Effect of hot carcass weight on loin, ham, and belly quality from pigs sourced from a commercial processing facility,

A new manual method for pork belly firmness measurement

A new objective and standardized method for early determination of firmness of the intact pork belly in a research environment is described, and compared to the existing bar-bend method. The belly characteristics that contribute to the outcome of each method, and the relationship between the two methods are identified. •Original method requires a ribbed pork belly, and several minutes relaxation time.•New method provides an immediate measurement on an intact belly.•Advantages include early, rather than late, application in the fabrication process; rapid measurement; standardization; measurements minimally affected by animal length or belly length.

A large-scale comparison of the meat quality characteristics of different chicken breeds in South China

Meat quality traits are essential for producing high-quality broilers, but the genetic improvement has been limited by the complexity of measurement methods and the numerous traits involved. To systematically understand the meat quality characteristics of different broiler breeds, this study collected data on slaughter performance, skin color, fat deposition, and meat quality traits of 434 broilers from 12 different breeds in South China. The results showed that there was no significant difference in the live weight and slaughter weight of various broiler breeds at their respective market ages. Commercial broiler breeds such as Xiaobai and Huangma chickens had higher breast muscle and leg muscle rates. The skin and abdominal fat of Huangma chickens cultivated in the consumer market in South China exhibited significantly higher levels of yellowness compared to other varieties. Concerning fat traits, we observed that Wenchang chickens exhibited a strong ability to fat deposition, while the younger breeds showed lower fat deposition. Additionally, there were significant positive correlations found among different traits, including traits related to weight, traits related to fat, and skin color of different parts. Hierarchical clustering analysis revealed that fast-growing and large broiler Xiaobai chickens formed a distinct cluster based on carcass characteristics, skin color, and meat quality traits. Principal component analysis (PCA) was used to extract multiple principal components as substitutes for complex meat quality indicators, establishing a chicken meat quality evaluation model to differentiate between different breeds of chickens. At the same time, we identified 46, 22, and 20 SNP loci and their adjacent genes that were significantly associated with muscle mass traits, fat deposition, and skin color through genome-wide association studies (GWAS). The above results are helpful for systematically understanding the differences and characteristics of meat quality traits among different breeds.

Carcass and meat quality traits and their relationships in Duroc × Landrace × Yorkshire barrows slaughtered at various seasons

To understand characteristics of carcass traits and meat quality in pig population, 22 indicators of carcass characteristics and meat quality traits were measured on 278 Duroc × Landrace × Yorkshire barrows that were slaughtered in different seasons (spring, summer, autumn and winter). The effects of body weight and season on carcass characteristics and meat quality were analyzed by GLM procedure, followed the Bonferroni multiple test. The phenotypic correlations among those traits were calculated by employing the CORR procedure. In addition, the linear regression equations were constructed by stepwise regression model in REG procedure. The results showed that pigs slaughtered in spring had the heaviest body weight among the four seasons (P < 0.05), pigs slaughtered in summer had the lowest backfat depth and shear force (P < 0.05), and pigs slaughtered in winter had the lowest drip loss (P < 0.05). The results showed more variation in backfat depth, drip loss, intramuscular fat content, and shear force, compared with other indicators across pigs. Body weight had a significant association with loin eye area, average backfat depth and L^⁎_{24 h} (P < 0.05). Furthermore, regression equations for drip loss, cooking loss, shear force, and intramuscular fat content were constructed using more accessible indicators. Collectively, this study provided an overall view of carcass and meat quality traits in a commercial pig population in China, and illustrated that season significantly affected carcass characteristics and meat quality traits independently of body weight.

