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Benchmarking value in the pork supply chain: Processing and consumer characteristics of hams manufactured from different quality raw materials
MEAT SCIENCE Meat Science 70 (2005) 91–97 www.elsevier.com/locate/meatsci
Benchmarking value in the pork supply chain: Processing and consumer characteristics of hams manufactured from different quality raw materials R.C. Person a, D.R. McKenna a, J.W. Ellebracht a, D.B. Griffin a, F.K. McKeith b, J.A. Scanga c, K.E. Belk c, G.C. Smith c, J.W. Savell a,* a
Meat Science Section, Department of Animal Science, Texas Agricultural Experiment Station, Texas A&M University, 2471 TAMU, College Station, TX 77843-2471, USA b Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA c Department of Animal Sciences, Colorado State University, Ft. Collins, CO 80523, USA Received 16 September 2004; received in revised form 6 January 2005; accepted 6 January 2005
Abstract Impact of fresh ham quality on finished ham product characteristics was evaluated. Bone-in hams destined for spiral-sliced ham manufacturing were sorted into two pH groups before processing: pH 6 5.5 and pH P 5.6. For boneless hams, raw materials were sorted into groups with different levels of pale, soft, and exudative (PSE) product before manufacturing into sliced vacuum packaged hams: ‘‘Low PSE’’ (65% PSE muscle), ‘‘Intermediate PSE’’ (20–30% PSE muscle) or ‘‘High PSE’’ (40–60% PSE muscle). Few differences were observed between the pH 6 5.5 and pH P 5.6 groups in objective color measures and drip loss in bone-in spiral-sliced hams stored under refrigeration, however, after frozen storage, hams from the pH 6 5.5 group had lower L*- and a*-values and had much higher drip loss than those from the pH P 5.6 group. Processing yields for bone-in spiral-sliced hams were similar through cooking and chilling, however, the pH P 5.6 group had higher yields after slicing. For boneless hams, defects occurred at a greater frequency in hams formulated with a greater percentage of PSE raw materials than those with lower amounts of PSE. Differences in objective color measures and purge were minimal over the duration of storage time, but hams formulated with greater percentages of PSE raw materials were lighter in appearance and had less redness. Consumers gave lower color responses for hams formulated with ‘‘High PSE’’ amounts, but did not differentiate between hams manufactured with lower quantities of PSE muscle. However, when consumers directly compared packages of ham, there was distinct discrimination against hams manufactured with greater amounts of PSE. Purchase intent showed that consumers favored ham manufactured from fresh ham muscles containing low quantities of PSE tissue. Further research is needed to determine the optimal ratio of allowable PSE product in formulation that enables processors to maximize consumer appeal with the economic realities of sorting out PSE pork. 2005 Elsevier Ltd. All rights reserved. Keywords: Consumer evaluation; Ham; pH; Pork; PSE
1. Introduction Cannon et al. (1996) found that economic losses associated with low pork quality were estimated to be only *
Corresponding author. Tel.: +1 979 845 3935; fax: +1 979 845 9454. E-mail address: [email protected] (J.W. Savell).
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3% of the unrealized revenue lost from nonconformities in carcass quality. Today, low pork quality accounts for nearly 24% of the unrealized revenue lost from nonconformities in carcass quality, with most of those losses associated with pale, soft, and exudative (PSE) pork, and muscles containing low water-holding properties (Stetzer & McKeith, 2003). The 2003 estimate of PSE
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incidence was 15.5% (Stetzer & McKeith, 2003) compared to 10.2% reported for 1992 by Cannon et al. (1996). It is often difficult to define the extent of PSE within a muscle; in many cases, muscles will exhibit varying degrees of PSE tissue. For example, the medial portion of a ham muscle may be entirely PSE, whereas the lateral portion of that same ham muscle may appear normal. The weight of hams increased 19% compared to 1992 (Stetzer & McKeith, 2003), making the aforementioned scenario more likely to occur because as the mass of a ham increases, it becomes more difficult to chill rapidly. This is one of the phases of the project, ‘‘Benchmarking Value in the Pork Supply Chain.’’ This industryfunded research addressed key issues related to pork quality and value losses for US pork. The ham processing industry uses a majority of the ham muscles produced by the packing sector, however, little research has been conducted to evaluate the production inefficiencies, such as decreased processing yields, increased rework, and decreased consumer demand from inferior products resulting from using raw materials with poor color and water-holding properties. The objective of this study was to determine the impact of different quality raw materials on the processing characteristics of hams.
the National Pork Board (NPB, 2000). All hams were vacuum packaged, and random selections (n = 20 per group) were evaluated for objective color measures (CIE L*-, a*-, and b*-values) using a Hunter MiniScan XE (HunterLab Associates, Inc., Reston, VA) with a 2.54-cm aperature, 10 standard observer, and illuminant A. Objective color measures were recorded as the mean of three independent measures in the center of the M. semimembranosus, M. biceps femoris, and M. semitendinosus, respectively. To evaluate the effects of refrigerated and frozen storage on ham quality, vacuum packaged rump and shank portions (n = 24 per pH group) were selected randomly and shipped to the Rosenthal Meat Science and Technology Center at Texas A&M University. Upon arrival, 12 hams from each pH group were placed in a 10 C freezer for a 137-day storage period. The remaining hams were placed in a 2 C cooler. For the hams stored at 2 C, three from each pH group were selected randomly after 30-, 45-, 60- or 75-days, and objective color measures (as previously described) and purge loss data were collected. Following frozen storage, hams were allowed to thaw in a 2 C cooler for 24 days to simulate commercial practices to supply the increased seasonal demand for spiral-sliced hams during various US holidays. After thawing, objective color measures and purge loss data were collected for each ham.
