigor cured, sectioned and formed ham roasts. Journal of Food Science, 57, 564– 568, 616. Le Roy, P., Elsen, J. M., Caritez, J. C., Talmant, A., Juin, H., Sellier, P., & Monin, G. (2000). Comparison between the three porcine RN genotypes for growth, carcass composition and meat quality traits. Genetics Selection Evolution, 32, 165–186. Le Roy, P., Naveau, J., Elsen, J. M., & Sellier, P. (1990). Evidence for a new major gene influencing meat quality in pigs. Genetical Research, Cambridge, 55, 33–40.

 Hedebro-Velander, Lindahl, G., Enf€alt, A. C., von Seth, G., Josell, A., I., Andersen, H. J., Braunschweig, M., Andersson, L., & Lundstr€ om, K. (2004). A new allele (V199I) at the PRKAG3 (RN) locus – II. Effect of colour characteristics of pork loin. Meat Science, 66, 621–627. Lundstr€ om, K., Andersson, A., & Hansson, I. (1996). Effect of the RN
gene on technological and sensory meat quality in crossbred pigs with Hampshire as terminal sire. Meat Science, 42, 145–153. Lundstr€ om, K., & Enf€alt, A. C. (1997). Rapid prediction of RN phenotype in pigs by means of meat juice. Meat Science, 45, 127–131. Lundstr€ om, K., Enf€alt, A. C., Tornberg, E., & Agerhem, H. (1998a). Sensory and technological meat quality in carriers and non-carriers of the RN
allele in Hampshire crosses and in purebred Yorkshire pigs. Meat Science, 48, 115–124. Lundstr€ om, K., Enf€alt, A. C., Hansson, I., Ess
en-Gustavsson, B., Johansson, M., Tornberg, E. (1998). Technological meat quality in carriers and non-carriers of the RN
allele in Hampshire crosses with a low or high lean meat content. In Proceedings of the 44th international congress of meat science and technology (pp. 910–911), Barcelona, Spain. Milan, D., Jeon, J. T., Looft, C., Amarger, V., Robic, A., Thelander, M., Rogel-Gaillard, C., Paul, S., Iannuccelli, N., Rask, L., Ronne, H., Lundstr€ om, K., Reinsch, N., Gellin, J., Kalm, E., Le Roy, P., Chardon, P., & Andersson, L. (2000). A mutation in PRKAG3 associated with excess glycogen content in pig skeletal muscle. Science, 288, 1248–1251. Miller, K. D., Ellis, M., McKeith, F. K., Bidner, B. S., & Meisinger, D. J. (2000). Frequency of the Rendement Napole RN
allele in a population of American Hampshire pigs. Journal of Animal Science, 78, 1811–1815. Moeller, S. J., Baas, T. J., Leeds, T. D., Emnett, R. S., & Irvin, K. M. (2003). Rendement Napole gene effects and a comparison of glycolytic potential and DNA genotyping for classification of Rendement Napole status in Hampshire-sired pigs. Journal of Animal Science, 81, 402–410. Monin, G. (1995). The effect of the RN
gene on fresh and processed pork. In K. Lundstr€ om, I. Hansson, & E. Wiklund (Eds.), Composition of meat in relation to processing, nutritional and sensory quality – From farm to fork (pp. 57–67). Utrecht: ECCEAMST. Monin, G., Brard, C., Vernin, P., & Naveau, J. (1992). Effects of the RN
gene on some traits of muscle and liver in pigs. In Proceedings of the 38th international congress of meat science and technology (pp. 391–394), Clermont-Ferrand, France. Monin, G., & Sellier, P. (1985). Pork of low technological quality with a normal rate of muscle pH fall in the immediate post-mortem period: The case of the Hampshire breed. Meat Science, 13, 49–63. M€ uller, W. D. (1991). Cooked cured products. Influence of manufacturing technology. Fleischwirtschaft, 71, 544, 546–550. Naveau, J. (1986). Contribution a lÕ
etude du d
eterminisme g
en
etique de la qualit
ede viande porcine. H
eritabilit
edu Rendement Technologique NAPOLE. Journ
es de la Recherche Porcine en France, 18, 265–276. Naveau, J., Pommeret, P., & Lechaux, P. (1985). Proposition dÕune m
ethode de mesure du rendement technologique: la ’’m
ethode Napole’’. Techni-porc, 8, 7–13. Offer, G., & Knight, P. (1988a). The structural basis of water-holding in meat. Part 1: General principles and water uptake in meat processing. In R. Lawrie (Ed.), Developments in meat science (Vol. 4, pp. 63–171). London: Elsevier Science. Offer, G., & Knight, P. (1988b). The structural basis of water-holding in meat: Part 2: Drip losses. In R. Lawrie (Ed.), Developments in meat science (Vol. 4, pp. 173–243). London: Elsevier Science. Olsson, V., Andersson, K., Hansson, I., & Lundstr€ om, K. (2003). Differences in meat quality between organically and conventionally produced pigs. Meat Science, 64, 287–297.

A. Hullberg, K. Lundstr€om / Meat Science 67 (2004) 409–419 Pietrasik, Z., & Shand, P. J. (2002). Effect of mechanical tenderisation and tumbling time on the processing characteristics and tenderness of cooked roast beef. In Proceedings of the 48th international congress of meat science and technology (pp. 876–877), Rome, Italy. Rosenvold, K., Laerke, H. N., Jensen, S. K., Karlsson, A. H., Lundstr€ om, K., & Andersen, H. J. (2001). Strategic finishing feeding as a tool in the control of pork quality. Meat Science, 59, 397–406. Schmidt, G. R. (1984). Processing effects on meat product microstructure. Food Microstructure, 3, 33–39.

419

Sch€afer, A., Rosenvold, K., Purslow, P. P., Andersen, H. J., & Henckel, P. (2002). Physiological and structural events postmortem of importance for drip loss in pork. Meat Science, 61, 355–366. Sellier, P., & Monin, G. (1994). Genetics of pig meat quality: A review. Journal of Muscle Foods, 5, 187–219. Siegel, D. G., Theno, D. M., & Schmidt, G. R. (1978). Meat massaging: The effects of salt, phosphate and massaging on presence of specific skeletal muscle proteins in the exudate of a sectioned and formed ham. Journal of Food Science, 43, 327–330.