Differences in carcass chilling rate underlie differences in sensory traits of pork chops from pigs with heavier carcass weights

Pork hot carcass weights (HCW) have been increasing 0.6 kg per year, and if they continue to increase at this rate, are projected to reach an average weight of 118 kg by the year 2050. This projection in weight is a concern for pork packers and processors given the challenges in product quality from heavier carcasses of broiler chickens. However, previous work demonstrated that pork chops from heavier carcasses were more tender than those from lighter carcasses. Therefore, the objective was to determine the effects of pork hot carcass weights, ranging from 90 to 145 kg with an average of 119 kg, on slice shear force and sensory traits of Longissimus dorsi chops when cooked to 63°C or 71°C, and to assess if differences in chilling rate can explain differences in sensory traits. Carcasses were categorized retrospectively into fast, medium, or slow chilling-rates based on their chilling rate during the first 17 h postmortem. Loin chops cut from 95 boneless loins were cooked to either 63°C or 71°C and evaluated for slice shear force and trained sensory panel traits (tenderness, juiciness, and flavor) using two different research laboratories. Slopes of regression lines and coefficients of determination between HCW and sensory traits were calculated using the REG procedure in SAS and considered different from 0 at P ≤ 0.05. As hot carcass weight increased, chops became more tender as evidenced by a decrease in SSF (63°C ß = -0.0412, P = 0.01; 71°C ß = -0.1005, P < 0.001). Further, HCW explained 25% (R 2 = 0.2536) of the variation in chilling rate during the first 5 h of chilling and 32% (R 2 = 0.3205) of the variation in chilling rate from 5 h to 13 h postmortem. Slow and medium-rate chilling carcasses were approximately 12 kg heavier (P < 0.05) than fast chilling carcasses. Slice shear force of chops cooked to 63° and 71°C was reduced in slow and medium chilling compared with fast chilling carcasses. Carcass temperature at 5 h postmortem explained the greatest portion of variation (R 2 = 0.071) in slice shear force of chops cooked to 63°C. These results suggest that carcasses tend to chill slower as weight increases, which resulted in slight improvements in sensory traits of boneless pork chops regardless of final degree of doneness cooking temperature.

Effects of feeding high oleic soybean oil to growing-finishing pigs on growth performance and carcass characteristics

Feeding growing-finishing pigs supplemental fat is a common practice in the swine industry and can result in improved feed efficiency and reduced feed intake; however, dietary lipids also play a key role in determining pork composition. The objectives of the current study were to evaluate the effects of feeding graded levels of high oleic soybean oil (HOSO) on growth performance and carcass characteristics. A total of 288 pigs raised in two separate blocks (144 pigs each) were assigned to one of four diets containing either 25% dried distiller's grains with solubles (DDGS), 2% high oleic soybean oil (HOSO2), 4% high oleic soybean oil (HOSO4), or 6% high oleic soybean oil (HOSO6). Pigs were housed 4 per pen and fed for 98 d using a 3-phase feeding system. Pigs were individually weighed and feed intake was recorded throughout the trial to calculate average daily feed intake (ADFI) and gain to feed ratio (G:F). A total of 144 pigs were transported to the University of Illinois Meat Science Laboratory and fabricated into primal and subprimal cuts to calculate carcass cutting yields. Differences in growth performance were observed, with pigs fed the DDGS treatment exhibiting greater (P ≤ 0.01) overall ADFI consuming 0.21, 0.18, and 0.28 kg/d more than HOSO2, HOSO4, and HOSO6 diets, respectively. Pigs fed the HOSO6 diet had greater (P ≤ 0.03) overall G:F than pigs fed DDGS and HOSO2 diets but did not differ (P = 0.12) from pigs fed HOSO4. Furthermore, differences in carcass traits were observed. Hot carcass weight was increased (P ≤ 0.03) in pigs fed the HOSO6 diet compared with pigs fed the DDGS and HOSO2 diets, while pigs fed HOSO4 did not differ (P > 0.05) from either extreme. Additionally, pigs fed HOSO4 and HOSO6 produced fatter (P ≤ 0.01) carcasses with reduced (P ≤ 0.01) standardized fat-free lean. Minimal differences were observed in primal weights expressed as a percentage of chilled side including bone-in Boston butt, trimmed loin, and trimmed ham with primal weights decreasing with increasing inclusion of dietary HOSO. Overall, pigs fed HOSO2 had reduced ADFI with similar backfat thickness and standardized fat-free lean compared with pigs fed the DDGS treatment. However, pigs fed HOSO 4% and 6% not only had improvements in ADFI and G:F but also had increased backfat thickness, which resulted in reductions in standardized fat-free lean and primal weights expressed as a percentage of chilled side weight.