2. Materials and methods
2.2. Boneless ham manufacture
2.1. Bone-in ham manufacture
Pork leg (fresh ham), insides (IMPS #402F; NAMP, 1997; USDA, 1997), containing the M. semimembranosus, M. adductor, and M. gracilis, were sorted from the end of a pork cutting line based on a visual appraisal of the amount of pale, soft, and exudative (PSE) muscle that each inside contained. This appraisal was made using the NPPC (1999) color standards as a reference to characterize the relative amount of PSE (NPPC, 1999, color score of 1 or 2) in each inside ham. Inside hams in the ‘‘Low PSE’’ group were targeted to contain 65% PSE tissue, whereas muscles in the ‘‘Intermediate PSE’’ group were targeted to range between 20% and 30% PSE, and muscles from the ‘‘High PSE’’ group were targeted to range between 40% and 60% PSE. (To validate this classification approach, 45 kg samples from each group had the PSE portions removed and weighed, and the approximate amounts were within the targeted ranges.) For each inside ham group, objective color measures (CIE L*-, a*-, and b*-values) and pH values were collected at the time of sorting using a Hunter MiniScan XE (HunterLab Associates, Inc., Reston, VA) and a handheld pH meter (pHStar, SFK Technologies, Inc, Cedar Rapids, IA). Objective color measures and pH determinations (n = 100 inside hams per group) were obtained in two locations on the medial side of selected
Fresh hams (IMPS #401; NAMP, 1997; USDA, 1997) were selected from the fabrication line of a commercial processor. The pH of the M. psoas major in the ham face was measured with a handheld pH meter (pHStar, SFK Technologies, Cedar Rapids, IA). Hams were sorted into two groups, pH 6 5.5 and pH P 5.6, and were processed into bone-in spiral-sliced hams following plant-specific commercial procedures. (Brine formulation, injection amounts, and smoking/cooking cycles were proprietary and are not reported within; however, both treatment groups were processed the same way.) Weights were collected throughout processing and were used to calculate cook shrink, chill shrink, pack-off yield (yield after spiral-slicing), and final yield (yield after spiral-slicing and rejection of product that did not meet plant-specific quality standards). After processing and slicing, hams were bisected into rump and shank portions and evaluated for the incidence of visible defects in the cut lean surface. Approximately 10 min after bisection, hams (n = 20 per group) were selected randomly to be tested for water-holding capacity using a filter-paper drip loss test developed by Kauffman, Eikelenboom, Van Der Wal, Merkus, and Zaar (1986) with standardized procedures described by
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muscles. Approximately 3000 kg of raw materials were obtained for each group, and an additional 3000 kg of commodity (unsorted) muscles were collected to serve as a control. All raw materials were shipped by refrigerated carrier to a commercial ham processing facility. After receiving at a ham manufacturing plant, inside ham muscles were removed from their containers and the purge was collected and weighed (the plantÕs process reincorporated purge into the manufacturing scheme). Muscles were injected with a curing solution, macerated, massaged, formed, and cooked using plant-specific procedures within the commercial processing facility to produce a 4 · 6 (10.2 · 15.2 cm) ham, water added product. After cooking, ham logs were chilled and stored for approximately 3 weeks before slicing. Ham logs were crust-frozen, sliced, and packaged in 454 g packages. Hams slices were evaluated for defects after slicing, which were classified as normal rework (i.e., small tears, end pieces, or other minor imperfections) or PSE rework (i.e., severe product defects associated with low functionality muscle). Ham slices were evaluated for color uniformity during packaging. Slices containing nominal variations in color were classified as normal or no defect, those containing slight contrasts in color uniformity or small pale spots were classified as having minor defects, and those exhibiting substantial contrasts in color uniformity, large pale spots or small pockets were considered to have major defects. Packages (n = 100 per group) also were evaluated for objective color measures (CIE L*-, a*-, and b*-values) using a Hunter MiniScan XE (HunterLab Associates, Inc., Reston, VA). Four locations were measured on each package and averaged to determine a mean color score for each package. Packaged, finished ham products from each group were selected randomly and shipped to the Rosenthal Meat Science and Technology Center at Texas A&M University. Upon arrival, ham packages were placed in a 2 C cooler for storage. Packages of ham (n = 17 per group) were selected after 15-, 30-, 45-, 60- or 75-days of storage, objective color measures (CIE L*-, a*-, and b*-values) were collected as previously described, and the weight of purge was measured from each package. On day 45, ham slices also were evaluated for textural differences and consumer sensory evaluations. Textural assessments (n = 200 slices per group) were measured using an Instron Universal Testing Machine equipped with an Allo–Kramer shear apparatus. Shear values are the mean of two shears on each slice and are reported as N/g. Consumer evaluations were conducted at the sensory testing facility at Texas A&M University. Participants were recruited from the faculty, students, and staff at Texas A&M University. Participants were asked to rate samples from each ham group for flavor intensity, overall like of flavor, visual appeal, and color. Participants were placed in individual panelist booths and given samples one at a time in random order. Bal-
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lots consisted of an 8-point scale for each trait evaluated (1 = extremely dislike; 8 = extremely like). In addition, purchase intent was determined by asking participants to select three packages of ham from an assortment of 12 packages. All groups of hams were represented equally, and their arrangement was randomized. Packages that participants selected and the order that they selected packages was recorded. 2.3. Statistical analysis Data were analyzed using the SAS software package (SAS Institute, Inc., Cary, NC). Frequency distributions (not statistically analyzed) were generated using the PROC Freq procedure. Analysis of variance was performed using the PROC GLM procedure with product quality group tested as the main effect. When main effects were determined to be significant (P < 0.05), least squares means were generated and separated using a pairwise t-test (pdiff option).
3. Results and discussion 3.1. Bone-in hams Processing yields for the pH 6 5.5 and pH P 5.6 groups are shown in Fig. 1. Yields were similar for both pH groups through cooking and chilling, however, the pH P 5.6 group had higher numerical yields after spiral-slicing and packaging. In addition, the pH 6 5.5 group had an additional 2% yield loss after sliced hams that did not meet plant-based quality standards were rejected. OÕNeill, Lynch, Troy, Buckley, and Kerry (2003) reported that sliceability was determined by water retention and cohesiveness, which are dependent upon protein extraction and gelation. Bowker, Wynveen, Grant, and Gerrard (2000) and Briskey and Wismer-Pederson (1961) found that economic and processing losses
Fig. 1. Processing yields for bone-in spiral sliced hams from two different pH groups at various aspects of the production cycle.
