The effect of ultra-rapid chilling and subsequent ageing on the calpain/calpastatin system and myofibrillar degradation in lamb M. longissimus thoracis et lumborum

The effect of ultra-rapid chilling (-20 degreesC) on the proteolytic degrad ation of myofibrillar proteins during ageing, by the calpain/calpastatin sy stem in lamb was investigated. Carcasses (36) were ultra-rapidly chilled (- 20'degreesC for 3.5 h followed by 20.5 h at + 4 degreesC) or chilling at 4 degreesC for 24 h. After chilling all carcasses were stored at + 4 degree sC for a further 4 days. Samples of M. longissimus thoracis et lumborum wer e taken for Warner-Bratzler shear force measurement, sarcomere length, SDS- PAGE and enzyme activity analysis. Ultra-rapid chilling (-20 degreesC) had no effect on the proteolytic degradation of myofibrillar proteins by the ca lpain/calpastatin system compared to conventional chilling (+ 4 degreesC). However, no difference in tenderness was found between the two chilling reg imes at 1 or 5 days postmortem so differences in myofibrillar degradation o r enzyme activity would not be expected. (C) 2001 Elsevier Science Ltd. All rights reserved.