Postmortem protein degradation is a key contributor to fresh pork loin tenderness

Abstract

The objective of this study was to determine factors that influence tenderness independent of variation in pH, color, or marbling. To achieve the objective, 2 sample groups were chosen from a population of 159 pork loins aged 11 to 16 d. Predetermined ranges (ultimate pH, 5.54 to 5.86; marbling score, 1.0 to 3.0; percent total lipid, 1.61 to 3.37%) were defined for inclusion of individual loins in the study. The pork loins with the greatest (n = 12) and least (n = 12) Instron star probe values were assigned to 2 classification groups. The high star probe group had an average star probe that was 2.8 kg greater than the low star probe group (7.75 vs. 4.95 kg). Pork quality and sensory characteristics of pH, subjective and instrumental color values, cook loss, sensory tenderness, chewiness, juiciness, pork flavor, and off flavor were determined on fresh, never frozen pork chops. Lipid content, sarcomere length, myosin heavy-chain profile, and calpain autolysis were determined. Degradation of troponin-T, desmin, filamin, and titin were evaluated on the protein extracts from each sample. Pork loin pH, subjective color scores, Minolta L values, sarcomere length, and myosin heavychain composition were not different across groups. Chops from the low star probe group had a significantly greater marbling score (2.3 vs. 1.9) and lipid content (2.61 vs. 2.23%). Calpain-1 was completely autolyzed in both high and low star probe samples, demonstrating that calpain-1 potentially had been active in all samples. Low star probe whole-muscle protein extracts had more troponin-T (P < 0.01), desmin (P < 0.01), and filamin degradation (P < 0.01) than high star probe samples. Both classification groups showed degradation of titin. Remarkably, some high star probe samples still had observable intact bands of titin on SDS-PAGE gels. These results demonstrate that significant variation in instrumental tenderness is observed within a moderate pH range. Lipid content and proteolysis both appear to contribute to this variation.

Proteome changes in lamb semimembranosus muscles associated with the inclusion of sunflower cake in their diet

“…Moreover, the disappearance of the structural proteins could be indicating more proteolysis. These differences in myofibrillar protein degradation might lead to a variation in tenderness as previously reported in pork (Carlson et al ., ). However, molecular differences sometimes produce no effect at macroscopic level.…”

Effect of a dual enteric and respiratory pathogen challenge on swine growth, efficiency, carcass composition, and pork quality1

“…Rate of troponin -T degradation has been documented to be inversely related to WBSF in pork (Szalata et al, 2005). Carlson et al (2017b) reported 26 % less abundant intact troponin-T in low star probe samples than high star probe samples (P < 0.01) in aged pork chop samples. Abundance of the 30-kDa degradation band and 27 -30 kDa degradation product of troponin-T in low star probe samples was more than double the abundance of troponin-T degradation products in high star probe samples (P < 0.01).…”

“…These fibers were also larger in cross sectional area when compared to the fibers in distal locations. It has been well documented that postmortem degradation of troponin-T (Huff- Carlson et al, 2017b) and desmin Melody et al, 2004;Rowe et al, 2004a;Carlson et al, 2017a;Carlson et al, 2017b) is linked to meat tenderness.…”

Expression analyses of candidate genes related to meat quality traits in squabs from two breeds of meat‐type pigeon

“…Up till now, many efforts have been made to identify possible candidate genes effecting fat‐related traits. FASN (fatty acid synthase), LPL (lipoprotein lipase), FABP3 (fatty acid‐binding protein 3, also known as heart‐type FABP, H‐FABP) , and FABP4 (fatty acid‐binding protein 4, also known as adipocyte FABP, A‐FABP ) have been regarded to be associated with intramuscular fat (IMF) deposition (Gao & Zhao, ; Yamada, ), while members of the calpain (CAPN) family, CAPN1 , CAPN2 , and CAST (calpastatin), are considered to be closely related to post‐mortem meat tenderness (Carlson et al., ; Lian, Wang, & Liu, ). Also, many documents showed the associations between polymorphisms on these genes and meat traits in meat‐producing animals (Gao et al., ; Liang et al., ; Oh et al., ; Pinto et al., ; Rempel, Casas, Shackelford, & Wheeler, ; Ye, Chen, Zhao, Zheng, & Wen, ).…”