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associated with PSE products are a result of the low protein functionality in those products. Initial objective color measures showed that hams from the pH 6 5.5 group had lower (P < 0.05) a*-values than hams from the pH P 5.6 group (11.48 vs. 12.31, respectively). There were no differences between pH groups for L*- and b*-values. Hams from the pH 6 5.5 group had higher (P < 0.05) drip losses than hams from the pH P 5.6 group (5.3% vs. 4.0%, respectively). Kauffman, Wachholz, Henderson, and Lochner (1978) reported 1% greater shrink in PSE bone-in fresh hams compared to normal bone-in fresh hams during shipping, however, little research has been conducted on the effects of PSE raw materials on quality parameters of bone-in hams that have been cured and processed. Because there were no pH group · storage day interactions, objective color measures and drip losses were averaged across storage days for each pH group (Table 1). The pH 6 5.5 group had higher (P < 0.05) L*-values and lower (P < 0.05) a*-values indicating that those hams were paler and less red than those from the pH P 5.6 group. This was expected because lower pH pork products generally have been characterized as paler in color than higher pH pork products. The lack of significant differences in drip loss between pH groups was somewhat unexpected, but may have been impacted by variables not addressed in this study. There were similar findings between pH groups for objective color measures for hams that were frozen and thawed (Table 2) compared to those that were evaluated after refrigerated storage. However, percentage drip loss was much higher (P < 0.05) in the pH 6 5.5 group than in the pH P 5.6 group. If spiral-sliced hams
are to be frozen and stored to meet seasonal demands, pH of the fresh ham may be a factor to be considered if drip or purge loss is a concern. 3.2. Boneless hams Least squares means for pH values and objective color measures for raw M. semimembranosus muscles at the time of sorting are characterized in Table 3. Sorting was effective in stratifying quality groups as the group containing the lowest amount of PSE had the highest pH and the group containing the most PSE muscle had the lowest pH values (P < 0.05). Furthermore, pH differences between groups were incremental, with approximately 0.2 units separating each group. Kauffman et al. (1978) found that hams classified as ‘‘PSE’’ had a pH (as measured in M. gluteus medius) of 5.5, whereas ‘‘normal’’ hams had a pH of 5.9, and dark, firm, and dry hams had a pH of 6.3. Differences in objective color measures between raw material quality groups were as expected. The ‘‘Low PSE’’ group had the lowest L*-values and b*-values and the highest a*-values, whereas the ‘‘High PSE’’ group had the highest L*-values and b*-values and the lowest a*-values (P < 0.05). Color and pH values for the control group were situated between the values recorded for the ‘‘Low PSE’’ group and the ‘‘Intermediate PSE’’ group. We estimated that the incidence of PSE
Table 3 Least squares means for color and pH values for M. semimembranosus sorted into quality groups Parameter
Table 1 Least squares means of objective color measures and drip loss for bone-in hams across all storage days Treatment group
L*
a*
b*
Drip loss (%)
pH P 5.6 pH 6 5.5 SEMa
63.42b 65.42a 0.460
12.25a 11.44b 0.174
10.57 10.51 0.155
0.99 1.35 0.169
a*
b*
Drip loss (%)
pH P 5.6 pH 6 5.5 SEMa
62.89a 67.88b 0.71
12.17a 10.65b 0.29
10.95 10.79 0.15
4.2a 6.9b 0.44
Least squares means within a column lacking a common letter (a–b) are different (P < 0.05). a SEM is the standard error of the least squares means.
Inside
Outside
Mean
55.74b 53.38c 56.43b 60.51a 0.45
57.47c 54.53d 59.83b 64.20a 0.36
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
59.19c 55.68d 63.23b 67.89a 0.44
a*
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
6.95b 8.22a 7.30b 5.99c 0.17
b*
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
11.05c 9.45d 12.63b 14.54a 0.17
10.47b 8.95c 10.34b 12.21a 0.16
10.76c 9.20d 11.49b 13.38a 0.14
pH
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
6.02b 6.23a 5.87c 5.64d 0.02
5.94b 6.05a 5.77c 5.60d 0.02
5.98b 6.14a 5.82c 5.62d 0.02
Table 2 Least squares means for objective color measures and drip loss for bone-in spiral sliced hams after 137-days of frozen storage and a 3week thaw period L*
Location
L*
Least squares means within a column lacking a common letter (a–b) are different (P < 0.05). a SEM is the standard error of the least squares means.
Group
Group
7.73b 8.55a 8.09ab 6.44c 0.18
7.34b 8.39a 7.70b 6.22c 0.14
Least squares means in a column within a parameter and lacking a common letter (a–d) are different (P < 0.05). a SEM is the standard error of the least squares means.
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was less than 5% in the ‘‘Low PSE’’ group and between 20% and 30% in ‘‘Intermediate PSE’’ group. Because color and pH data indicate that raw materials in the control group fit between those groups, we expect that the control group contained 10–15% PSE muscle, which is similar to incidence rates reported by Stetzer and McKeith (2003), Cannon et al. (1996), and Kauffman, Cassens, Scherer, and Meeker (1992). No quality group · storage time interaction was observed so means for objective color measures and purge loss were pooled across all storage times (Table 4). Stratification of L*- and a*-values for boneless hams manufactured from different quality groups was identical to stratification of L*- and a*-values observed in raw materials (Table 3). Hams manufactured from the control group had the lowest (P < 0.05) b*-values, which was unexpected because raw material data indicated that the ‘‘Low PSE’’ group had the lowest b*-values. Hams manufactured from the ‘‘Low PSE’’ group had the lowest (P < 0.05) purge loss, followed by hams from the control group. No difference in purge loss was observed between hams manufactured from the ‘‘Intermediate PSE’’ group and the ‘‘High PSE’’ group. OÕNeill et al. (2003) reported that drip loss in cooked hams manufactured from PSE pork was four times greater than hams manufactured from normal pork. Differences observed in this study were not as severe as those described by OÕNeill et al. (2003), however, this may be because drip and purge loss were measured using different methods. The discrepancy in purge loss differences between hams manufactured from the different quality groups may be explained partially by the extent of purge loss in the raw materials before processing (data not shown in tabular form). Control and ‘‘Low PSE’’ raw materials possessed the ability to hold water more effectively as they had 0.7% and 0.6% purge loss, respectively, in storage before processing. In contrast, raw materials from the ‘‘Intermediate PSE’’ group had a 1.0% purge loss, and raw materials from the ‘‘High PSE’’ group had 2.6% purge loss indicating much lower water-holding capacity. This was expected as Offer (1991) previously described lower water-holding capacities in muscle containing greater denaturation. After processing, it was not ex-
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pected that hams manufactured from the ‘‘Intermediate PSE’’ and ‘‘High PSE’’ groups would have similar purge loss percentages. We expected the ‘‘High PSE’’ group would have the greatest purge loss because greater quantities of PSE muscle should have less functional protein and lower water-holding capacities. Boneless hams were sliced, sorted into 454 g samples, and vacuum-packaged. Before packaging, ham groups were assessed for quality defects that would be considered ‘‘normal rework’’ (i.e., ends and pieces, small pockets, etc.) or ‘‘PSE-outs’’ (i.e., severe holes in the product caused by a lack of functional protein). Boneless hams manufactured from the ‘‘Low PSE’’ group had the lowest numerical incidence of quality defects and lowest numerical total yield loss (Fig. 2). Incidence rates for ‘‘PSE-outs’’ and total yield loss were three times greater in control product than were observed in hams manufactured from the ‘‘Low PSE’’ group. Incidence rates for ‘‘PSE-outs’’ in the ‘‘Intermediate PSE’’ and ÔHigh PSE’’ groups were 5–6 times greater than those observed in the ‘‘Low PSE’’ group. Moreover, total yield losses observed in the ‘‘Intermediate PSE’’ and ‘‘High PSE’’ groups were four to five times greater than the yield losses observed in the ‘‘Low PSE’’ group. OÕNeill et al. (2003) reported the importance of water retention and cohesiveness in slicing. As greater percentages of PSE in the raw materials were incorporated into the ham formulations, water retention and cohesiveness would be reduced because of the incorporation of less functional protein. Surprisingly, incidence rates for ‘‘normal rework,’’ and ‘‘PSE-outs,’’ and thus total yield losses were the highest numerically in hams manufactured from the ‘‘Intermediate PSE’’ group. We expected incremental increases in slicing defects as the percentage of PSE pork included in the hams increased; clearly this was not the case. Raw materials in the ‘‘Intermediate PSE’’ group may have been the most heterogeneous and therefore presented the greatest challenge of merging ‘‘functional protein’’ with ‘‘non-functional’’ protein (i.e., PSE muscle).
