Relationships among early postmortem loin quality and aged loin and pork chop quality characteristics between barrows and gilts

Comparison of an advanced automated ultrasonic scanner (AutoFom III) and a handheld optical probe (Destron PG-100) to determine lean yield in pork carcasses

This study compared the accuracy of two methods for predicting carcass leanness (i.e., predicted lean yield) with fat-free lean yields obtained by manual carcass side cut-out and dissection of lean, fat, and bone components. The two prediction methods evaluated in this study estimated lean yield by measuring fat thickness and muscle depth at one location with an optical grading probe (Destron PG-100) or by scanning the entire carcass with advanced ultrasound technology (AutoFom III). Pork carcasses (166 barrows and 171 gilts; head-on hot carcass weights (HCWs) ranging from 89.4 to 138.0 kg) were selected based on their fit within desired HCW ranges, their fit within specific backfat thickness ranges, and sex (barrow or gilt). Data (n = 337 carcasses) were analyzed using a 3 × 2 factorial arrangement in a randomized complete block design including the fixed effects of the method for predicting lean yield, sex, and their interaction, and random effects of producer (i.e., farm) and slaughter date. Linear regression analysis was then used to examine the accuracy of the Destron PG-100 and AutoFom III data for measuring backfat thickness, muscle depth, and predicted lean yield when compared with fat-free lean yields obtained with manual carcass side cut-outs and dissections. Partial least squares regression analysis was used to predict the measured traits from image parameters generated by the AutoFom III software. There were method differences (P < 0.01) for determining muscle depth and lean yield with no method differences (P = 0.27) for measuring backfat thickness. Both optical probe and ultrasound technologies strongly predicted backfat thickness (R2 ≥ 0.81) and lean yield (R2 ≥ 0.66), but poorly predicted muscle depth (R2 ≤ 0.33). The AutoFom III improved accuracy [R2 = 0.77, root mean square error (RMSE) = 1.82] for the determination of predicted lean yield vs. the Destron PG-100 (R2 = 0.66, RMSE = 2.22). The AutoFom III was also used to predict bone-in/boneless primal weights, which is not possible with the Destron PG-100. The cross-validated prediction accuracy for the prediction of primal weights ranged from 0.71 to 0.84 for bone-in cuts and 0.59 to 0.82 for boneless cut lean yield. The AutoFom III was moderately (r ≤ 0.67) accurate for the determination of predicted lean yield in the picnic, belly, and ham primal cuts and highly (r ≥ 0.68) accurate for the determination of predicted lean yield in the whole shoulder, butt, and loin primal cuts.

Relationship between Inherent Cooking Rate and Warner-Bratzler Shear Force of Pork Chops Cooked to Two Degrees of Doneness

The objective was to test inherent cooking rate differences on tenderness values of boneless pork chops when exogenous factors known to influence cooking rate were controlled. Temperature and elapsed time were monitored during cooking for all chops. Cooking rate was calculated as the change in °C per minute of cooking time. Warner-Bratzler shear force (WBSF) was measured on chops cooked to either 63 °C or 71 °C. Slopes of regression lines and coefficients of determination between cooking rate and tenderness values for both degrees of doneness (DoD) were calculated. Shear force values decreased as cooking rate increased regardless of DoD (p ≤ 0.05), however changes in tenderness due to increased cooking rate were limited (β1 = −0.201 for 63 °C; β1 = −0.217 for 71 °C). Cooking rate only explained 3.2% and 5.4% of variability in WBSF of chops cooked to 63 °C and 71 °C, respectively. Cooking loss explained the most variability in WBSF regardless of DoD (partial R² = 0.09–0.12). When all factors were considered, a stepwise regression model explained 20% of WBSF variability of chops cooked to 63 °C and was moderately predictive of WBSF (model R² = 0.34) for chops cooked to 71 °C. Overall, cooking rate had minimal effect on pork chop tenderness.

Final internal cooking temperature of pork chops influenced consumer eating experience more than visual color and marbling or ultimate pH

