Search
Author
Title
Vol.
Issue
Year
1st Page

Journal of Animal Science - Meat Science

Pork loin quality is not indicative of fresh belly or fresh and cured ham quality123

 

This article in JAS

  1. Vol. 94 No. 12, p. 5155-5167
     
    Received: Aug 09, 2016
    Accepted: Sept 20, 2016
    Published: November 17, 2016


    4 Corresponding author(s): dboler2@illinois.edu
 View
 Download
 Share

doi:10.2527/jas.2016-0886
  1. E. K. Arkfeld*,
  2. K. B. Wilson*,
  3. M. F. Overholt*,
  4. B. N. Harsh*,
  5. J. E. Lowell*,
  6. E. K. Hogan*,
  7. B. J. Klehm*,
  8. B. M. Bohrer*,
  9. D. A. Mohrhauser,
  10. D. A. King,
  11. T. L. Wheeler,
  12. A. C. Dilger*,
  13. S. D. Shackelford and
  14. D. D. Boler 4*
  1. * Department of Animal Sciences, University of Illinois, Urbana-Champaign, Champaign 61801
     Smithfield Foods, Denison, IA 51442
     USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933

Abstract

The objective was to characterize the relationship between fresh loin quality with fresh belly or fresh and cured ham quality. Pigs raised in 8 barns representing 2 seasons [cold (n = 4,290) and hot (n = 3,394)] and 2 production focuses [lean (n = 3,627) and quality (n = 4,057)] were used. Carcass characteristics and other meat quality data were collected on 7,684 carcasses. All of the carcasses were evaluated for HCW, LM depth, tenth rib fat depth, leg (ham primal) weight, instrumental color on the gluteus medius and gluteus profundus of the ham face, and subjective loin quality. Instrumental loin color and ultimate pH (≥ 22 h postmortem) were collected on the ventral side of loins along with dimensions and firmness scores of fresh bellies from 50% of the carcasses. Ten percent of the boneless loins and fresh hams were evaluated for slice shear force (SSF) or cured ham characteristics. Correlation coefficients between traits were computed using the CORR procedure of SAS and considered significantly different from 0 at P ≤ 0.05. Temperature decline, beginning at 31 min postmortem and concluding at 22 h postmortem, for the longissimus dorsi and semimembranosus muscles were evaluated on 10% of the carcasses. Ultimate loin pH was correlated with dimensional belly characteristics (r ≥ |0.07|; P < 0.0001) fresh ham instrumental color (r ≥ |0.03|; P ≤ 0.05), and semimembranosus ultimate pH (r = 0.33; P < 0.0001). Further, ultimate loin pH was correlated (P ≤ 0.01) with pump retention (r = 0.087) and cooked yield (r = 0.156) of cured hams. Instrumental L*on the ventral surface of the loin was related to L* on both muscles of the ham face (P ≤ 0.0001). Even though significant relationships between the loin, belly, and ham were detected, the variability in belly and ham quality explained by variability in loin quality was poor (≤ 22.09%). Compositional differences between the loin and belly may have contributed to those poor relationships. Additionally, differences in temperature declines during chilling between the loin and ham likely contributed to the weak nature of relationships. Equilibration of longissimus dorsi temperature to ambient cooler temperature occurred at 14 h postmortem (P = 0.0005), yet the semimembranosus had not equilibrated with ambient (equilibration bay) temperature (P < 0.0001) at 22 h postmortem. Using loin quality to draw conclusions about fresh belly and fresh and cured ham quality may be misleading.



INTRODUCTION

In recent years, the National Pork Board has emphasized a desire to implement a U.S. pork quality grading system. The loin is often used as the indicator of carcass quality. Historic quality evaluations have focused on the loin (Huff–Lonergan et al., 2002; Boler et al., 2010; Arkfeld et al., 2015) with little emphasis on quality of other primals. However, the belly and ham play a large role in determining total carcass value. Bacon is the most valuable pork retail cut (Bureau of Labor Statistics, 2016). Ham, though among the least valued pork primal on dollars per kg basis (USDA AMS, 2014), represents approximately 23.5% of the HCW (Lowe et al., 2014), therefore making it an important portion of carcass value. In order to develop a system to effectively sort carcasses or primal pieces into quality categories based on measurements in one primal, an understanding of the relationships among those pieces must be established. Correlation coefficients measure the linear relationship between 2 variables when neither can be easily defined as the dependent or independent variable (Kaps and Lamberson, 2009). Therefore, the objective was to determine the correlation between fresh loin quality and fresh belly or fresh and cured ham quality.

Given that the loin and ham are considered lean cuts, it was anticipated that consistency in the functionality of proteins would drive strong correlations between those 2 primals. Specifically, ultimate pH was expected to be highly correlated between the loin and ham. Previously, loin ultimate pH explained greater than 65% of the variation in subjective loin color, instrumental color, and purge loss (Bidner et al., 2004). Kemp et al. (1974) reported that fresh ham color was strongly correlated with cured ham traits, therefore it was anticipated that a strong relationship would exist between fresh loin and cured ham quality. However, it was anticipated that chilling differences between the ham and loin could compromise those relationships. Further, fresh bellies are comprised largely of adipose tissue. Thus, poor relationships between the loin and fresh belly quality were expected.


MATERIALS AND METHODS

Pigs were slaughtered under the supervision of the USDA Food Safety Inspection Service at a federally-inspected facility. Meat was purchased from that facility and transported to the University of Illinois Meat Science Laboratory or the USDA Meat Animal Research Center. Therefore, Institutional Animal Care and Use Committee approval was not necessary.

Pigs raised in 8 different barns (designated as A through H) representing 2 seasons and 2 production focuses were used in this study. Half of the barns were raised and slaughtered in a cold season and half of the barns were raised and slaughtered in a hot season. Half of the pigs slaughtered within each season were from the production focus aimed at lean growth and half were produced with a focus aimed at desirable meat quality. Investigators of this study were not made aware of management information regarding diet (aside from ractopamine inclusion), genotype, barn type, or floor space.