Table 4 Least squares means of objective color measures and purge for packages of boneless ham across all storage days Treatment group
L*
a*
b*
Purge (%)
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
64.29c 63.33d 65.40b 66.17a 0.179
12.35b 12.78a 12.00c 11.77d 0.785
9.46c 9.68b 9.67b 9.84a 0.038
1.38b 1.19c 1.82a 1.78a 0.056
Least squares means within a column lacking a common letter (a–d) are different (P < 0.05). a SEM is the standard error of the least squares means.
Fig. 2. Frequency of slicing defects for boneless hams manufactured from quality groups containing different levels of PSE tissue.
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After packaging, finished hams (after ‘‘normal rework’’ and ‘‘PSE-outs’’ were sorted out) were assessed for minor and major appearance defects (Fig. 3). Generally, percentage of defects increased incrementally with increasing levels of PSE product in the raw materials. Hams manufactured from the ‘‘Low-PSE’’ group numerically had the highest percentage of packages with no defects and virtually no packages with major defects. In contrast, only half of all packages containing ham manufactured from the ‘‘High PSE’’ group had no defects, whereas 43.1% contained a minor defect. Demographic data provided by consumers indicated that nearly 64% of participants were between the ages of 20 and 39, and approximately 45% were male and 55% were female. Consumer evaluations of finished ham products are displayed in Table 5. Consumers indicated no preference for ‘‘flavor’’ or ‘‘overall like’’ of ham from any of the quality groups. Consumers gave the lowest (P < 0.05) color ratings for ham manufactured from the ‘‘High PSE’’ group, but gave similar (P > 0.05) color ratings for hams manufactured from the other quality groups. Ratings for visual appeal were similar to ratings for color as consumers gave the lowest (P < 0.05) ratings for ham from the ‘‘High PSE’’ group, but did not differentiate the ham manufactured from the other quality groups.
Purchase intent for packages of ham manufactured from the different quality groups showed even greater consumer discrimination against hams manufactured from different quality groups than color or visual appeal responses (Fig. 4). Overall selection showed that nearly 60% of consumer selections were packages of ham manufactured from the ‘‘Low PSE’’ quality group with 64% of consumers making one of those packages their first selection. Packages of ham manufactured from the ‘‘Intermediate PSE’’ quality group had the second most frequent selection, whereas packages of ham manufactured from the control group and the ‘‘High PSE’’ quality group were selected the least frequently. We expected selection frequencies for packages of ham from the control group and ‘‘Intermediate PSE’’ group to have similar selection responses, however, this was not the case. It is unclear why consumers discriminated against ham packages from the control group. Consumer data showed that color and visual appeal responses for ham from control, ‘‘Low PSE,’’ and ‘‘High PSE’’ products were similar. It is interesting to note that when consumers were asked to make independent ratings of hams, they gave responses that indicated very little difference in the color and visual properties of the hams manufactured from the various quality groups. Nonetheless, when consum-
Fig. 3. Appearance defects for packages of ham from boneless hams manufactured from quality groups containing different levels of PSE tissue.
Fig. 4. Frequency distributions for consumer purchase intent for packages of ham from boneless hams manufactured from quality groups containing different levels of PSE tissue.
Table 5 Least squares means for consumer responses for visual and palatability characteristics and Allo–Kramer shear values for ham from different quality groups Group
Sensory trait
Allo–Kramer shear (N/g)
Visual appeal
Color
Flavor
Overall like
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
5.23a 5.48a 5.23a 4.63b 0.13
5.08a 5.40a 5.20a 4.40b 0.13
5.45 5.41 5.44 5.37 0.13
5.36 5.41 5.47 5.35 0.13
Least squares means within a column lacking a common letter (a–c) are different (P < 0.05). a SEM is the standard error of the least squares means.
29.7c 32.5ab 32.2b 33.3a 0.29
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ers were in a situation that they could directly compare packages of ham (i.e., similar to a retail environment), there was distinct discrimination against hams manufactured with greater amounts of PSE in the raw materials. Whether or not consumers would be willing to spend more for hams manufactured with low quantities of PSE will require further research.
4. Conclusions Sorting raw pork materials according to quality parameters (i.e., pH and PSE) impacts the processing yields and consumer appeal of products manufactured from those raw materials. Particular emphasis should be placed on selecting hams with pH values of 5.6 or greater for bone-in processing because their sliceability and water-holding properties will better withstand deterioration often associated with these products when they are frozen and then thawed. For boneless ham manufacturing, processing yields and defects were minimized when muscles containing high levels of PSE tissue were eliminated. Further research is needed to determine the optimal ratio of allowable PSE product in formulation that enables processors to maximize consumer appeal with the economic realities of sorting out PSE pork.
Acknowledgements Technical article from the Texas Agricultural Experiment Station. This study was supported, in part, by the American Meat Science Association, Savoy, IL on behalf of the National Pork Board and a number of pork genetic and processing companies.
