I. H. Hwang

The postmortem factors like rate of glycolysis and muscle shortening have a major role on meat characteristics and these have been efficiently manipulated by methods like chilling regime, electrical stimulation and different hanging. These methods have been optimized with time leaving a little scope for further improvement. During the harvesting process of meat there is a generalized cell death often referred to as necrosis or apoptosis. This process of cell death has been well studied with respect to various physiological functions in vivo but its role in postmortem meat quality has received little attention. It is mainly regulated by caspases and also probably by calpains, cathepsins, proteasomes, lysosomal enzymes and other molecules, antioxidants and stress proteins. The term apoptosis appears to be more appropriate as evident by involvement of the enzyme systems and cell shrinkage. Further, examination of postmortem events effecting meat quality and correlating them to understand the cell death process may reveal the possible involvement of both apoptosis and necrosis processes, one preceding the other. This manuscript is an attempt to review the apoptotic process of various cell lines and possible implication for muscle cells after slaughter and meat quality control.PRACTICAL APPLICATIONS: Understanding the intricate biochemical mechanisms governing cell death processes after slaughter may help us provide better solutions for pre‐slaughter animal handling and postslaughter interventions to manage meat toughness. Investigations on these tracks would distinguish muscle cell death processes after slaughter from apoptosis or necrosis, and consequently may lead to enhanced technological meat quality as available literature suggests that a number of molecules such as caspase family are likely to be involved in cell death process after slaughter and also in meat tenderization.

Research on barley as an animal feed started some decades ago but its utilization in animal production has been limited

Summary: Pigmentation genes such as TYR (tyrosinase), TYRP1 (tyrosinase‐related protein 1), DCT (previously TYRP2, or tyrosinase‐related protein 2), ASIP (agouti) and MC1R (melanocortin receptor 1) play a major role in cattle coat colour. To understand the genotypic profile underlying coat colour in native Korean Hanwoo cattle and Angus black cattle, portions of the above‐mentioned genes were amplified. Sequence analysis revealed variation in the TYRP1 (exon 5) and MC1R genes. Restriction enzyme analysis of these two genes could distinguish between different colours of Hanwoo cattle. Quantitative estimates of melanin and eumelanin in hair from three different‐coloured Hanwoo phenotypes and Angus black showed significant differences at the breed and phenotypic levels. Finally, sequence variants in MC1R were associated with total melanin and eumelanin in breeds as well as in Hanwoo phenotypes.

Coat colours in cattle have been of interest to both breeders and researchers as genes regulating pigmentation not only affect the phenotype but also have economic implications in the event of genetic mutations. The genes controlling pigmentation act as a complex and interact with each other to cause phenotypic and genotypic variations. Pigmentation of coat broadly depends on the ratio of eumelanin and pheomelanin, the two components of melanin. Increase in eumelanin imparts a black coat colour while raise in pheomelanin is responsible for a yellowish or reddish colour. The main enzymes responsible for melanogenesis are regulated by the genes of the tyrosinase family. It is speculated that the wild‐type gene present in the ancestral breeds of the present day cattle have more pheomelanin content and that, over time, mutations have introduced more variations leading to many shades. This could have occurred either because of interactions or because of deletions in the responsible genes. The environmental conditions have also contributed to mutations in these genes, helping in the adaptability of the animals to different geographical regions. The switching between the syntheses of melanin components depends on several genes like melanocortin‐1receptor gene (MC1r) – also known as melanocyte‐stimulating hormone receptor gene (MSHr)‐, agouti (A), attractin (Atrn) and mahogunin (Mgrn1). The purpose of this review is to summarize the recent advances in the field of pigment biology and to highlight possible areas of research that may benefit a breeder or a farmer in the selection of animals on the basis of phenotype.

The current study was conducted to evaluate carcass characteristics, objectives and sensory meat qualities of Hanwoo longissimus muscle as affected by ultimate pH. Twenty-four steers and bulls (556±53 kg and 0.63±0.32 cm for live weight and backfat thickness, respectively) were used. As there was a linear relationship (r = 0.77) between lean meat color and ultimate pH, cattles were thus segregated into normal (pH≤5.8, Normal, n = 13) and DFD (pH>5.8, n = 11) groups. Normal pH group had significantly (p<0.05) higher carcass weight, marbling score and backfat thickness than those for high pH group, while fat color and lean meat color were inverse. In principle component analysis for coordinates of DFD and normal meats, fat color, lean meat color, texture, time to pH 6.2 and pH at 24 h postmortem were associated with the positive range of the first factor (67.5%) while backfat thickness marbling score and temperature at 24 h were placed in negative values. The rate constant of decline in pH (pH k) did not differ between the two groups, implying that initial pH (i.e., pH at slaughtering) differed between two groups. Contour mapping of pH k between pH at 1 and 24 h postmortem indicated that high pH k was related to lower pHs at 1 and 24 h postmortem. This suggested that the high pH cattles (i.e., DFD cattle) resulted from their own potential. Although the time to reach pH 6.2 was significantly (p<0.05) shorter for normal meat (i.e., 3.2 h) than that for DFD one (i.e., 19.8 h), there were no significantly differences in both WB-shear force and sensory attributes. Given that the experimental animals were sampled from a similar group, which implies a similar myoglobin pigment content, the current data suggested that pre-and post-slaughter animal handling likely had a significant effect on ultimate pH and consequently meat color of Hanwoo longissimus muscle, and also small animals with lower marbling score and backfat thickness had a higher risk for DFD meat.

The current study was conducted to investigate the optimum stunning voltage and chilling regime with emphasis on reduction in pale, soft and exudative (PSE) pork. The experiments were conducted at seven Korean major pig abattoirs using a total of 91,082 industrial population. Frequencies of PSE meat was found to be significantly (p<0.05) increased as stunning voltage was elevated from 220-240 (13.14%), 250-280 (29.32%) to 430 volts (36.74%). Chilling methods after slaughter, either with cold water showing or rapid chilling reduced PSE meat by 22% compared to a classic chiller-based slow chilling regime. The current study also revealed that chiller temperature during the first 90 minutes had a significant (p<0.001) effect on PSE incidences. Pigs chilled between-5 to 7°C resulted in the lowest PSE meat (17.8%), followed by higher than 7°C (21.3%) and lower than-5°C (37.5%). The current data implies that low voltage stunning method (eg., 220-240 volts), followed by rapid chilling regime, maintaining chiller temperature between approximately-5 to 7°C could reduce PSE incidences.

"Fibre Type of Korean Native Pork and Its Effects on Post-Mortem Proteolysis" published on 01 Nov 2006 by Wageningen Academic.