The objective was to determine the effect of "quality grade" (combination of visual color and marbling) or ultimate pH on consumer eating experience of pork chops cooked to different final internal temperatures. The hypothesis was that consumers would rate a greater percentage of pork chops as acceptable when graded "choice," had a greater ultimate pH, or when cooked to 63 °C compared with chops graded "standard," had a lesser ultimate pH, or when cooked to 71 or 82 °C. Consumers (264 total) were served chops in 1 of 2 experiments. Chops in Exp. 1 were classified as "choice" when NPPC visual color score ≥3 and visual marbling score was ≥2 or "standard" when NPPC scores did not meet the qualifications for "choice" and were cooked to either 63 or 71 °C. Chops in Exp. 2 were categorized as high pH (5.88 to 6.23) or low pH (5.36 to 5.56) and cooked to 63, 71, or 82 °C. Chops were cooked with a sous-vide device (ANOVA Precision Cooker, Anova Applied Electronics, San Francisco, CA) in a water bath. Consumers used a 9-point Likert-type score system where scores 1 through 3 were considered not tender, not juicy, not flavorful, or unacceptable. Scores 4 through 6 were consider neutral for tenderness, juiciness, flavor, and overall acceptability. Scores 7 through 9 were considered tender, juicy, flavorful, and acceptable. Data were organized as a percentage of responses and analyzed using the GLIMMIX procedure of SAS for both experiments with models including treatment (quality grade, ultimate pH, and final internal temperature) and all interactions. Quality grade did not affect (P ≥ 0.30) consumer ratings for any sensory trait. More (P < 0.01) consumers rated chops with a high pH (36.07%) as juicy compared with chops with a low pH (24.29%), but pH category did not alter (P ≥ 0.13) perceptions for tenderness, flavor, or overall acceptability. In both studies, a greater (P < 0.001) percentage of consumers rated chops cooked to 63 °C as acceptable compared with chops cooked to 71 °C. Therefore, internal cooking temperature has a greater impact on consumer eating experience than "quality grade" or ultimate pH.

Growth performance, carcass characteristics, fresh belly quality, and commercial bacon slicing yields of growing-finishing pigs from sire lines intended for different industry applications

The objective was to control intrinsic and extrinsic factors associated with the production and slaughter of pigs to determine effects of sire line (Pietrain vs. Duroc ancestry) on growth performance, carcass and belly characteristics, and commercial bacon yields of growing-finishing pigs. There were no differences in growth performance (P ≥ 0.08) or belly processing characteristics (P ≥ 0.09). Pietrain sired pigs had a greater lean yield (P ≤ 0.01). Duroc sired pigs had darker, more highly marbled loins (P ≤ 0.04) and thicker bellies (P < 0.001). Bacon from Pietrain sired pigs had a greater (P = 0.04) lean to fat ratio with 1.58% increase (P = 0.04) in average bacon slice lean. Barrows had more highly marbled loins (P ≤ 0.01) and thicker bellies (P < 0.001) than gilts. Bacon from barrows had a greater slice area (P < 0.001) while bacon from gilts had a greater lean to fat ratio (P = 0.04).

Correlation comparisons among early postmortem loin quality and aged loin and pork chop quality characteristics between finishing pigs from either Duroc or Pietrain sires

Today, the United States exports 2.2 million tons of pork and pork products annually, representing just over 26% of U.S. pork production. In order to meet specific demands of a growing export market, pork quality and carcass characteristics are now integrated into breeding objectives. Color and marbling are 2 loin quality traits that influence consumer acceptability of pork and while correlations between early and aged ventral quality have been established, it is unclear if those correlations differ between production objectives (meat quality vs. lean growth). Therefore, the objective of this experiment was to compare correlations among early postmortem ventral loin quality characteristics and aged ventral loin and chop quality characteristics between pigs sired by either Pietrain (lean growth) or Duroc (meat quality) boars. Early postmortem (~1 d) quality traits included: instrumental and visual color, marbling and firmness, and loin pH on the ventral surface of the loin. Loins were aged until 14 d postmortem in vacuum packages. Aged quality traits included traits evaluated early as well as Warner-Bratzler shear force (WBSF) and cook loss. Correlations were compared between Pietrain and Duroc-sired pigs using a Fisher's z-test. Early instrumental lightness (L*) was moderately correlated with aged ventral L* (Pietrain r = 0.47; Duroc r = 0.65) and aged ventral visual color (Pietrain r = 0.42; Duroc r = 0.58). Early ventral visual color was moderately correlated with aged chop L* (Pietrain r = 0.46; Duroc r = 0.60) and aged chop visual color (Pietrain r = 0.45; Duroc r = 0.57). Early visual marbling was strongly correlated (Pietrain r = 0.68; Duroc r = 0.84) with aged chop visual marbling. Within the Duroc-sired pigs, early L* was moderately correlated with aged chop L* (r = 0.64) but only weakly correlated (r = 0.35) within the Pietrain-sired pigs and those correlations differed at P ≤0.02. Within the Duroc-sired pigs, early ventral visual color was moderately correlated with aged pH (r = 0.44) and aged ventral L* (r = 0.57) but only weakly correlated (r ≤ 0.29) within the Pietrain-sired pigs and those correlations differed at P ≤0.03. No early postmortem quality traits were correlated (|r| ≤ 0.34) with WBSF or cook loss for either sire line. In summary, correlations between early and aged postmortem quality traits rarely differed between Duroc- and Pietrain-sired pigs. It is not necessary to account for sire line when relating early and aged quality characteristics.