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Benchmarking value in the pork supply chain: Processing and consumer characteristics of hams manufactured from different quality raw materials R.C. Person a, D.R. McKenna a, J.W. Ellebracht a, D.B. Griffin a, F.K. McKeith b, J.A. Scanga c, K.E. Belk c, G.C. Smith c, J.W. Savell a,* a
Meat Science Section, Department of Animal Science, Texas Agricultural Experiment Station, Texas A&M University, 2471 TAMU, College Station, TX 77843-2471, USA b Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA c Department of Animal Sciences, Colorado State University, Ft. Collins, CO 80523, USA Received 16 September 2004; received in revised form 6 January 2005; accepted 6 January 2005
Abstract Impact of fresh ham quality on finished ham product characteristics was evaluated. Bone-in hams destined for spiral-sliced ham manufacturing were sorted into two pH groups before processing: pH 6 5.5 and pH P 5.6. For boneless hams, raw materials were sorted into groups with different levels of pale, soft, and exudative (PSE) product before manufacturing into sliced vacuum packaged hams: ‘‘Low PSE’’ (65% PSE muscle), ‘‘Intermediate PSE’’ (20–30% PSE muscle) or ‘‘High PSE’’ (40–60% PSE muscle). Few differences were observed between the pH 6 5.5 and pH P 5.6 groups in objective color measures and drip loss in bone-in spiral-sliced hams stored under refrigeration, however, after frozen storage, hams from the pH 6 5.5 group had lower L*- and a*-values and had much higher drip loss than those from the pH P 5.6 group. Processing yields for bone-in spiral-sliced hams were similar through cooking and chilling, however, the pH P 5.6 group had higher yields after slicing. For boneless hams, defects occurred at a greater frequency in hams formulated with a greater percentage of PSE raw materials than those with lower amounts of PSE. Differences in objective color measures and purge were minimal over the duration of storage time, but hams formulated with greater percentages of PSE raw materials were lighter in appearance and had less redness. Consumers gave lower color responses for hams formulated with ‘‘High PSE’’ amounts, but did not differentiate between hams manufactured with lower quantities of PSE muscle. However, when consumers directly compared packages of ham, there was distinct discrimination against hams manufactured with greater amounts of PSE. Purchase intent showed that consumers favored ham manufactured from fresh ham muscles containing low quantities of PSE tissue. Further research is needed to determine the optimal ratio of allowable PSE product in formulation that enables processors to maximize consumer appeal with the economic realities of sorting out PSE pork. 2005 Elsevier Ltd. All rights reserved. Keywords: Consumer evaluation; Ham; pH; Pork; PSE
1. Introduction Cannon et al. (1996) found that economic losses associated with low pork quality were estimated to be only *
Corresponding author. Tel.: +1 979 845 3935; fax: +1 979 845 9454. E-mail address: [email protected] (J.W. Savell).
0309-1740/$ - see front matter 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2005.01.001
3% of the unrealized revenue lost from nonconformities in carcass quality. Today, low pork quality accounts for nearly 24% of the unrealized revenue lost from nonconformities in carcass quality, with most of those losses associated with pale, soft, and exudative (PSE) pork, and muscles containing low water-holding properties (Stetzer & McKeith, 2003). The 2003 estimate of PSE
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incidence was 15.5% (Stetzer & McKeith, 2003) compared to 10.2% reported for 1992 by Cannon et al. (1996). It is often difficult to define the extent of PSE within a muscle; in many cases, muscles will exhibit varying degrees of PSE tissue. For example, the medial portion of a ham muscle may be entirely PSE, whereas the lateral portion of that same ham muscle may appear normal. The weight of hams increased 19% compared to 1992 (Stetzer & McKeith, 2003), making the aforementioned scenario more likely to occur because as the mass of a ham increases, it becomes more difficult to chill rapidly. This is one of the phases of the project, ‘‘Benchmarking Value in the Pork Supply Chain.’’ This industryfunded research addressed key issues related to pork quality and value losses for US pork. The ham processing industry uses a majority of the ham muscles produced by the packing sector, however, little research has been conducted to evaluate the production inefficiencies, such as decreased processing yields, increased rework, and decreased consumer demand from inferior products resulting from using raw materials with poor color and water-holding properties. The objective of this study was to determine the impact of different quality raw materials on the processing characteristics of hams.
the National Pork Board (NPB, 2000). All hams were vacuum packaged, and random selections (n = 20 per group) were evaluated for objective color measures (CIE L*-, a*-, and b*-values) using a Hunter MiniScan XE (HunterLab Associates, Inc., Reston, VA) with a 2.54-cm aperature, 10 standard observer, and illuminant A. Objective color measures were recorded as the mean of three independent measures in the center of the M. semimembranosus, M. biceps femoris, and M. semitendinosus, respectively. To evaluate the effects of refrigerated and frozen storage on ham quality, vacuum packaged rump and shank portions (n = 24 per pH group) were selected randomly and shipped to the Rosenthal Meat Science and Technology Center at Texas A&M University. Upon arrival, 12 hams from each pH group were placed in a 10 C freezer for a 137-day storage period. The remaining hams were placed in a 2 C cooler. For the hams stored at 2 C, three from each pH group were selected randomly after 30-, 45-, 60- or 75-days, and objective color measures (as previously described) and purge loss data were collected. Following frozen storage, hams were allowed to thaw in a 2 C cooler for 24 days to simulate commercial practices to supply the increased seasonal demand for spiral-sliced hams during various US holidays. After thawing, objective color measures and purge loss data were collected for each ham.