Pigs and Experimental Design

Pigs from barns A, B, C, and D were slaughtered over a 7 wk period in February and March (cold season). Similarly, in the hot season, pigs from barns E, F, G, and H were marketed over a 7 wk period from July through September. Producers of barns A, C, E, and G had production programs focused on lean growth of pigs, and barns B, D, F, and H had production programs focused on meat quality. Pigs selected for the meat quality focus were pigs that were identified by the packer from proprietary suppliers to provide proprietary genetics that resulted in loins with increased intramuscular fat compared with pigs in the lean growth focus. Loins from pigs in the meat quality focus had 0.95 subjective units more (P < 0.0001) marbling, were predicted to be more tender (P = 0.04), and had less purge loss (P = 0.03) than loins from pigs in the lean growth focus group (data not shown in tabular form). Similarly, pigs selected for the lean growth focus were pigs that were identified by the packer from proprietary suppliers to provide proprietary genetics that resulted in larger loins and greater estimates for carcass lean. Carcasses from pigs in the lean growth focus had 5.21-mm greater (P = 0.02) loin depths and 2.54 greater (P < 0.01) carcass lean estimates (data not shown in tabular form). Three groups were marketed from each barn following site specific protocols. Pigs were selected for each marketing group by producer designated criteria. The first, second, and third marketing groups from barns A and B were marketed on wk 1, 3, and 5, respectively. On wk 3, 5, and 7, marketing groups 1, 2, and 3, respectively, were marketed from barns C and D. Marketing schedules during the hot season followed the same pattern as the cold season with barns E and F having their first groups marketed during wk 1 and barns G and H having their first groups marketed during wk 3. This allowed for direct comparison of first marketing groups with second marketing groups and second marketing groups with third marketing groups by removing the uncertainty caused by day of slaughter. In line with producer and processing facility standard operating procedures, pigs in the second and third marketing groups of barns A and C received ractopamine at 5 mg/kg, but barns B, D, E, F, G, and H did not receive ractopamine at any time during finishing. Ractopamine does not influence color (7 of 8 studies reported no difference) or marbling (9 of 10 studies reported no difference) when fed at approved doses for use in the United States (Apple et al., 2007), so differences in meat quality relationships among selection focuses or marketing groups was not anticipated due to ractopamine.

Abattoir Data Collection

Lairage procedures followed normal operating procedures of the abattoir. Pigs of the quality production focus were lairaged overnight at the abattoir (approximately 13 h) and pigs selected for lean growth programs arrived at the abattoir approximately 7 h prior to slaughter. These differences were routine for those types of pigs at the abattoir because of the need to slaughter pigs whose meat qualified for a particular program at the same time. Pigs were rendered insensible by carbon dioxide stunning and terminated via exsanguination. Immediately after evisceration, carcasses were assigned a sequential identification number on the shoulder and ham, and each pig’s respective lot tattoo was recorded. Data were collected on 7,684 carcasses at the production facility (7,684 was the number of carcasses on which at least 1 data point was recorded; 100% data collection was not achieved for any specific trait, leading to the discrepancy in total number of observations for HCW, loin depth, fat depth, and leg weight). At 31 min postmortem, loin pH was collected at approximately the tenth rib on every tenth carcass (approximately 10% of the population). These carcasses were noted as the select pigs, used for in-depth analyses of loin and ham primal quality, as well as temperature decline of the longissimus dorsi and semimembranosus muscles. Thirty-one min postmortem pH data were collected with a REED SD-230 meter (Wilmington, NC) fitted with a PHE-2385 glass combo electrode (Omega; Stamford, CT) during the first and second weeks of the cold season and a FC 200 B series electrode (Hanna Instruments, Woonsocket, RI) was used for all remaining weeks of the study. At 31 min postmortem, temperature data loggers were inserted into the carcass (Thermochron-iButton-40C-thru-85C, Embedded Data Systems, Lawrenceburg, KY). The longissimus dorsi temperature data logger was placed at approximately the tenth rib in the same location pH was measured; semimembranosus temperature was measured posterior to the symphysis pubis bone; ambient temperature was recorded by attaching the data logger to a shroud pin in the spinous process of the thoracic vertebrae at approximately the fifth rib. Data loggers recorded the time and temperature at 1 min intervals. The data loggers were removed from the carcasses as the carcasses entered the cutting floor (approximately 22 h postmortem).

While carcasses chilled in the carcass equilibration bays, the vertebral column of all loins and the teat line of all bellies of odd sequence numbered carcasses were labeled with sequence numbers that matched the ham and shoulder. Approximately 22 h postmortem, carcasses were fabricated into primal pieces. Bellies [NAMP #408; North American Meat Processors (NAMP), 2007] and whole legs (modified NAMP # 401) were collected and placed into combos for further analyses that same day. Loins were fabricated into boneless Canadian back loins (NAMP #414). On the ventral side of the boneless loin, fresh muscle color (1 to 6 subjective scale), marbling (1 to 10 subjective scale), and firmness (1 to 5 subjective scale) were evaluated using NPPC standards on the loin boning and trimming line at the time of cutting by an industry professional with over 10 years of pork quality research experience (NPPC 1991; NPPC 1999). Color, marbling, and firmness scores were evaluated at a consistent location on the boning and trimming line to allow for a consistent bloom time. A subset (approximately 50%) of the loins were placed into a combo for further data collection.

Loins

Approximately 50% of the entire population of loins (odd numbered carcasses from above) was selected for further quality analyses and boneless primal weight. Instrumental L*, a*, and b* color evaluations were conducted on the ventral side at approximately 25% and 75% the length of the loin using a Hunter Miniscan XE Plus colorimeter (Hunter Lab, Reston, VA) with a D65 light source, 10° observer, and 25-mm port. Ultimate pH (> 22 h postmortem) was recorded using a pH meter. For data collected during the first wk of the cold season, a REED SD-230 meter (Wilmington, NC) fitted with a PHE-2385 glass combo electrode (Omega, Stamford, CT) was used. For all remaining ultimate pH measurements, data were collected with a HI 98160 Microprocessor Logging pH/ORP Meter (Hanna Instruments, Woonsocket, RI).

