Changes in tenderness and cathepsins, activity during post mortem ageing of yak meat

Very little research has been conducted on yak meat tenderization. In this study we investigated the changes in physical characteristics (e.g., pH, water-holding capacity, texture profile analysis, shear force) and cathepsins L, B and H activities in the tenderization process. These traits were quantified in longissimus dorsi muscle from 10 yaks during 192 h post mortem. Samples were aged at 4 degrees C for 0, 12, 24, 36, 48, 72, 120, 168 and 192 h. pH decreased (P <0.05) from 6.84 to 5.54 in the first 72 h and did not change significantly during the next 120 h. Water-holding capacity showed an overall decreasing trend (P <0.05). Shear force decreased? (P <0.05) and myofibrillar fragmentation index increased? (P <0.05), and it was concluded that ageing can improve yak meat tenderness. Our results on texture profile analysis showed a decrease in hardness (P <0.0 5), springiness (P <0.0 5) and chewiness (P <0.05), reflected in a progressive softening during ageing (P <0.05). Cathepsins L, B and H activity showed an increased trend (P <0.05). In conclusion, our results show potential roles for cathepsins L, B and H in the tenderization process. This study provides further insights into the tenderization process of yak meat, which may ultimately be used for the advantageous manipulation of the process.