热处理对肉类蛋白质构的影响

Effect of Heat Treatments on the Protein Structures and Meat Textural Properties

加热作为最传统的肉熟化和杀菌手段,在今后的水产及畜禽肉加工产业中将依旧占主导地位。作者简述了肌肉蛋白的组成和结构,讨论了不同来源肌肉蛋白在加热过程中的变性行为。水生及陆生来源的肌肉中,大部分肌浆蛋白在40℃~60℃之间聚集,但对一些肌浆蛋白来说,加热到90℃才凝固。溶液中肌原纤维蛋白在30℃~32℃开始展开,在36℃~40℃蛋白质—蛋白质开始结合,在45℃~50℃产生凝胶化(conc.>0.5重量%)。在53℃~63℃的温度下,胶原蛋白开始变性,随后胶原纤维发生收缩。如果胶原纤维不能通过耐热分子间键稳定,则它在进一步加热时溶解并形成胶状。此外,作者还概述了不同种类肌肉蛋白在加热过程中的结构变化及其对质地品质的影响。对于一般完整肌肉的肉块,一定温度的热处理后,显微组织收缩,肌节长度缩短,持水性降低,韧性发生1次或者2次的跃升。鱼糜制品、汉堡肉饼及乳化香肠等碎肉产品,因加工工艺影响,肌肉系统的结构大幅改变。鱼糜制品形成过程较畜禽肌肉复杂;鱼类肌肉中盐溶性蛋白在加热作用下通过分子间二硫键、疏水作用力、氢键等等的作用,包裹水分重新形成立体网状结构,成为具有凝胶特性的鱼糜制品。通常畜禽类肌肉没有鱼糜凝胶形成的能力强。与乳化香肠相比,汉堡肉整体纤维和纤维碎片的出现率更高,其含量高达50%~70%,导致受热后收缩程度更大。乳化香肠中,因肌肉彻底粉碎搅拌因而肌原纤维蛋白被抽提出,在加热时产生密集的蛋白质网络—凝胶,通过毛细管作用力可有效地保持水分。了解不同种类肉蛋白质在烹饪过程中的结构变化以及质构品质变化机理,可为制定更合理的肉类加工方式提供理论依据。

Heat treatment is the leading and most traditional means of cooking and sterilizing meats from aquatic products and poultry product for the processing industry. The meat protein composition and structures are briefly described in this manuscript and the denaturing of the different proteins during the heat treatments are discussed. Most of the sarcoplasmic proteins either from aquatic or poultry meat aggregate between 40℃ and 60℃, but some coagulation can occur at up to 90℃. The unfolding of myofibrillar proteins in solution begins at 30℃~32℃, followed by protein-protein associations at 36℃~40℃, and subsequent gelation at 45℃~50℃(conc.>0.5% by weight). At temperatures between 53℃ and 63℃, collagen denaturation occurs, followed by collagen fibre shrinkage. If the collagen fibres are not stabilised by heat-resistant intermolecular bonds, they dissolve and form gelatine on further heating. In addition, the structural changes and quality changes of different kinds of meat due to the heat treatment are discussed. In most cases, after meat is heated to a certain temperature, its microscopic structure shrinks, the sarcomere length shortens, the water holding capacity decreases, and the shear force which represents hardness rises once or twice. Minced meat products including surimi products, hamburger patties and emulsified sausages have disordered muscle system structures due to the effect of heat processing. Compared with emulsified sausage, hamburger patties have a higher occurrence rate of whole fiber and fiber fragments, and their content is as high as 50%~70%, and resulting in greater shrinkage after heating. Compared to poultry product, surimi products showed to be much more complicated. Salt soluble proteins in fish muscle would reform a cubic network containing water when it was heated to be surimi products due to the formation of disulfide bridge, hydrophobic interaction and hydrogen bond, etc. In emulsified sausage, the myofibrillar protein is extracted due to the crushing and stirring of muscle, resulting in a dense protein network gel during heat treatments, and water can be effectively maintained through capillary force. Understanding the structural changes of different meat proteins and the mechanism of quality changes during heat treatments can provide a theoretical basis for formulating a more reasonable meat processing methods.