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.

Effects of various pre-slaughter weights on the physico-chemical qualities of pig meat

Objective:

The article aimed to study the relationship between the physico-chemical qualities of pig meat and their pre-slaughter weights.

Materials and Methods:

In this study, 60 pigs were reared for fattening under the same conditions of keeping and feeding, slaughtered, and used to sample the longest back muscle meat with pre-slaughter weights of 110 and 130 kg. The samples were evaluated according to generally accepted methods for assessing the physico-chemical qualities in pig meat.

Results:

Samples of meat from animals slaughtered at 130 kg had higher values for marbling – by 2.0 points or 5.24% (p < 0.01), active acidity pH in ham muscles – by 0.20 pH or 3.57% (p < 0.01), and the longest muscle of the back – by 0.10 pH or 1.82% (p < 0.001). The pre-slaughter weight factor substantially affected the pH of ham muscles at 10.35% and on the marbling of meat in the longest back muscle at 13.31%. Pigs slaughtered at 110 kg had a greater increase in the color intensity of the meat and an increase in its water holding capacity. At a pre-slaughter weight of 130 kg, increasing the marbling and decreasing the softness of the flesh demonstrated a modest, adverse relationship.

Conclusion:

The findings support the use of pre-slaughter weight management to enhance pork quality.

The relationship of pork carcass weight and leanness parameters in the Ontario commercial pork industry

This study aimed to examine the correlation of carcass weight, fat depth, muscle depth, and predicted lean yield in commercial pigs. Data were collected on 850,819 pork carcasses from the same pork processing facility between October 2017 and September 2018. Hot carcass weight was reported following slaughter as a head-on weight; while fat and muscle depth were measured with a Destron PG-100 probe and used for the calculation of predicted lean yield based on the Canadian Lean Yield (CLY) equation [CLY (%) = 68.1863 - (0.7833 × fat depth) + (0.0689 × muscle depth) + (0.0080 × fat depth²) - (0.0002 × muscle depth²) + (0.0006 × fat depth × muscle depth)]. Descriptive statistics, regression equations including coefficients of determination, and Pearson product moment correlation coefficients (when assumptions for linearity were met) and Spearman's rank-order correlation coefficients (when assumptions for linearity were not met) were calculated for attributes using SigmaPlot, version 11 (Systat Software, Inc., San Jose, CA). Weak positive correlation was observed between hot carcass weight and fat depth (r = 0.289; P < 0.0001), and between hot carcass weight and muscle depth (r = 0.176; P < 0.0001). Weak negative correlations were observed between hot carcass weight and predicted lean yield (r = -0.235; P < 0.0001), and between fat depth and muscle depth (r = -0.148; P < 0.0001). Upon investigation of relationships between fat depth and predicted lean yield, and between muscle depth and predicted lean yield using scatter plots, it was determined that these relationships were not linear and therefore the assumptions of Pearson product moment correlation were not met. Thus, these relationships were expressed as nonlinear functions and Spearman's rank-order correlation coefficients were used. A strong negative correlation was observed between fat depth and predicted lean yield (r = -0.960; P < 0.0001), and a moderate positive correlation was observed between muscle depth and predicted lean yield (r = 0.406; P < 0.0001). Results from this dataset revealed that hot carcass weight was generally weakly correlated (r < |0.35|) with fat depth, muscle depth, and predicted lean yield. Therefore, it was concluded that there were no consistent weight thresholds where pigs were fatter or heavier muscled.