Approximately 10% of the entire population of loins (identified after evisceration from above) were vacuum-packaged, boxed, and transported to the Meat Animal Research Center (Clay Center, NE). Within 58 h of carcass cutting, loins arrived at USDA MARC. Loins were immediately placed on carts in a single-layer and ventral side up and aged (1 °C). Loins were weighed (tared for vacuum packaging bag) to record initial loin weight. At 20 d postmortem, loins were removed from their packaging and weighed to determine aged weight and purge loss was calculated: [({Initial weight, kg – aged weight, kg} / initial weight, kg) × 100]. At 20 d postmortem, loins were prepared for slicing with a Grasselli NSL 400 portion meat slicer. The posterior end of the loin (∼4 cm-long) was removed by a straight cut perpendicular to the length of the loin at a point 5-cm posterior to the anterior tip of gluteus accessories. The anterior end of the loin was removed by a second cut made 396-mm anterior to the first cut leaving a 396-mm-long center-cut loin section that fits the width of the Grasselli NSL 400 portion meat slicer. This approach maximized yield of chops with the greatest proportion of their mass/cross-sectional area comprised of longissimus and excluded chops with a high proportion of their mass/cross-sectional area comprised of other muscles (spinalis dorsi, multifidus dorsi, gluteus medius, and gluteus accessorius). Additionally, this approach standardized anatomical location of chop assignment across loins. Chops 5 and 6, which correspond approximately to the eleventh rib region of the loin, were used for determination of slice shear force (SSF). Immediately after cutting, fresh (never frozen) chops were weighed to record initial weight. The following day (21 d postmortem), chops were cooked using a belt grill (Magigrill, model TBG-60; MagiKitch’n Inc., Quakertown, PA) to a desired internal temperature of 71°C. Cooked chops were weighed and cooking loss was calculated: [({Initial weight, g – cooked weight, g} / initial weight, g) × 100]. Slice shear force (SSF) was measured using the procedures of Shackelford et al. (2004) on 2 chops. The 2 SSF values were then averaged.

Bellies

Skin-on bellies (NAMP #408) were weighed and measurements of belly length, depth, and width were recorded on approximately 50% of the bellies (odd-numbered carcasses from above). Belly depth (thickness) was measured at 25%, 50%, and 75% of the distance from the anterior toward the posterior end half way between the dorsal and ventral edge of the belly. Average belly depth was determined by averaging the 3 depth values. A subjective flop score of 0.5 (soft) through 5.0 (firm) in 0.5 unit increments was assigned to each belly. Subjective flop scores were anchored such that a score of 0.5 was characterized as an approximate flop distance of less than 5-cm, a score of 1 was 5.1 to 10-cm, a score of 2 was 10.1 to 15-cm, a score of 3 was 15.1 to 20-cm a score of 4 was 20.1 to 25-cm and a score of 5 was greater than 25-cm. Flop scores were assessed by trained plant personnel with at least 5 years of experience evaluating bellies.

Hams

Leg primal weight was recorded and instrumental L*, a*, and b* (Konica Minolta CR-400 colorimeter; Minolta Camera Company, Osaka, Japan; D65 light source, 0° observer, 8 mm aperture) measures were recorded on the gluteus medius and gluteus profundus of the ham face on approximately 100% of the hams in the population.

Select Hams

Fabrication and Quality Characteristics.

Select legs (targeted 10%) were transported in combos via refrigerated (£ 4 °C) truck to the University of Illinois Meat Science Laboratory where they were fabricated following procedures of Boler et al. (2011). Briefly, a modified NAMP #401 leg (rectus abdominus attached) was trimmed similar to a NAMP #402. Hams were then separated into 5 pieces: inside ham (NAMP #402F), outside ham (NAMP #402D), knuckle (NAMP #402H), inner shank portion (gastrocnemius muscle) and lite butt. Weights were recorded on all pieces. Identification of the inside, outside and knuckle was maintained; however, inner shank and lite butt identification was not retained as they were not needed for further analyses. Instrumental L*, a*, and b* values (Konica Minolta CR-400 colorimeter; Minolta Camera Company, Osaka, Japan; D65 light source, 0° observer, 8 mm aperture) and ultimate pH (MPI pH meter; Meat Probes Inc., Topeka, KS; 2 point calibration at pH 4 and 7) were collected on the semimembranosus muscle (blonde spot, medial side).

Ham Processing.

Each set of inside, outside, and knuckles originating from the same trimmed ham were stuffed into nylon nets and weighed to determine initial weight for the production of a NAMP #402G 3-piece hamThree-piece hams were injected with a multi-needle injector using a Schroder Injector Marinator model N50 (Wolf-Tec Inc., Kingston, NY) with a cure solution to a target of 120% of initial weight. Cure was formulated to include 1.52% salt, 0.33% sodium tripolyphosphate, 0.014% sodium nitrite, and 0.05% sodium erythorbate in the finished product. After injection, hams were immediately weighed to determine percent cure uptake. Hams were allowed to drain for 30 min on racks placed on a stainless steel table and hams were weighed again to determine final pump retention, and final pumped ham weight. Percent uptake (initial) and retention (final) were calculated as [(pumped weight – initial weight) / initial weight] × 100. Hams were allowed to equilibrate for at least 2 hours before they were macerated. After this time, hams were removed from the nylon net, macerated twice, placed in a plastic bag (as a complete set of inside, outside, and knuckle originating from the same ham) and tumbled under a vacuum for 2 h. After tumbling, ham pieces were stuffed into nets such that the outside portion was on the bottom of the ham, the inside portion was placed on top of the outside portion and the knuckle was placed in front of the inside and outside portions towards the factory clipped end of the netting. Hams were weighed to determine stuffed weight. Stuffed yield was calculated as (stuffed weight / initial weight) × 100. Hams were cooked in an Alkar smokehouse ([Lodi, WI) for 10 h to a targeted internal temperature of 65.6°C. After cooking, hams were showered with cold water and moved to a cooler where they were chilled to 4°C for at least 24 h. Hams were weighed with the casing removed to determine a final cooked weight. Final cook yield was calculated as (casing off cooked weight / initial weight) × 100 (Arkfeld et al., 2016).

Cured Ham Color.

A 2.54-cm thick ham steak was cut using a deli slicer approximately 75% of the distance from the factory clipped end of the ham such that no portion of the knuckle was visible in the steak. Instrumental L*, a*, and b* measures (Konica Minolta CR-400 colorimeter; Minolta Camera Company, Osaka, Japan; D65 light source, 0° observer, 8 mm aperture) were collected on the fresh cut surface of the further processed ham. The ham was visually divided into 4 quadrants by dividing the ham in half both vertically and horizontally, and a color measurement was recorded in each quadrant. Reported values are the average of the 4 measurements. Ham steaks were vacuum packaged and frozen at −20°C (Arkfeld et al., 2016).

Binding Strength.

Ham steaks used in cured ham color analysis were thawed at 4°C for 24 h. A standardized sample was prepared by cutting the sample 7.62-cm wide perpendicular to the seam of the inside and outside muscles of the ham steak. The steak was broken with constant force applied across the seam using a Texture Analyzer TA.HD Plus (Texture Technologies Corp., Scarsdale, NY; Stable Microsystems, Godalming, UK). Samples were broken with a 10-mm-diameter crossbar at a crosshead speed of 3.33-mm/s with a 3.81-cm platform gap and a 70-mm travel distance. The force necessary to break the bind is reported in kg (Arkfeld et al., 2016).