2. Materials and methods
2.2. Boneless ham manufacture
2.1. Bone-in ham manufacture
Pork leg (fresh ham), insides (IMPS #402F; NAMP, 1997; USDA, 1997), containing the M. semimembranosus, M. adductor, and M. gracilis, were sorted from the end of a pork cutting line based on a visual appraisal of the amount of pale, soft, and exudative (PSE) muscle that each inside contained. This appraisal was made using the NPPC (1999) color standards as a reference to characterize the relative amount of PSE (NPPC, 1999, color score of 1 or 2) in each inside ham. Inside hams in the ‘‘Low PSE’’ group were targeted to contain 65% PSE tissue, whereas muscles in the ‘‘Intermediate PSE’’ group were targeted to range between 20% and 30% PSE, and muscles from the ‘‘High PSE’’ group were targeted to range between 40% and 60% PSE. (To validate this classification approach, 45 kg samples from each group had the PSE portions removed and weighed, and the approximate amounts were within the targeted ranges.) For each inside ham group, objective color measures (CIE L*-, a*-, and b*-values) and pH values were collected at the time of sorting using a Hunter MiniScan XE (HunterLab Associates, Inc., Reston, VA) and a handheld pH meter (pHStar, SFK Technologies, Inc, Cedar Rapids, IA). Objective color measures and pH determinations (n = 100 inside hams per group) were obtained in two locations on the medial side of selected
Fresh hams (IMPS #401; NAMP, 1997; USDA, 1997) were selected from the fabrication line of a commercial processor. The pH of the M. psoas major in the ham face was measured with a handheld pH meter (pHStar, SFK Technologies, Cedar Rapids, IA). Hams were sorted into two groups, pH 6 5.5 and pH P 5.6, and were processed into bone-in spiral-sliced hams following plant-specific commercial procedures. (Brine formulation, injection amounts, and smoking/cooking cycles were proprietary and are not reported within; however, both treatment groups were processed the same way.) Weights were collected throughout processing and were used to calculate cook shrink, chill shrink, pack-off yield (yield after spiral-slicing), and final yield (yield after spiral-slicing and rejection of product that did not meet plant-specific quality standards). After processing and slicing, hams were bisected into rump and shank portions and evaluated for the incidence of visible defects in the cut lean surface. Approximately 10 min after bisection, hams (n = 20 per group) were selected randomly to be tested for water-holding capacity using a filter-paper drip loss test developed by Kauffman, Eikelenboom, Van Der Wal, Merkus, and Zaar (1986) with standardized procedures described by
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muscles. Approximately 3000 kg of raw materials were obtained for each group, and an additional 3000 kg of commodity (unsorted) muscles were collected to serve as a control. All raw materials were shipped by refrigerated carrier to a commercial ham processing facility. After receiving at a ham manufacturing plant, inside ham muscles were removed from their containers and the purge was collected and weighed (the plantÕs process reincorporated purge into the manufacturing scheme). Muscles were injected with a curing solution, macerated, massaged, formed, and cooked using plant-specific procedures within the commercial processing facility to produce a 4 · 6 (10.2 · 15.2 cm) ham, water added product. After cooking, ham logs were chilled and stored for approximately 3 weeks before slicing. Ham logs were crust-frozen, sliced, and packaged in 454 g packages. Hams slices were evaluated for defects after slicing, which were classified as normal rework (i.e., small tears, end pieces, or other minor imperfections) or PSE rework (i.e., severe product defects associated with low functionality muscle). Ham slices were evaluated for color uniformity during packaging. Slices containing nominal variations in color were classified as normal or no defect, those containing slight contrasts in color uniformity or small pale spots were classified as having minor defects, and those exhibiting substantial contrasts in color uniformity, large pale spots or small pockets were considered to have major defects. Packages (n = 100 per group) also were evaluated for objective color measures (CIE L*-, a*-, and b*-values) using a Hunter MiniScan XE (HunterLab Associates, Inc., Reston, VA). Four locations were measured on each package and averaged to determine a mean color score for each package. Packaged, finished ham products from each group were selected randomly and shipped to the Rosenthal Meat Science and Technology Center at Texas A&M University. Upon arrival, ham packages were placed in a 2 C cooler for storage. Packages of ham (n = 17 per group) were selected after 15-, 30-, 45-, 60- or 75-days of storage, objective color measures (CIE L*-, a*-, and b*-values) were collected as previously described, and the weight of purge was measured from each package. On day 45, ham slices also were evaluated for textural differences and consumer sensory evaluations. Textural assessments (n = 200 slices per group) were measured using an Instron Universal Testing Machine equipped with an Allo–Kramer shear apparatus. Shear values are the mean of two shears on each slice and are reported as N/g. Consumer evaluations were conducted at the sensory testing facility at Texas A&M University. Participants were recruited from the faculty, students, and staff at Texas A&M University. Participants were asked to rate samples from each ham group for flavor intensity, overall like of flavor, visual appeal, and color. Participants were placed in individual panelist booths and given samples one at a time in random order. Bal-
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lots consisted of an 8-point scale for each trait evaluated (1 = extremely dislike; 8 = extremely like). In addition, purchase intent was determined by asking participants to select three packages of ham from an assortment of 12 packages. All groups of hams were represented equally, and their arrangement was randomized. Packages that participants selected and the order that they selected packages was recorded. 2.3. Statistical analysis Data were analyzed using the SAS software package (SAS Institute, Inc., Cary, NC). Frequency distributions (not statistically analyzed) were generated using the PROC Freq procedure. Analysis of variance was performed using the PROC GLM procedure with product quality group tested as the main effect. When main effects were determined to be significant (P < 0.05), least squares means were generated and separated using a pairwise t-test (pdiff option).
3. Results and discussion 3.1. Bone-in hams Processing yields for the pH 6 5.5 and pH P 5.6 groups are shown in Fig. 1. Yields were similar for both pH groups through cooking and chilling, however, the pH P 5.6 group had higher numerical yields after spiral-slicing and packaging. In addition, the pH 6 5.5 group had an additional 2% yield loss after sliced hams that did not meet plant-based quality standards were rejected. OÕNeill, Lynch, Troy, Buckley, and Kerry (2003) reported that sliceability was determined by water retention and cohesiveness, which are dependent upon protein extraction and gelation. Bowker, Wynveen, Grant, and Gerrard (2000) and Briskey and Wismer-Pederson (1961) found that economic and processing losses
Fig. 1. Processing yields for bone-in spiral sliced hams from two different pH groups at various aspects of the production cycle.