Effects of Increased Pork Hot Carcass Weights. II: Loin Quality Characteristics and Palatability Ratings

The objective of this study was to evaluate the effects of increased pork hot carcass weight on loin quality and palatability of top loin chops. Pork loins (N = 200) were collected from 4 different hot carcass weight groups: A light weight (LT; less than 111.8 kg), medium-light weight (MLT; 111.8 to 119.1 kg), medium-heavy weight (MHVY; 119.1 to 124.4), and a heavyweight group (HVY; 124.4 and greater). Following fabrication, chops were assigned to fat and moisture analysis, Warner-Bratzler shear force (WBSF), consumer sensory panels, or trained sensory panels. Chops from the HVY group were rated as more (P < 0.05) tender compared to chops from the LT carcasses. Additionally, chops from the HVY weight group had greater (P < 0.05) consumer overall like ratings compared to chops from both the LT and MLT groups. Carcass weight did not affect (P > 0.05) consumer flavor liking ratings. Hot carcass weight treatment did not contribute (P > 0.05) to the percentage of chops rated acceptable for flavor and overall liking. The greatest (P < 0.05) percentage of samples were rated acceptable for juiciness for chops from the HVY weight group, and the lowest (P < 0.05) percentage of acceptable ratings for tenderness were for chops from the LT weight group. Both initial and sustained juiciness from MHVY carcasses were rated as more (P < 0.05) juicy compared to chops from both MLT and LT carcasses by trained sensory panelists. Additionally, chops from the LT carcasses had the lowest (P < 0.05) myofibrillar tenderness ratings. Chops from MHVY and HVY carcasses were similar (P > 0.05), with greater (P < 0.05) overall tenderness ratings compared to chops from LT carcasses. These results indicate chops from heavier weight carcasses may have improved tenderness and juiciness compared to chops from lighter carcasses.

Effects of Increased Pork Hot Carcass Weights. I: Chop Thickness Impact on Consumer Visual Ratings

The objective of this study was to evaluate the effect of increased pork hot carcass weights on consumer visual acceptability and purchase intent ratings of top loin chops cut to various thicknesses in a price labeled versus unlabeled retail display scenario. Pork loins (N = 200) were collected from 4 different hot carcass weight groups: light weight (LT; less than 111.8 kg), medium-light weight (MLT; 111.8 to 119. kg), medium-heavy weight (MHVY; 119.1 to 124.4 kg), and a heavy weight group (HVY; 124.4 kg and greater). Loins were fabricated into 4 pairs of chops of specified thicknesses (1.27, 1.91, 2.54, and 3.18 cm). One chop from each pair was assigned to be packaged with or without a label. Consumers assessed chops for appearance, desirability, and purchase intent. For both appearance and purchase intent ratings, chops from HVY carcasses were given more desirable (P < 0.05) ratings compared to LT chops. Consumers gave greater (P < 0.05) appearance ratings to thicker cut chops. There was a hot carcass weight × chop thickness interaction (P < 0.05) for the percentage of consumers that indicated the chop was desirable overall. Regardless of hot carcass weight group, chops with a thickness of 1.27 cm had the lowest (P < 0.05) percentage of consumers indicate they were desirable overall. A greater (P < 0.05) percentage of consumers indicated “yes” they would purchase chops cut to a thickness of 2.54 cm compared to all other thicknesses. Additionally, there was a greater (P < 0.05) percentage of consumers who indicated they would purchase unlabeled chops compared to labeled chops. These results, within the population sampled, indicate that carcass weight and chop thickness can affect consumer preference and thus should be considered by retailers when marketing fresh pork loin chops.