Proximate Composition.

Ham steaks, previously used for cured color and binding strength analyses, were homogenized in a food processor (Cuisinart, East Windsor, NJ)Moisture and extractible lipid analyses were performed in duplicate. Samples were dried in an oven at 110°C for at least 24 h and the lipid was extracted by washing the dried sample in an azeotropic mixture of warm chloroform:methanol. Protein concentrations were determined by measuring N content using the combustion method (Association of Official Analytical Chemists [AOAC], 2000; model TruMac, method 990.03, LECO Corp., St. Joseph, MI). Protein fat-free (PFF) was calculated as [% protein / (100 - % lipid)] × 100 (Arkfeld et al., 2016).

Statistical Analyses

This research targeted collection of data which was representative of the U.S. pork industry. Differing seasons of slaughter, production focuses, barns, and sexes were noted to indicate the applicability of this data to modern pork production. Given that variation in these traits is encountered in modern pork processing facilities, the aforementioned class variables will not be accounted for in the statistical model.

Correlation coefficients between longissimus dorsi and semimembranosus temperature decline were computed using the correlation option in the REG procedure of SAS. Correlations were considered significant at P ≤ 0.05. Summary statistics for variables used in loin correlations were computed using the MEANS procedure of SAS. Pearson correlation coefficients between loin quality and other carcass quality and composition traits were computed using the CORR procedure of SAS. Correlations were considered weak (in absolute value) at r < 0.35, correlations were considered moderate at 0.36 ≥ r < 0.67, and strong correlations were those r ≥ 0.68 (Taylor, 1990).

Temperature decline differences between the longissimus dorsi, semimembranosus, and ambient temperature of the equilibration bay were determined using the MIXED procedure of SAS (v.9.4, SAS Inst. Inc., Cary, NC). The model included the fixed effect of temperature recorder location (longissimus dorsi, semimembranosus, or ambient). Least square means were separated using the PDIFF option with a Tukey’s adjustment with alpha equal to 0.0001. Temperature differences were considered significantly different at P ≤ 0.0001.


RESULTS

Pearson Correlation Coefficients of Loin Quality with Fresh Belly Quality

Carcasses in the current study were representative of commercial carcasses in the U.S. pork supply (Table 1). Ultimate loin pH was not correlated with belly flop score (P = 0.51; Table 2), and weakly correlated (P < 0.0001) with belly length (r = 0.14), width (r = -0.20), and depth (r = -0.07). Relationships among 31 min loin pH and belly measures were also weak. Thirty-one min pH was correlated (P £ 0.02) with belly flop score (r = -0.08), length (r = -0.17), and width (r = 0.10). Subjective loin color was weakly correlated (P < 0.0001) with belly flop score (r = 0.20; Table 3), length (r = 0.24), width (r = -0.08), and depth (r = 0.13). The relationships among loin L* and belly traits were weaker than subjective color score and belly traits. Specifically, loin L* correlated (P < 0.0001) with flop score (r = 0.10) and width (r = -0.07) but was not correlated (P ≤ 0.07) with belly length or depth. Subjective marbling score was not correlated with belly width (P = 0.15), but was correlated (P < 0.0001) with belly flop score (r = 0.34), length (r = 0.22), and depth (r = 0.19).


View Full Table | Close Full ViewTable 1.

Population summary statistics of pork quality traits and cured ham quality

 
Variable n Mean SD Minimum Maximum CV
Loin quality
pH, 31 min 774 6.55 0.20 5.68 7.07 3.08
pH, 1d 3,990 5.69 0.15 5.37 6.79 2.56
Color, 1 d 7,381 3.09 0.56 1 5 18.27
Marbling, 1 d 7,381 2.13 0.92 0.5 6 43.35
Firmness, 1 d 7,381 2.75 0.62 1 5 22.49
Instrumental loin color1
    L* 3,937 52.66 2.49 44.3 62.05 4.73
    a* 3,937 7.40 1.15 2.94 11.41 15.55
    b* 3,937 13.64 1.04 9.92 17.63 7.61
Purge loss (%), 20 d 805 0.92 0.62 0.00 4.71 67.39
Cook loss (%), 21 d 818 17.28 2.01 8.4 23.15 11.64
Slice shear force, kg 818 14.80 5.50 5.9 39.51 37.16
Belly quality
Flop score2 3,646 2.05 0.84 0.5 5 40.95
Length, cm 3,648 69.24 4.31 52.71 84.46 6.23
Width, cm 3,647 35.91 2.45 27.31 44.45 6.81
Average depth, cm 3,648 2.53 0.42 0.85 4.02 16.59
Fresh ham quality
Gluteus profundus1
    L* 7,418 40.60 3.61 22.88 56.98 8.89
    a* 7,418 15.79 2.18 5.90 27.96 13.79
    b* 7,416 3.73 1.69 -4.64 14.04 45.25
Gluteus medius1
    L* 7,422 45.69 3.37 20.64 68.04 7.38
    a* 7,420 9.09 1.83 2.83 24.45 20.19
    b* 7,420 2.35 1.58 -4.23 20.15 67.48
Semimembranosus1
    L* 840 46.57 3.14 36.38 62.33 6.73
    a* 841 9.53 1.86 4.27 18.7 19.53
    b* 839 1.54 1.56 -4.12 9.43 101.22
    pH 842 5.66 0.28 4.68 7.07 4.97
Cured ham quality
Pump retention, % 840 16.87 3.27 6.69 36.44 19.41
Cooked yield, % 823 99.33 4.07 67.90 149.63 4.09
Cured color1
    L* 823 65.97 2.72 55.93 75.53 4.13
    a* 823 12.22 1.29 8.13 15.89 10.58
    b* 823 5.54 0.67 1.18 7.30 12.04
Bind strength, kg 792 7.76 1.99 2.62 17.39 25.70
Proximate composition
    Moisture, % 829 72.74 1.45 67.33 78.57 2.00
    Lipid, % 829 5.03 1.58 1.75 13.41 31.50
    Protein, % 825 18.99 1.10 15.6 22.25 5.77
    PFF, %3 825 20.00 1.10 16.06 23.05 5.51
1L* measures darkness to lightness (greater L* value indicates a lighter color). a* measures redness (greater a* value indicates a redder color). b* measures yellowness (greater b* value indicates a more yellow color). Fresh loin color values were the average of 2 readings per sample. Fresh ham color values were 1 reading per sample. Cured color values were the average of 4 readings per sample.
2A subjective flop score of 0.5 (soft) through 5.0 (firm) in 0.5 unit increments was assigned to each belly. Subjective flop scores were anchored such that a score of 0.5 was characterized as an approximate flop distance of less than 5 cm, a score of 1 was 5.1 to 10 cm, a score of 2 was 10.1 to 15 cm, a score of 3 was 15.1 to 20 cm a score of 4 was 20.1 to 25 cm and a score of 5 was greater than 25 cm.
3PFF = Protein fat-free = [% protein / (100 - % lipid)] × 100.

