亚油酸介导氧化的金鲳鱼肌原纤维蛋白结构和凝胶特性变化

Changes in the Structure and Gel Properties of Golden Pomfret Myofibrillar Protein Induced by Linoleic Acid-mediated Oxidation

摘要:

该研究通过构建亚油酸介导金鲳鱼鱼肉氧化体系，探究了不同浓度的亚油酸（0、10、20、50 mmol/L）介导氧化对金鲳鱼肌原纤维蛋白凝胶强度、凝胶保水性和凝胶水分分布的影响。结果表明：亚油酸浓度为10 mmol/L时氧化对凝胶特性的影响最明显，离心损失和蒸煮损失达到最小，分别为5.39%和5.94%。凝胶强度达到最大值，为333.24 g。随着亚油酸浓度的增加，肌原纤维蛋白羰基含量从2.86 nmol/mg上升至6.65 nmol/mg，总巯基含量从63.58 nmol/mg下降为58.69 nmol/mg，从分子量变化可以发现，随着蛋白质氧化程度的增加，表面疏水性和内源荧光强度呈现先上升后降低的趋势，这表明适度的亚油酸氧化（≤10 mmol/L）可以引起蛋白质分子适度展开，形成质构特性好、保水性高的凝胶产品；而过高的亚油酸氧化（>10 mmol/L）则引起蛋白质过度氧化，导致蛋白质分子交联、聚集，从而降低蛋白质凝胶质构特性。该研究阐明亚油酸氧化对金鲳鱼后期加工特性影响，促进金鲳鱼产业发展。

Abstract:

In this study, the effects of different concentrations of linoleic acid (0, 10, 20, and 50 mmol/L) for mediating oxidation on the gel strength, gel water retention, and gel water distribution of golden pompano myofibrillar protein through constructing a linoleic acid-mediated golden pompano fish flesh oxidation system. The results showed that the effect of oxidation on the gel properties was most obvious at a linoleic acid concentration of 10 mmol/L, with the centrifugal loss and cooking loss reaching the smallest (5.39% and 5.94%, respectively), while the gel strength reaching the maximum value (333.24 g). With the increase of linoleic acid concentration, the carbonyl content of myofibrillar protein increased from 2.86 nmol/mg to 6.65 nmol/mg, and the total sulfhydryl group content decreased from 63.58 nmol/mg to 58.69 nmol/mg. The molecular weight change revealed that with the increase of the degree of protein oxidation, the surface hydrophobicity and intrinsic fluorescence intensity showed a tendency of initial increase then decrease, indicating that moderate linoleic acid oxidation (≤10 mmol/L) could cause protein molecules to unfold moderately, forming a gel product with good textural properties and high water retention; whilst excessive linoleic acid oxidation (>10 mmol/L) caused excessive oxidation of proteins, leading to cross-linking of protein molecules and aggregation of protein molecules, thereby declining the textural properties of protein gels. This study elucidates the effects of linoleic acid oxidation on the post-processing characteristics of golden pomfret and promote the development of the golden pomfret industry.