带皮牛肉酶法嫩化及保鲜新工艺研究

为了解决牛肉与牛皮产品在加工过程中的嫩化和保鲜问题,系统研究了影响木瓜蛋白酶嫩化法对牛肉和牛皮嫩化效果的因素、使牛肉和牛皮达到最佳的加工熟度的加热方法及Nisin和乳酸钠复配使用对酱卤制品的保鲜效果。结果表明：原料肉在腌渍时保持温度0-10℃,加入0．05％木瓜蛋白酶嫩化20min,嫩化效果最好,出品率也最高;煮制时添加1．9％食盐,温度95℃,煮制时间40min,加工产品熟度最佳;Nisin和乳酸钠复配的保鲜液对卤牛肉中的微生物生长有一定的抑制作用。     

影响肉质嫩度的因素以及肉质嫩化方法的探讨

肉的嫩度是受很多因素影响的。本文结合国内外对肉质嫩度的研究现状,系统地总结了影响肉质嫩度的因素并对不同因素的研究进展作了阐述,同时对目前普遍使用的肉嫩化方法作了介绍。     

内源性蛋白酶对宰后肌肉嫩化机制研究进展

 肌肉的宰后嫩化机制一直是国内外肉品科学研究的一个热点,目前认为肌肉宰后嫩度的改善主要归因于内源性水解酶作用所引起的肌原纤维蛋白的有限降解。钙激活酶虽然是宰后嫩度改善的一个主要贡献者,但不是惟一的,而是多种内源酶类协同作用的结果。本文综述了溶酶体组织蛋白酶、蛋白酶体、钙激活酶在宰后嫩化过程的作用;介绍了细胞凋亡的特点、通路及凋亡酶,并对细胞凋亡酶对宰后嫩度改善的潜在贡献进行了讨论;最后分析了细胞凋亡酶和钙激活酶在宰后成熟过程中的交互作用及共同贡献于肌肉宰后嫩化的可能性。     

宰后H2O2处理的藏羊肉能量代谢、细胞凋亡及嫩化研究

为明确宰后H_2O_2处理对欧拉藏羊肉成熟过程中能量代谢、细胞凋亡及嫩化的影响,选取欧拉藏羊背最长肌为试验材料,分别用蒸馏水和50、200 mmol/L活性氧激活剂进行过氧化氢处理,在4℃条件下成熟,测定在成熟期间(0、0.5、1、3、5、7 d) ROS相对含量、ATP含量、Ca~(2+)-ATPase活力、Na~+/K~+-ATPase活力、细胞凋亡率、肌原纤维小片化指数(MFI)与肌纤维直径的变化。结果表明,H_2O_2处理后成熟7 d时,50 mmol/L H_2O_2处理组的ROS相对含量比对照组高39.19%(P0.05);50 mmol/L H_2O_2和200 mmol/L H_2O_2处理组的ATP含量、Ca~(2+)-ATPase和Na~+/K~+-ATPase活力、肌纤维直径比对照组分别低25.73%和25.77%、38.39%和36.70%、27.30%和29.46%、13.68%和13.94%(P0.05);两个处理组的细胞凋亡率与MFI比对照组分别高63.07%、50.42%与5.74%、5.19%(P0.05)。研究表明,宰后H_2O_2处理藏羊肉,导致ROS含量增加,改变了藏羊肉能量代谢,诱导了细胞凋亡,促进了藏羊肉的嫩化。本研究可为藏羊肉品质改善提供理论参考。     

生姜蛋白酶和生姜汁对猪肉嫩化效果的比较

本文研究了生姜蛋白酶及生姜汁对猪肉的嫩化效果，对其用量、pH值、预处理温度进行了测试对比。结果表明：生姜蛋白酶及生姜汁对猪肉的嫩化效果十分显著(P≤O．01)，生姜蛋白酶最佳用量为O.01％，姜汁最佳用量5％，最佳pH都为7.O，最佳预处理温度生姜蛋白酶为300℃，生姜汁为40℃；并且生姜蛋白酶及生姜汁对猪肉的嫩化效果极为相似，可以证明，生姜汁对肉类的嫩化作用就是生姜汁中的生姜蛋白酶作用的结果。     

Structural weakening of intramuscular connective tissue during postmortem aging of pork

We studied structural changes in the endomysium and perimysium during postmortem aging of pork using the cell‐maceration/scanning electron microscope method. Immediately post mortem, endomysia sheaths that house individual muscle fibers displayed a honeycomb‐like structure. The sheaths of the endomysium consisted of tightly arranged collagen fibrils in a random network. The perimysium comprised several layers of wavy sheets made up of tightly bundled collagen fibers. While the structure of the intramuscular connective tissues remained almost unchanged up to five days post mortem, the endomysium had resolved into individual collagen fibrils, and the thick sheets of the perimysium had separated into collagen fibers and fibrils at 8 days post mortem. These results provide direct evidence for structural weakening of the endomysium and perimysium during postmortem aging of pork. The shear‐force value of raw pork decreased rapidly within six days post mortem and then decreased slowly until 14 days post mortem. Since the rapid increase in tenderness is mainly due to structural weakening of myofibrils, we conclude that the disintegration of the endomysium and perimysium contributes to tenderization of pork during extended postmortem aging.     

Relationship between beta-adrenergic agonists,calpain system activity and beef texture: A systematic review

The objective was to conduct a systematic review to evaluate the effects of dietary supplementation with beta-adrenergic agonists on calpains and calpastatin activity in bovine muscle and changes in meat tenderness. A survey was conducted in June 2019 on Science Direct, Web of Science, Scopus, PubMed and Capes Periodicals, using four keyword combinations: agonist and calpain and cattle; agonist and calpain and bovine; agonist and calpain and heifers; agonist and calpain and steers. Thirteen studies were selected, 54% concluded that supplementation with beta-adrenergic agonists increases calpastatin activity, 23% observed increase in their gene expression and 23% reported no effect on activity or expression of this enzyme. Nine studies evaluated the influence of beta-adrenergic agonists supplementation on meat texture and all found an increase in shear force values. There is strong evidence that beta-adrenergic agonists may increase calpastatin activity in the muscle, causing damage to meat tenderness.