View Full Table | Close Full ViewTable 2.

Pearson correlation coefficients (r) of loin pH, water holding capacity, and tenderness with fresh belly characteristics1

 
Variable pH, 31 min pH, 1 d Purge loss, 20 d Cook loss, 21 d Slice shear force
Belly flop score2 −0.08 0.01 −0.22 −0.20 −0.35
(0.02) (0.51) (<0.0001) (<0.0001) (<0.0001)
Belly length −0.17 0.14 −0.25 −0.16 −0.19
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
Belly width 0.10 −0.20 0.15 0.00 0.03
(0.01) (<0.0001) (<0.0001) (0.98) (0.38)
Average belly depth −0.05 −0.07 −0.14 −0.20 −0.29
(0.16) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
1Upper row is the correlation coefficient between traits. P-value for difference from zero provided in parentheses.
2A subjective flop score of 0.5 (soft) through 5.0 (firm) in 0.5 unit increments was assigned to each belly. Subjective flop scores were anchored such that a score of 0.5 was characterized as an approximate flop distance of less than 5 cm, a score of 1 was 5.1 to 10 cm, a score of 2 was 10.1 to 15 cm, a score of 3 was 15.1 to 20 cm a score of 4 was 20.1 to 25 cm and a score of 5 was greater than 25 cm.

View Full Table | Close Full ViewTable 3.

Pearson correlation coefficients (r) of subjective loin color, marbling, and firmness with fresh belly characteristics1,2

 
Variable Color, 1 d Marbling, 1 d Firmness, 1 d Loin L*3 Loin a*3 Loin b*3
Belly flop score4 0.20 0.34 0.25 0.10 0.17 0.22
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
Belly length 0.24 0.22 0.05 0.03 0.03 0.09
(<0.0001) (<0.0001) (<0.01) (0.07) (0.07) (<0.0001)
Belly width −0.08 −0.02 0.03 −0.07 0.09 0.00
(<0.0001) (0.15) (0.08) (<0.0001) (<0.0001) (0.86)
Average belly depth 0.13 0.19 0.18 0.03 0.20 0.20
(<0.0001) (<0.0001) (<0.0001) (0.14) (<0.0001) (<0.0001)
1Upper row is the correlation coefficient between traits. P-value for difference from zero provided in parentheses.
2Loin measures were on the ventral side of the whole loin.
3L* measures darkness to lightness (greater L* value indicates a lighter color). a* measures redness (greater a* value indicates a redder color). b* measures yellowness (greater b* value indicates a more yellow color). Fresh loin color values were the average of 2 readings per sample.
4A subjective flop score of 0.5 (soft) through 5.0 (firm) in 0.5 unit increments was assigned to each belly. Subjective flop scores were anchored such that a score of 0.5 was characterized as an approximate flop distance of less than 5 cm, a score of 1 was 5.1 to 10 cm, a score of 2 was 10.1 to 15 cm, a score of 3 was 15.1 to 20 cm a score of 4 was 20.1 to 25 cm and a score of 5 was greater than 25 cm.

Pearson Correlation Coefficients of Loin Quality with Fresh and Cured Ham Quality

Relationship of Loin and Fresh Ham Traits.

Thirty-one min postmortem pH of loins was not correlated (P ≥ 0.17) with L* or a* values of either the gluteus medius or gluteus profundus, or semimembranosus L*, a*, or b* values (Table 4). There was a lack of correlation (P = 0.95) between 31 min loin pH and ultimate semimembranosus pH value. All L*, a*, b* values for gluteus profundus, gluteus medius, and semimembranosus were negatively correlated with ultimate loin pH (P ≤ 0.05; Table 3). Gluteus medius L* had the strongest correlation with ultimate loin pH (r = −0.34; P < 0.0001). Additionally, semimembranosus L* was correlated with 24 h loin pH at r = −0.28 (P < 0.0001). Semimembranosus pH was weakly correlated with loin pH at 24 h (r = 0.33; P < 0.0001). Further, semimembranosus pH was weakly, positively correlated with subjective marbling, color, and subjective firmness scores at 1 d postmortem (P ≤ 0.02; Table 5). Semimembranosus pH was not correlated with 1 d loin L* (P = 0.16).


View Full Table | Close Full ViewTable 4.

Pearson correlation coefficients (r) of loin pH, water holding capacity, and tenderness with fresh ham quality1

 
Variable pH, 31 min pH, 1 d Purge loss, 20 d Cook loss, 21 d Slice shear force
Gluteus profundus2
    L* 0.04 −0.14 0.12 0.20 0.09
(0.30) (<0.0001) (<0.01) (<0.0001) (0.01)
    a* −0.05 −0.03 −0.06 −0.07 −0.07
(0.17) (0.05) (0.12) (0.06) (0.05)
    b* 0.21 −0.14 0.16 0.19 0.18
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
Gluteus medius2
    L* −0.03 -0.34 0.14 0.23 0.05
(0.41) (<0.0001) (<0.01) (<0.0001) (0.12)
    a* 0.04 −0.08 0.05 0.02 0.04
(0.27) (<0.0001) (0.18) (0.48) (0.30)
    b* 0.11 −0.25 0.15 0.19 0.14
(<0.01) (<0.0001) (<0.0001) (<0.0001) (<0.01)
Semimembranosus2
    L* −0.05 −0.28 0.15 0.23 0.05
(0.20) (<0.0001) (<0.0001) (<0.0001) (0.14)
    a* −0.03 −0.15 0.11 0.08 0.04
(0.42) (<0.0001) (<0.01) (0.02) (0.21)
    b* 0.00 −0.27 0.21 0.17 0.05
(0.97) (<0.0001) (<0.0001) (<0.0001) (0.19)
    pH 0.00 0.33 −0.30 −0.36 −0.22
(0.95) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
1Upper row is the correlation coefficient between traits. P-value for difference from zero provided in parentheses.
2L* measures darkness to lightness (greater L* value indicates a lighter color). a* measures redness (greater a* value indicates a redder color). b* measures yellowness (greater b* value indicates a more yellow color). Fresh ham color values were one reading per sample.