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associated with PSE products are a result of the low protein functionality in those products. Initial objective color measures showed that hams from the pH 6 5.5 group had lower (P < 0.05) a*-values than hams from the pH P 5.6 group (11.48 vs. 12.31, respectively). There were no differences between pH groups for L*- and b*-values. Hams from the pH 6 5.5 group had higher (P < 0.05) drip losses than hams from the pH P 5.6 group (5.3% vs. 4.0%, respectively). Kauffman, Wachholz, Henderson, and Lochner (1978) reported 1% greater shrink in PSE bone-in fresh hams compared to normal bone-in fresh hams during shipping, however, little research has been conducted on the effects of PSE raw materials on quality parameters of bone-in hams that have been cured and processed. Because there were no pH group · storage day interactions, objective color measures and drip losses were averaged across storage days for each pH group (Table 1). The pH 6 5.5 group had higher (P < 0.05) L*-values and lower (P < 0.05) a*-values indicating that those hams were paler and less red than those from the pH P 5.6 group. This was expected because lower pH pork products generally have been characterized as paler in color than higher pH pork products. The lack of significant differences in drip loss between pH groups was somewhat unexpected, but may have been impacted by variables not addressed in this study. There were similar findings between pH groups for objective color measures for hams that were frozen and thawed (Table 2) compared to those that were evaluated after refrigerated storage. However, percentage drip loss was much higher (P < 0.05) in the pH 6 5.5 group than in the pH P 5.6 group. If spiral-sliced hams
are to be frozen and stored to meet seasonal demands, pH of the fresh ham may be a factor to be considered if drip or purge loss is a concern. 3.2. Boneless hams Least squares means for pH values and objective color measures for raw M. semimembranosus muscles at the time of sorting are characterized in Table 3. Sorting was effective in stratifying quality groups as the group containing the lowest amount of PSE had the highest pH and the group containing the most PSE muscle had the lowest pH values (P < 0.05). Furthermore, pH differences between groups were incremental, with approximately 0.2 units separating each group. Kauffman et al. (1978) found that hams classified as ‘‘PSE’’ had a pH (as measured in M. gluteus medius) of 5.5, whereas ‘‘normal’’ hams had a pH of 5.9, and dark, firm, and dry hams had a pH of 6.3. Differences in objective color measures between raw material quality groups were as expected. The ‘‘Low PSE’’ group had the lowest L*-values and b*-values and the highest a*-values, whereas the ‘‘High PSE’’ group had the highest L*-values and b*-values and the lowest a*-values (P < 0.05). Color and pH values for the control group were situated between the values recorded for the ‘‘Low PSE’’ group and the ‘‘Intermediate PSE’’ group. We estimated that the incidence of PSE
Table 3 Least squares means for color and pH values for M. semimembranosus sorted into quality groups Parameter
Table 1 Least squares means of objective color measures and drip loss for bone-in hams across all storage days Treatment group
L*
a*
b*
Drip loss (%)
pH P 5.6 pH 6 5.5 SEMa
63.42b 65.42a 0.460
12.25a 11.44b 0.174
10.57 10.51 0.155
0.99 1.35 0.169
a*
b*
Drip loss (%)
pH P 5.6 pH 6 5.5 SEMa
62.89a 67.88b 0.71
12.17a 10.65b 0.29
10.95 10.79 0.15
4.2a 6.9b 0.44
Least squares means within a column lacking a common letter (a–b) are different (P < 0.05). a SEM is the standard error of the least squares means.
Inside
Outside
Mean
55.74b 53.38c 56.43b 60.51a 0.45
57.47c 54.53d 59.83b 64.20a 0.36
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
59.19c 55.68d 63.23b 67.89a 0.44
a*
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
6.95b 8.22a 7.30b 5.99c 0.17
b*
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
11.05c 9.45d 12.63b 14.54a 0.17
10.47b 8.95c 10.34b 12.21a 0.16
10.76c 9.20d 11.49b 13.38a 0.14
pH
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
6.02b 6.23a 5.87c 5.64d 0.02
5.94b 6.05a 5.77c 5.60d 0.02
5.98b 6.14a 5.82c 5.62d 0.02
Table 2 Least squares means for objective color measures and drip loss for bone-in spiral sliced hams after 137-days of frozen storage and a 3week thaw period L*
Location
L*
Least squares means within a column lacking a common letter (a–b) are different (P < 0.05). a SEM is the standard error of the least squares means.
Group
Group
7.73b 8.55a 8.09ab 6.44c 0.18
7.34b 8.39a 7.70b 6.22c 0.14
Least squares means in a column within a parameter and lacking a common letter (a–d) are different (P < 0.05). a SEM is the standard error of the least squares means.
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was less than 5% in the ‘‘Low PSE’’ group and between 20% and 30% in ‘‘Intermediate PSE’’ group. Because color and pH data indicate that raw materials in the control group fit between those groups, we expect that the control group contained 10–15% PSE muscle, which is similar to incidence rates reported by Stetzer and McKeith (2003), Cannon et al. (1996), and Kauffman, Cassens, Scherer, and Meeker (1992). No quality group · storage time interaction was observed so means for objective color measures and purge loss were pooled across all storage times (Table 4). Stratification of L*- and a*-values for boneless hams manufactured from different quality groups was identical to stratification of L*- and a*-values observed in raw materials (Table 3). Hams manufactured from the control group had the lowest (P < 0.05) b*-values, which was unexpected because raw material data indicated that the ‘‘Low PSE’’ group had the lowest b*-values. Hams manufactured from the ‘‘Low PSE’’ group had the lowest (P < 0.05) purge loss, followed by hams from the control group. No difference in purge loss was observed between hams manufactured from the ‘‘Intermediate PSE’’ group and the ‘‘High PSE’’ group. OÕNeill et al. (2003) reported that drip loss in cooked hams manufactured from PSE pork was four times greater than hams manufactured from normal pork. Differences observed in this study were not as severe as those described by OÕNeill et al. (2003), however, this may be because drip and purge loss were measured using different methods. The discrepancy in purge loss differences between hams manufactured from the different quality groups may be explained partially by the extent of purge loss in the raw materials before processing (data not shown in tabular form). Control and ‘‘Low PSE’’ raw materials possessed the ability to hold water more effectively as they had 0.7% and 0.6% purge loss, respectively, in storage before processing. In contrast, raw materials from the ‘‘Intermediate PSE’’ group had a 1.0% purge loss, and raw materials from the ‘‘High PSE’’ group had 2.6% purge loss indicating much lower water-holding capacity. This was expected as Offer (1991) previously described lower water-holding capacities in muscle containing greater denaturation. After processing, it was not ex-
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pected that hams manufactured from the ‘‘Intermediate PSE’’ and ‘‘High PSE’’ groups would have similar purge loss percentages. We expected the ‘‘High PSE’’ group would have the greatest purge loss because greater quantities of PSE muscle should have less functional protein and lower water-holding capacities. Boneless hams were sliced, sorted into 454 g samples, and vacuum-packaged. Before packaging, ham groups were assessed for quality defects that would be considered ‘‘normal rework’’ (i.e., ends and pieces, small pockets, etc.) or ‘‘PSE-outs’’ (i.e., severe holes in the product caused by a lack of functional protein). Boneless hams manufactured from the ‘‘Low PSE’’ group had the lowest numerical incidence of quality defects and lowest numerical total yield loss (Fig. 2). Incidence rates for ‘‘PSE-outs’’ and total yield loss were three times greater in control product than were observed in hams manufactured from the ‘‘Low PSE’’ group. Incidence rates for ‘‘PSE-outs’’ in the ‘‘Intermediate PSE’’ and ÔHigh PSE’’ groups were 5–6 times greater than those observed in the ‘‘Low PSE’’ group. Moreover, total yield losses observed in the ‘‘Intermediate PSE’’ and ‘‘High PSE’’ groups were four to five times greater than the yield losses observed in the ‘‘Low PSE’’ group. OÕNeill et al. (2003) reported the importance of water retention and cohesiveness in slicing. As greater percentages of PSE in the raw materials were incorporated into the ham formulations, water retention and cohesiveness would be reduced because of the incorporation of less functional protein. Surprisingly, incidence rates for ‘‘normal rework,’’ and ‘‘PSE-outs,’’ and thus total yield losses were the highest numerically in hams manufactured from the ‘‘Intermediate PSE’’ group. We expected incremental increases in slicing defects as the percentage of PSE pork included in the hams increased; clearly this was not the case. Raw materials in the ‘‘Intermediate PSE’’ group may have been the most heterogeneous and therefore presented the greatest challenge of merging ‘‘functional protein’’ with ‘‘non-functional’’ protein (i.e., PSE muscle).