Rapid Communication: Effect of machine, anatomical location, and replication on instrumental color of boneless pork loins

The objective was to determine the effect of machine, anatomical location, and replication (multiple readings) on instrumental color and to characterize the amount of variation each factor contributed to overall color. Instrumental color was measured three times on the anterior and three times on the posterior end of 250 pork loins with two different Minolta CR-400 Chroma meter devices. Each Minolta was programed to use a D65 illuminant, 2° observer with an 8 mm aperture, and calibrated with white tiles specific to each machine. Therefore, a total of 12 instrumental color measurements were collected on each loin. The VARCOMP procedure in SAS was used to estimate the proportion of variation contributed by each factor to CIE L*, a*, b*, chroma, and hue. Based on previous research, the average untrained consumer is able to distinguish between 3-L* units, 0.4-a* units, and 0.9-hue angle units. Loins evaluated with machine 1 were 0.71 L* units darker (P < 0.01), 1.09 b* units more yellow (P < 0.01), 0.47 chroma units more saturated (P < 0.01), and had a hue angle 5.12 units greater (P < 0.01) than when evaluated with machine 2 but did not differ (P = 0.24) in redness. The anterior portion of the loin was lighter, less red, more yellow, more saturated and had a greater hue angle than the posterior end (P < 0.01). All color trait values decreased (P < 0.01) as replication number increased. Inherent color differences among loins contributed the greatest proportion of variability for lightness (58%), redness (57%), yellowness (70%), saturation (70%), and hue angle (49%). Machine contributed 1% variability to lightness 3% to saturation, 23% to yellowness, and 31% to hue angle (31%) but did not contribute to variability for redness. Anatomical location contributed 41% to lightness, 43% to redness, 7% to yellowness, 27% to saturation, and 31% to hue angle. Replication did not contribute to total variation for any color traits, even though it did differ among measurements. Overall, there were differences in instrumental color values between the two machines tested, but those differences were likely less than the threshold for detection by a consumer. Even so, inherent color differences between loins were a greater contributor to total variability than the differences between the two machines. Therefore, it is more important to define the location of measurements than replication or machine when using a Minolta CR-400 when performing color evaluations, assuming the settings are the same.

Effect of packaging type during postmortem aging and degree of doneness on pork chop sensory traits of loins selected to vary in color and marbling

The objective was to determine the interactions between packaging type and degree of doneness on sensory traits of pork loins classified based on the newly proposed USDA quality grades. A total of 144 loins were selected from 2 groups of pigs (lean growth or meat quality production focus) to represent as much variation in visual color and marbling as possible. Selection was achieved with a VQG grading camera. The ventral surface of the loins was evaluated for loin quality traits at 1 d postmortem. At 2 d postmortem loins were sliced into 28-mm-thick chops. Chop within each loin was randomly assigned to either individual vacuum packages or to individual Styrofoam trays and overwrapped in polyvinyl chloride (PVC) oxygen permeable film. Overwrapped PVC packages were then placed in bulk packages and flushed with a gas mixture that contained approximately 0.4% carbon monoxide, 30% carbon dioxide, and 80% nitrogen. Vacuum-packaged chops were aged until 14 d postmortem. Chops packaged in PVC overwrap were aged until 9 d postmortem in the bulk packages, then placed on simulated retail display until 14 d postmortem. Chops from each packaging type were cooked to an internal temperature of either 63 °C or 71 °C for the evaluation of slice shear force (SSF) or for evaluation of tenderness, juiciness, and flavor by a trained panel. Data were analyzed as split-split plot design with production focus of the pigs, proposed USDA quality grade, packaging type, and degree of doneness as fixed effects. While there were main effect differences between production focuses, there were no interactions with production focus. There were also no 3-way (P ≥ 0.19) interactions and only one 2-way interaction among quality grade, packaging type, or degree of doneness. There were no differences in sensory tenderness (P = 0.30), juiciness (P = 0.49), flavor (P = 0.89), SSF (P = 0.13), or cook loss (P = 0.06) among USDA quality grades. There were no differences in sensory tenderness (P = 0.06), juiciness (P = 0.32), flavor (P = 0.74), SSF (P = 0.99), or cook loss (P = 0.12) between chops aged in vacuum packages or PVC packages. Chops cooked to 63 °C were 4.6% more tender (P < 0.0001), 10.1% juicier (P < 0.0001), and 2.9% less flavorful (P = 0.01) than chops cooked to 71 °C. These data suggest that cooking chops to 63 °C rather than 71 °C was a more effective way to improve tenderness and juiciness than selecting chops of a certain quality grade or altering packaging postmortem.