预冻与真空冷冻干燥对金线鱼肌原纤维蛋白理化性质和凝胶特性的影响

史秋艳; 林端权; 何文雄; 刘康; 张凌晶; 翁凌; 孙乐常

doi:10.13386/j.issn1002-0306.2024040160

预冻与真空冷冻干燥对金线鱼肌原纤维蛋白理化性质和凝胶特性的影响

Effects of Pre-Freezing and Vacuum Freeze-drying on Physicochemical Properties and Gelling Characteristics of Myofibrillar Protein from Nemipterus virgatus

摘要

摘要: 为研究真空冷冻干燥对鱼糜粉品质的影响，以金线鱼肌原纤维蛋白为研究对象，分别研究真空冷冻干燥的预冻处理和真空冷冻干燥对肌原纤维蛋白（myofibrillar protein, MP）理化性质的影响，并探究谷氨酰胺转氨酶（transglutaminase, TG酶）协同下肌原纤维蛋白凝胶特性的变化规律。结果显示，与未处理组相比，经预冻和真空冷冻干燥处理后的肌原纤维蛋白浊度和粒径显著增加（P<0.05），溶解度分别降低32.3%和42.0%，表明蛋白质在处理过程中出现聚集变性；总巯基含量分别降低17.3%和41.9%，羰基含量分别增加112.2%和181.5%，证实其发生氧化变性；α-螺旋结构含量降低和最大内源荧光强度下降（从4903下降到4789、1425），揭示蛋白质有序结构遭到破坏和微环境发生改变。肌原纤维蛋白经预冻处理与真空干燥处理均导致储能模量G′下降，其中真空冷冻干燥组的G′值最小，但添加TG酶可以在一定程度上提高G′值；凝胶微观结构显示，未处理组的凝胶微观网状结构清晰，而预冻组和真空冷冻干燥组的凝胶结构变得不均匀或未见明显凝胶网状结构，添加TG酶则促使肌原纤维蛋白凝胶网状结构变得致密均匀。综上可知，真空冷冻干燥处理中的预冻阶段与干燥阶段均会对肌原纤维蛋白理化性质和凝胶特性造成影响，其中预冻阶段引起的冷冻变性对蛋白聚集和氧化影响更大，而干燥阶段的脱水变性则对蛋白结构造成更大影响，TG酶可以提升经预冻和真空冷冻干燥之后的肌原纤维蛋白凝胶特性。

Abstract: To investigate the effects of pre-freezing and vacuum freeze-drying on the properties of frozen surimi powder, myofibrillar protein (MP) from Nemipterus virgatus was taken as the research object. The changes of physicochemical properties of MP during the processes of pre-freezing and vacuum freeze-drying, and the effect of transglutaminase (TGase) on the gelling characteristics of MP were investigated. The results showed that compared with the untreated group, the turbidity and particle size of MP treated by pre-freezing and vacuum freeze-drying increased significantly (P<0.05) with the decreased solubility by 32.3% and 42.0%, indicating that proteins aggregation occurred during the processing. The decreased total sulfhydryl content by 17.3% and 41.9%, and the increased carbonyl content by 112.2% and 181.5%, respectively, showing that oxidative denaturation occurred. The content of α-helix structure decreased and the maximum endogenous fluorescence intensity of MP treated by pre-freezing and vacuum freeze-drying decreased from 4903 to 4789 and 1425, respectively, revealing that the ordered structure of protein was destroyed and the microenvironment was changed. The gels prepared by the untreated group had the highest storage modulus G′ value, followed by the pre-freezing treatment group and then the vacuum freeze-drying group. The addition of TGase could improve the rheological properties of MP. The gel network structure of MP was clearly visible in the untreated group, and the uneven network structure appeared in the pre-freezing group, while the vacuum freeze-drying group could not form gel network structure. The addition of TGase promoted the formation of denser and more uniform gel network structure of MP. In summary, the pre-freezing stage and the drying stage in the vacuum freeze-drying could affect the physicochemical properties and gelling characteristics of MP, in which the freezing denaturation of MP caused by the pre-freezing treatment had a significant impact on the aggregation and oxidation of MP, while the dehydration denaturation of MP during the drying phase had a more pronounced effect on the structure of MP. Furthermore, the addition of TGase could improve the gelling characteristics of MP after the pre-freezing and vacuum freeze-drying treatments.