View Full Table | Close Full ViewTable 5.

Pearson correlation coefficients (r) of subjective loin color, marbling, and firmness with fresh ham quality1,2

 
Variable Color, 1 d Marbling, 1 d Firmness, 1 d Loin L*3 Loin a*3 Loin b*3
Gluteus profundus3
    L* −0.14 0.06 −0.07 0.15 −0.04 0.07
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (0.01) (<0.0001)
    a* 0.05 0.02 0.03 0.00 0.11 0.08
(<0.0001) (0.07) (0.02) (0.98) <0.0001 (<0.0001)
    b* −0.04 0.06 −0.03 0.05 0.11 0.09
(<0.01) (<0.0001) (0.01) (<0.01) (<0.0001) (<0.0001)
Gluteus medius3
    L* −0.29 0.00 −0.12 0.33 −0.06 0.22
(<0.0001) (0.75) (<0.0001) (<0.0001) (<0.01) (<0.0001)
    a* 0.10 0.07 0.05 −0.19 0.27 −0.04
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001) (0.01)
    b* −0.07 0.04 −0.02 0.04 0.18 0.12
(<0.0001) (<0.01) (0.06) (0.01) (<0.0001) (<0.0001)
Semimembranosus3
    L* −0.21 -0.02 −0.08 0.31 −0.06 0.25
(<0.0001) (0.57) (0.02) (<0.0001) (0.10) (<0.0001)
    a* 0.04 −0.06 0.01 −0.15 0.31 0.02
(0.26) (0.11) (0.74) (<0.0001) (<0.0001) (0.64)
    b* −0.09 −0.03 −0.01 0.08 0.16 0.15
(0.01) (0.44) (0.82) (0.03) (<0.0001) (<0.0001)
    pH 0.13 0.12 0.08 −0.05 −0.07 −0.02
(<0.01) (<0.01) (0.02) (0.16) (0.03) (0.57)
1Upper row is the correlation coefficient between traits. P-value for difference from zero provided in parentheses.
2Loin measures were on the ventral side of the whole loin.
3L* measures darkness to lightness (greater L* value indicates a lighter color). a* measures redness (greater a* value indicates a redder color). b* measures yellowness (greater b* value indicates a more yellow color). Fresh loin color values were the average of 2 readings per sample. Fresh ham color values were 1 reading per sample.

Overall, relationships between loin color and ham color were moderate to weak in nature. Significant (P < 0.0001; Table 5) relationships existed between loin L* and ham muscle L* measures; loin L* positively correlated with L* of the gluteus profundus (r = 0.15), gluteus medius (r = 0.33), and semimembranosus (r = 0.31). Further, day 1 loin a* values were significantly correlated with ham muscle a* values (P < 0.0001). With increased 1 d loin a* values, there was an increase (P < 0.0001) in gluteus profundus (r = 0.11), gluteus medius (r = 0.27), and semimembranosus (r = 0.31) a* values. Day 1 subjective color values were associated with decreased L* in the gluteus profundus (r = -0.14), gluteus medius (r = -0.29), and semimembranosus (r = -0.21; P < 0.0001).

Relationship of Loin and Cured Ham Traits.

Ultimate loin pH was weakly, positively correlated (P ≤ 0.01) with pump retention (r = 0.09) and cooked yield (r = 0.16; Table 6). Cook loss was correlated (P < 0.01) with moisture content (r = -0.14), but no other proximate composition traits (P ³ 0.08). Slice shear force was not correlated (P > 0.77) with pump retention or cooked yield, but had weak correlations (P £ 0.01) with cured ham color L* (r = 0.16) and lipid content of the ham (r = -0.13).


View Full Table | Close Full ViewTable 6.

Pearson correlation coefficients (r) of loin pH, water holding capacity, and tenderness with cured ham quality1

 
Variable pH, 31 min pH, 1 d Purge loss, 20 d Cook loss, 21 d Slice shear force
Ham pump retention 0.02 0.09 −0.11 −0.05 −0.01
(0.59) (0.01) <0.01 (0.13) (0.86)
Ham cooked yield 0.05 0.16 −0.11 −0.11 −0.01
(0.15) (<0.0001) (<0.01) (<0.01) (0.77)
Cured ham color2
    L* 0.21 −0.22 0.18 0.20 0.16
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
    a* 0.06 −0.02 0.03 0.03 0.03
(0.11) (0.59) (0.38) (0.33) (0.40)
    b* −0.04 −0.25 0.07 0.15 −0.06
(0.28) (<0.0001) (0.05) (<0.0001) (0.12)
Ham bind strength 0.00 −0.03 −0.04 −0.01 0.00
(0.94) (0.37) (0.31) (0.75) (0.94)
Ham proximate composition
    Moisture 0.02 0.15 −0.04 −0.14 0.02
(0.59) (<0.0001) (0.28) (<0.01) (0.53)
    Lipid −0.02 −0.04 −0.11 0.03 −0.13
(0.51) (0.26) (<0.01) (0.44) (<0.01)
    Protein −0.10 −0.07 0.09 0.05 0.02
(<0.01) (0.04) (0.04) (0.16) (0.49)
    PFF3 −0.11 −0.09 0.06 0.06 −0.01
(<0.01) (0.01) (0.10) (0.08) (0.72)
1Upper row is the correlation coefficient between traits. P-value for difference from zero provided in parentheses.
2L* measures darkness to lightness (greater L* value indicates a lighter color). a* measures redness (greater a* value indicates a redder color). b* measures yellowness (greater b* value indicates a more yellow color). Cured color values were the average of 4 readings per sample. Cured color values were the average of 4 readings per sample.
3PFF =Protein fat-free = [% protein / (100 - % lipid)] × 100.

Day 1 loin L*, a*, and b* correlated (P < 0.01; Table 7) with cured ham color L* (r = 0.11), a* (r = 0.33), and b* (r = 0.18), respectively. Percent moisture of cured, cooked ham was consistently negatively correlated to all instrumental loin color measures (P < 0.01). Percent lipid was positively correlated to instrumental and subjective color (P < 0.01). Protein fat-free was correlated (P < 0.01) with loin L* (r = 0.13) and b* (r = 0.15), but not loin a* (P = 0.12).