Characterizing Ham and Loin Quality as Hot Carcass Weight Increases to an Average of 119 Kilograms

The objective was to characterize ham and loin quality of carcasses ranging from 78 to 145 kg (average ∼119 kg). Hot carcass weight (HCW), back fat depth, and loin depth was measured on 666 carcasses. Loin pH, instrumental and visual color and iodine value of clear plate fat (all 3 layers) was measured on approximately 90% of the population. Quality measurements of the ham, 14 d aged loin and chop, and loin chop shear force (SSF) were evaluated on approximately 30% of the population. Myosin heavy chain fiber type determination was completed on 49 carcasses. Slopes of regression lines and coefficients of determination between HCW and quality traits were calculated using the REG procedure in SAS and considered significantly different from 0 at P ≤ 0.05. As HCW increased, loin depth (b1 = 0.2496, P < 0.0001), back fat depth (b1 = 0.1374, P < 0.0001), loin weight (b1 = 0.0345, P < 0.0001), and ham weight (b1 = 0.1044, P < 0.0001) increased. Estimated lean (b1 = –0.0751, P < 0.0001) and iodine value (b1 = –0.0922, P < 0.0001) decreased as HCW increased, where HCW accounted for 24% (R2 = 0.24) of the variation in estimated lean and 7% (R2 = 0.07) of the variation in iodine value. However, HCW did not explain variation in ham quality traits (P > 0.15) and did not explain more than 1% (R2 ≤ 0.01) of the variation in 1 d loin color or pH. Loins from heavier carcasses were more tender (decreased SSF; b1 = –0.0674, P < 0.0001), although HCW only explained 9% of the variation in SSF. Hot carcass weight did not alter (P > 0.22) muscle fiber type percentage or area. These results suggest that increasing HCW to an average of 119 kg did not compromise pork quality.

Effect of hot carcass weight on the rate of temperature decline of pork hams and loins in a blast-chilled commercial abattoir123

Adequate carcass chilling is required to optimize pork quality and food safety. The rate at which carcasses chill is dependent on their mass. Hot carcass weight has increased steadily over the years, certainly affecting the chilling rate of the average carcass in contemporary abattoirs. Therefore, the objective was to model the effect of HCW on temperature decline of a contemporary population of pork carcasses slaughtered at a commercial abattoir that used a blast-chilling method. In addition, carcasses were sorted into HCW classes, and the effect of HCW group was tested on the rate of temperature decline of the longissimus dorsi and semimembranosus. Hot carcass weight, internal temperature of the loin muscle (at the 10th rib) and ham, as well as ambient temperature, were recorded from 40 to 1,320 min postmortem (45 time points) on 754 pork carcasses. An exponential decay model based on Newton's law of cooling,  T(t)=Ta+(T0-Ta)e-kt, was fit to temperature decline of the ham and loin of the whole population using PROC MODEL of SAS. The initial models for the decline of both ham and loin temperature displayed significant autocorrelation of errors based on evaluation of the autocorrelation function plots and Durbin-Watson test (P < 0.0001). Therefore, second- and third-order autocorrelation parameters were tested. Based on Durbin-Watson test, the use of second-order autocorrelation model with lags of 1 and 2 was deemed adequate and was therefore included in all subsequent models. This base model and its respective parameter estimates were all significant (P < 0.01) for the whole population. Carcasses approximating 85, 90, 95, 100, and 105 kg (± 1 kg) were selected and binned into their respective weight classes. Dummy variables were used to compare the effect of HCW class on parameter estimate of ham and loin models. The developed model significantly fit all weight classes (P < 0.01) for both ham and loin temperature decline. For both loin and ham models, estimates of the rate constant (k) generally decreased as HCW increased. For loin temperature, k estimate for 105-kg carcasses was 0.00124 less (P = 0.02) than 85-kg carcasses, with the intermediate HCW classes not differing from the 85-kg class. For ham temperature, estimates of k for 90, 95, 100, and 105 kg HCW were all significantly and successively less than the k estimate for 85 kg class. For perspective, loins of 95-kg carcasses were estimated to reach 2 °C in 17 h, whereas loins from 105-kg carcasses would not reach 2 °C until 27 h. For hams, 95-kg carcasses were projected to reach 2 °C in 21 h, whereas those from 105-kg carcasses would take 28 h. Overall, HCW significantly affects the rate of temperature decline of pork hams, but not loins from pork carcasses weighing between 85 and 100 kg.