MECHANICAL AND STRUCTURAL CHARACTERISTICS OF SINGLE MUSCLE-FIBERS ANDFIBER GROUPS FROM RAW AND COOKED PORK LONGISSIMUS MUSCLE

The aim of this study was to analyse the mechanisms that determine why small groups of muscle fibres may have different mechanical propertie s than single muscle fibres. The method used combined light microscopy and tensile testing on single fibres and small groups of fibres from raw and cooked (80 degrees C) meat, from both conditioned and uncondit ioned porcine longissimus muscle. The results skewed that small groups of fibres had different breaking properties than constituent single f ibres in raw muscle, but that these differences diminished on cooking. Raw groups of fibres showed a more uniform lengthening along their en tire length and a higher extension to rupture than single fibres. Cond itioning increased maximum strains in both single fibres and small fib re groups. In unconditioned cooked meat, single fibres and fibre group s showed comparable breaking stresses and extensions. Conditioning res ulted in a lower strength in fibre groups than in single fibres. These results show that (endomysial) connective tissue linkages between adj acent muscle fibres in a small group significantly alter the breaking behaviour of single fibres. The effects of these connective tissue lin kages are not reduced by conditioning alone, but are largely diminishe d by cooking to 80 degrees C. (C) 1997 Elsevier Science Ltd.