本文探究了酸预处理时间对鲢鱼皮明胶理化性质的影响。结果发现，当酸预处理时间从10 min增加到80 min，鲢鱼皮的结构变得疏松，在热水浸提中β肽链等胶原高分子组分易发生降解，提取的明胶其羟脯氨酸含量从61个残基下降到43个残基/1000个氨基酸。不管酸预处理时间多长，提取的鲢鱼皮明胶其等电点均在pH 9.2附近，但长时间的酸处理会使明胶的黏度、凝胶性能和成膜性能下降。当酸预处理时间为10 min时，制备的明胶凝胶强度、膜的抗拉伸强度和断裂延伸率分别为242.67 g、28.24 MPa和65.52%。根据圆二色光谱扫描的结果，发现酸预处理时间对明胶二级结构没有明显的影响，但酸预处理时间越长，提取的明胶在干燥过程中越不易复性形成三股螺旋结构，结果导致成膜性能下降。

In this study, the effect of acid pretreatment duration on the physicochemical properties of gelatin from silver carp skins was investigated. The results showed that when the acid pretreatment time was increased from 10 to 80 min, the structure of silver carp skin was loosened; the high molecular weight fractions of collagen, including the β-chain, were susceptible to degradation during the hot-water extraction. The hydroxyproline content of the extracted gelatin was decreased from 61 to 43 residues per 1000 amino acid residues. The isoelectric point of gelatin from silver carp skins was approximately at pH 9.2, regardless of the duration of acid pretreatment. However, viscosity, gel properties, and film-forming ability of extracted gelatin were decreased after long acid pretreatment. When the acid pretreatment time was 10 min, the strength of prepared gelatin gel, the tensile strength, and the elongation at break of the prepared gelatin gel were 242.67 g, 28.24 MPa, and 65.52%, respectively. Based on circular dichroic analysis, the acid pretreatment time had no significant effect on the secondary structure of extracted gelatin. However, the longer the acid pretreatment time, the more difficult it became to form triple helical structures through renaturation route in the drying process of the gelatin solution, resulting in a decrease in film-forming ability.

福建省杰出青年科学基金项目(2014J06013)；国家自然科学基金(31271984)；厦门市海洋经济发展专项资金(14CZP031HJ05）