View Full Table | Close Full ViewTable 7.

Pearson correlation coefficients (r) of loin color, marbling, and firmness with cured ham quality1,2

 
Variable Color, 1 d Marbling, 1 d Firmness, 1 d Loin L*3 Loin a*3 Loin b*3
Ham pump retention 0.06 −0.01 −0.04 −0.01 −0.05 0.00
(0.08) (0.85) (0.24) (0.87) (0.15) (0.92)
Ham cooked yield 0.14 0.09 0.03 −0.13 0.06 −0.10
(<0.0001) (0.01) (0.36) (<0.01) (0.10) (0.01)
Cured ham color3
    L* −0.22 0.00 −0.02 0.11 −0.09 −0.01
(<0.0001) (0.90) (0.60) (<0.01) (0.01) (0.78)
    a* 0.14 −0.03 0.00 −0.28 0.33 −0.13
(<0.0001) (0.36) (0.93) (<0.0001) (<0.0001) (<0.01)
    b* −0.02 −0.03 −0.01 0.09 0.15 0.18
(0.67) (0.38) (0.81) (0.01) (<0.0001) (<0.0001)
Ham bind strength 0.01 0.03 −0.05 0.03 0.00 0.05
(0.86) (0.36) (0.16) (0.38) (0.96) (0.13)
Ham proximate composition
    Moisture −0.03 −0.28 −0.11 −0.16 −0.12 −0.21
(0.39) (<0.0001) (<0.01) (<0.0001) (<0.01) (<0.0001)
    Lipid 0.17 0.47 0.16 0.17 0.15 0.22
(<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001) (<0.0001)
    Protein −0.14 −0.22 −0.03 0.07 −0.09 0.08
(<0.01) (<0.0001) (0.37) (0.05) (0.01) (0.02)
    PFF4 −0.09 −0.09 0.01 0.13 −0.06 0.15
(0.01) (0.01) (0.68) (<0.01) (0.12) (<0.0001)
1Upper row is the correlation coefficient between traits. P-value for difference from zero provided in parentheses.
2Loin measures were on the ventral side of the whole loin.
3L* measures darkness to lightness (greater L* value indicates a lighter color). a* measures redness (greater a* value indicates a redder color). b* measures yellowness (greater b* value indicates a more yellow color). Fresh color values were the average of 2 readings per sample. Cured color values were the average of 4 readings per sample.
4PFF = Protein fat-free = [% protein / (100 - % lipid)] × 100.

Muscle Temperature Decline

Equilibration of longissimus dorsi temperature to ambient (carcass equilibration bay) temperature (approximately 1 °C) occurred at 14 h postmortem (P = .0005; Table 8; Fig. 1), yet the semimembranosus had not equilibrated with ambient temperature (P < 0.0001) at 22 h postmortem when the carcasses were fabricated. At this time point, semimembranosus temperature was 1°C greater than ambient temperature and 1.76°C greater than loin temperature. Further, the relationship of the deep muscle temperatures differed over time between the 2 muscles (Fig. 2). At 35 min postmortem, the correlation coefficient of the longissimus dorsi temperature with the semimembranosus temperature was 0.37, indicating only a moderate relationship between the 2 muscles. This relationship weakened through the blast chill process until the lowest relationship at 2 h postmortem (r = 0.05). Large differences in temperature before 14 h (Fig. 1; Table 8) likely drove this weak correlation. Specifically, during blast chilling (31 min to 2 h postmortem), loins were colder than hams and the correlation between muscle temperatures was weak (Fig. 2); however, as loins equilibrated with ambient temperature (14 h postmortem) and hams began to approach ambient temperature, the relationship between the temperature of the longissimus dorsi and semimembranosus became stronger. The strongest relationship between semimembranosus and longissimus dorsi temperatures occurred at 15 h postmortem (r = 0.74; Fig. 2), 1 h after the longissimus dorsi reached equilibration with ambient temperature. The relationship between the 2 muscles weakened as the ham temperature continued to decline and the loin temperature remained within 0.5°C of its 15 h postmortem temperature.


View Full Table | Close Full ViewTable 8.

Least square means of temperature decline of the longissimus dorsi muscle, semimembranosus muscle, and surrounding ambient temperature of 775 carcasses during the first 22 h postmortem

 
Time, h:min Longiss-imus dorsi, °C Semimem-branosus, °C Ambient, °C SEM P-value
0:31 37.07b 39.40a 15.73c 0.13 <0.0001
1:00 34.77b 38.84a −14.79c 0.10 <0.0001
2:00 18.96b 29.82a −11.83c 0.16 <0.0001
3:00 10.32b 23.86a −0.55c 0.12 <0.0001
4:00 6.66b 20.52a 1.34c 0.10 <0.0001
5:00 4.94b 17.92a 1.89c 0.08 <0.0001
6:00 3.90b 15.66a 1.84c 0.07 <0.0001
7:00 3.14b 13.76a 1.59c 0.07 <0.0001
8:00 2.54b 12.11a 1.39c 0.06 <0.0001
9:00 2.05b 10.71a 1.06c 0.06 <0.0001
10:00 1.63b 1.63b 0.86c 0.05 <0.0001
11:00 1.26b 8.34a 0.54c 0.05 <0.0001
12:00 0.95b 7.33a 0.46c 0.05 <0.0001
13:00 0.69b 6.42a 0.19c 0.05 <0.0001
14:00 0.47b 5.59a 0.23b 0.05 <0.0001
15:00 0.33b 4.87a 0.32b 0.05 <0.0001
16:00 0.24c 4.26a 0.64b 0.04 <0.0001
17:00 0.25c 3.78a 1.04b 0.04 <0.0001
18:00 0.32c 3.39a 1.11b 0.04 <0.0001
19:00 0.40c 3.05a 1.09b 0.04 <0.0001
20:00 0.48c 2.79a 1.21b 0.03 <0.0001
21:00 0.57c 2.57a 0.57b 0.03 <0.0001
22:00 0.61c 2.37a 1.37b 0.03 <0.0001
a–cMeans with differing superscripts differ at P ≤ 0.0001.
Figure 1.
Figure 1.

Temperature decline of the longissimus dorsi muscle, semimembranosus muscle, and surrounding ambient temperature of 775 carcasses during the first 22 h postmortem.

 
Figure 2.
Figure 2.

