The effects of suspension method, chilling rates and post mortem ageing period on beef quality

Summary The combined effects of ‘tenderstretch’(pelvic) suspension, slow chilling and extended post mortem ageing on beef quality in six hind quarter muscles have been investigated using young Hereford cross heifers. In M. longissimus dorsi at two days post mortem, tenderstretched fast (commercially) chilled meat was more tender than meat from normally suspended carcases. Slow chilling produced still greater tenderness in both normal and tenderstretched carcases. At seven days tenderstretched fast chilled meat had become as tender as slowly chilled meat but normally suspended fast chilled meat was not as tender, although it had undergone considerable tenderizing. These differences persisted to fourteen days post mortem without any significant increase in tenderness occurring. Sarcomere lengths were increased by tenderstretching but were not reduced by fast chilling. In M. psoas major tenderstretching produced a slight toughening and shorter sarcomeres. Slow chilling had no effect, and ageing produced a slight reduction in shearforce. In M. biceps femoris tenderstretching greatly lengthened the sarcomeres but produced only a small tenderizing effect. Slow chilling and ageing had no effect. In M. semitendinosus tenderstretching increased sarcomere lengths. A slight fall in shearforce was associated without interaction with both tenderstretching and ageing. In M. semimembranosus slow chilling had no apparent effect while tenderstretching increased sarcomere length and produced meat that was more tender at two days than meat from normally suspended sides at fourteen days. Ageing increased tenderness in both suspension treatments to about the same extent. In M. gluteus medius tenderstretch suspension produced a marked tenderizing effect which persisted to fourteen days. Ageing increased tenderness and, unlike other muscles continued to be effective between seven and fourteen days.