Purslow P P, Oiseth S, Hughes J, Warner R D
Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Argentina.
CSIRO Food and Nutrition, 671 Sneydes Road, Werribee, Victoria 3030, Australia.
Food Res Int. 2016 Nov;89(Pt 1):739-748. doi: 10.1016/j.foodres.2016.09.010. Epub 2016 Sep 29.
Meat loses fluid during cooking, resulting in textural changes and loss in cook yield. To understand the structural basis of cooking losses, this work used 10 bovine semitendinosus muscles and two ageing periods (1 vs 14days) to examine micro- and macro-level dimensional changes in muscle during heating. Muscle blocks, muscle fibre fragments and myofibrils all showed similar maximum shrinkage in cross sectional area (20-24%) but maximum length shrinkage was less in myofibrils (15%) than muscle blocks and fibre fragments (25%). Dimensional changes were dominated by shrinkage in individual muscle fibres and myofibrils, indicating that connective tissue does not play a major role. Transverse shrinkage predominantly occurred over 50-65°C whereas the longitudinal shrinkage predominantly occurred over 70-75°C; we attribute these two separate shrinkage events to denaturation of myosin and actin respectively. Higher cook losses in samples aged for 14days versus 1day suggests that desmin, nebulin and titin denaturation are not major drivers of fluid expulsion as these proteins are degraded during ageing. We postulate that proteolysis during ageing produces protein fragments which are more easily lost from the structure during cooking, along with water.
肉类在烹饪过程中会失去水分，导致质地变化和烹饪产量损失。为了了解烹饪损失的结构基础，本研究使用了10块牛半腱肌和两个老化期（1天和14天）来研究加热过程中肌肉在微观和宏观层面的尺寸变化。肌肉块、肌纤维片段和肌原纤维的横截面积最大收缩率相似（20%-24%），但肌原纤维的最大长度收缩率（15%）低于肌肉块和纤维片段（25%）。尺寸变化主要由单个肌纤维和肌原纤维的收缩引起，这表明结缔组织不起主要作用。横向收缩主要发生在50-65°C，而纵向收缩主要发生在70-75°C；我们将这两个独立的收缩事件分别归因于肌球蛋白和肌动蛋白的变性。与1天龄的样品相比，14天龄的样品烹饪损失更高，这表明结蛋白、伴肌动蛋白和肌联蛋白的变性不是液体排出的主要驱动因素，因为这些蛋白质在老化过程中会降解。我们推测，老化过程中的蛋白水解会产生蛋白质片段，这些片段在烹饪过程中更容易与水一起从结构中流失。