Pearson correlation coefficients (r) between the longissimus dorsi and semimembranosus muscle temperatures during the first 22 h postmortem.

 


DISCUSSION

A significant caveat for the interpretation of statistical relationships between 2 traits is to avoid the conclusion of a cause-and-effect relationship (Taylor, 1990). Cause and effect relationships can be more appropriately described with coefficients of determination, which allows for a more thorough interpretation of the relationship. A coefficient of determination can be calculated by squaring the correlation coefficient. This provides a calculation for the percentage of the variation of the dependent variable that can be explained by the independent variable (Taylor, 1990). Because historic norms dictate that carcass quality is determined by loin quality, loin quality traits serve as the independent variable in this discussion.

A strong relationship between the quality traits of the loin, belly, and ham would be ideal in pork processing as it would allow implementation of a system to sort whole carcasses into quality-based value-added programs at the industry level. For example, a strong relationship between loin quality and belly quality would offer opportunity to identify quality bellies using loin quality indicators. Given that sliced bacon prices have sharply increased since 2010, and are currently the most expensive retail pork product (Bureau of Labor Statistics, 2016), selection of carcasses that possess both quality loins and bellies would be ideal.

It was hypothesized that loin and belly quality would not be related, due to loin quality being driven by pH and fresh belly quality being a function of adipose tissue quality. Specifically, Bidner et al. (2004) reported that ultimate loin pH explained 70% of the variation in subjective loin color, 68% of the variation in instrumental loin color, and 77% of the variation in loin purge loss. Conversely, Kyle et al. (2014) reported significant correlations among belly flop distance and percent lipid (r = 0.60) and iodine value (r = −0.58), indicating that belly flop distance is related to adipose tissue quality. The results of the present study indicated that only weak relationships between loin and fresh belly existed. The strongest correlation between loin and fresh belly quality indicated that variability in loin slice shear force measures only accounted for 8.41% of the variability in average belly depth. Therefore, selecting carcasses solely on loin quality will not result in the concurrent selection of carcasses with high quality bellies.

It was hypothesized that strong correlations would exist between loin quality and fresh and cured ham quality. Chemical composition of the loin and ham are more similar than the loin and belly. As reported by Mitchell et al. (1998), percent lean of the loin region was 64.46% and the ham was 72.60% (carcasses in this study were not separated into NAMP primals, rather the carcass was separated into shoulder, loin, side, and ham regions). These primals are a greater percent protein than the side (belly) region which was 59.72% lean (Mitchell et al., 1998). Therefore, given that proteins function in a similar manner, independent of their locations within the pork carcass, it was expected that strong correlations would occur between loin and ham quality traits. This hypothesis was further supported by the results of Warriss et al. (2006) that indicated L* measures made on the cut surface of the pork adductor exposed during splitting of the pork carcass explained 59% of the variation in loin quality (overall loin quality scale ranging from 1 = dark, firm, and dry to 5 = pale, soft, and exudative). The study by Warriss et al. (2006) was specifically designed to maximize variation in ham color and quality attributes (hams ranged from pale, soft, and exudative, to dark, firm, and dry). In the present study, however, only weak correlations existed. These correlations did follow normal biological patterns. For example, as loin L* increased (became paler) fresh ham muscles also became paler. However, these relationships were not strong enough to be meaningful in a commercial processing facility, as variability in loin instrumental L* accounted for no greater than 10.59% of the variability in L* of ham instrumental L* values. Given that weak correlations were observed between loin quality and fresh ham quality, it was not surprising to observe a similar result between loin quality and cured ham quality. This was clearly illustrated by the weak relationship between ultimate loin pH and cured color L* where variability in loin pH only accounted for 4.84% of the variability in cured color L*. Thus, selecting carcasses with quality loins does not equate to the selection of carcasses with high quality fresh or cured hams. The results of this study would further indicate that other factors contribute variation to the postmortem conversion of muscle to meat, and therefore drive the weak relationships between loin and fresh ham quality.

A potential explanation may be loins and hams chilled differently affecting meat quality relationships between the loin and ham, therefore driving the weak nature of primal quality relationships. Differences in muscle temperature declines have impacted pork quality in the past. A study conducted by Springer et al. (2003) compared a conventional spray chill system with blast chilling for 60, 90, 120, or 150 min, and concluded that improvements in pork loin quality could be made using blast chilling, a more rapid chilling method, for carcasses. Specifically, loins from blast chilled carcasses had greater subjective firmness and color scores when compared with spray chilled carcass; however, there was no difference due to chilling on purge, drip loss, or thaw loss in the loin (Springer et al., 2003). Shackelford et al. (2012) observed differences in pigs sourced from a single barn and genetic line; pigs with carcasses that chilled more rapidly (blast chill) had greater loin purge loss and were less tender (15 d postmortem) than carcasses chilled in a conventional spray chill system. However, cured and cooked ham quality characteristics were largely unaffected by chill type (Springer et al., 2003). In the current study, differences in temperature decline between loins and hams were observed. Specifically, loins reached equilibration with ambient temperature (approximately 1°C) of the equilibration bay at 14 h postmortem. Yet, at 22 h postmortem, when carcasses were fabricated, hams temperature had not equilibrated with ambient temperature of the equilibration bay. The hypothesis, that chilling differences resulted in weak correlations between loin and ham quality, is further substantiated by weak correlations between ham and loin temperature. After reaching a peak correlation of r = 0.74 at 15 hr postmortem, the relationship between the temperature of the 2 muscles continued to deteriorate until carcasses were fabricated at 22 h. The current study clearly indicated differences in muscle temperature at various time points within the same carcass.

Conclusions

Loin quality traits were correlated with quality traits of the belly, fresh ham and processed ham, but loin quality traits explained very little of the variability in belly, fresh ham or cured ham quality. The lack of strong correlations between the loin and ham may be due to differences in chilling rates. Loins reached ambient temperature at approximately 14 h postmortem, but hams did not reach ambient temperatures, even after 22 h of chilling. Lack of relationships between the loin and belly may be due to compositional differences. Fresh bellies may be as much as 40% extractible lipid while loins are likely no more than 5% extractible lipid. Using loin quality to draw conclusions about belly, fresh ham, or cured ham quality may be misleading. A carcass with a high quality loin will not necessarily yield a high quality belly or ham. To understand whole carcass quality, loin, belly, fresh ham, and cured ham quality must be evaluated individually.

 

References

Footnotes


Comments
Be the first to comment.



Please log in to post a comment.
*Society members, certified professionals, and authors are permitted to comment.