Table 4 Least squares means of objective color measures and purge for packages of boneless ham across all storage days Treatment group
L*
a*
b*
Purge (%)
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
64.29c 63.33d 65.40b 66.17a 0.179
12.35b 12.78a 12.00c 11.77d 0.785
9.46c 9.68b 9.67b 9.84a 0.038
1.38b 1.19c 1.82a 1.78a 0.056
Least squares means within a column lacking a common letter (a–d) are different (P < 0.05). a SEM is the standard error of the least squares means.
Fig. 2. Frequency of slicing defects for boneless hams manufactured from quality groups containing different levels of PSE tissue.
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After packaging, finished hams (after ‘‘normal rework’’ and ‘‘PSE-outs’’ were sorted out) were assessed for minor and major appearance defects (Fig. 3). Generally, percentage of defects increased incrementally with increasing levels of PSE product in the raw materials. Hams manufactured from the ‘‘Low-PSE’’ group numerically had the highest percentage of packages with no defects and virtually no packages with major defects. In contrast, only half of all packages containing ham manufactured from the ‘‘High PSE’’ group had no defects, whereas 43.1% contained a minor defect. Demographic data provided by consumers indicated that nearly 64% of participants were between the ages of 20 and 39, and approximately 45% were male and 55% were female. Consumer evaluations of finished ham products are displayed in Table 5. Consumers indicated no preference for ‘‘flavor’’ or ‘‘overall like’’ of ham from any of the quality groups. Consumers gave the lowest (P < 0.05) color ratings for ham manufactured from the ‘‘High PSE’’ group, but gave similar (P > 0.05) color ratings for hams manufactured from the other quality groups. Ratings for visual appeal were similar to ratings for color as consumers gave the lowest (P < 0.05) ratings for ham from the ‘‘High PSE’’ group, but did not differentiate the ham manufactured from the other quality groups.
Purchase intent for packages of ham manufactured from the different quality groups showed even greater consumer discrimination against hams manufactured from different quality groups than color or visual appeal responses (Fig. 4). Overall selection showed that nearly 60% of consumer selections were packages of ham manufactured from the ‘‘Low PSE’’ quality group with 64% of consumers making one of those packages their first selection. Packages of ham manufactured from the ‘‘Intermediate PSE’’ quality group had the second most frequent selection, whereas packages of ham manufactured from the control group and the ‘‘High PSE’’ quality group were selected the least frequently. We expected selection frequencies for packages of ham from the control group and ‘‘Intermediate PSE’’ group to have similar selection responses, however, this was not the case. It is unclear why consumers discriminated against ham packages from the control group. Consumer data showed that color and visual appeal responses for ham from control, ‘‘Low PSE,’’ and ‘‘High PSE’’ products were similar. It is interesting to note that when consumers were asked to make independent ratings of hams, they gave responses that indicated very little difference in the color and visual properties of the hams manufactured from the various quality groups. Nonetheless, when consum-
Fig. 3. Appearance defects for packages of ham from boneless hams manufactured from quality groups containing different levels of PSE tissue.
Fig. 4. Frequency distributions for consumer purchase intent for packages of ham from boneless hams manufactured from quality groups containing different levels of PSE tissue.
Table 5 Least squares means for consumer responses for visual and palatability characteristics and Allo–Kramer shear values for ham from different quality groups Group
Sensory trait
Allo–Kramer shear (N/g)
Visual appeal
Color
Flavor
Overall like
Control ‘‘Low PSE’’ ‘‘Intermediate PSE’’ ‘‘High PSE’’ SEMa
5.23a 5.48a 5.23a 4.63b 0.13
5.08a 5.40a 5.20a 4.40b 0.13
5.45 5.41 5.44 5.37 0.13
5.36 5.41 5.47 5.35 0.13
Least squares means within a column lacking a common letter (a–c) are different (P < 0.05). a SEM is the standard error of the least squares means.
29.7c 32.5ab 32.2b 33.3a 0.29
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ers were in a situation that they could directly compare packages of ham (i.e., similar to a retail environment), there was distinct discrimination against hams manufactured with greater amounts of PSE in the raw materials. Whether or not consumers would be willing to spend more for hams manufactured with low quantities of PSE will require further research.
4. Conclusions Sorting raw pork materials according to quality parameters (i.e., pH and PSE) impacts the processing yields and consumer appeal of products manufactured from those raw materials. Particular emphasis should be placed on selecting hams with pH values of 5.6 or greater for bone-in processing because their sliceability and water-holding properties will better withstand deterioration often associated with these products when they are frozen and then thawed. For boneless ham manufacturing, processing yields and defects were minimized when muscles containing high levels of PSE tissue were eliminated. Further research is needed to determine the optimal ratio of allowable PSE product in formulation that enables processors to maximize consumer appeal with the economic realities of sorting out PSE pork.
Acknowledgements Technical article from the Texas Agricultural Experiment Station. This study was supported, in part, by the American Meat Science Association, Savoy, IL on behalf of the National Pork Board and a number of pork genetic and processing companies.
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