冻藏条件下魔芋葡甘聚糖降解产物对肌原纤维蛋白结构的影响

为了研究魔芋降解产物对肌原纤维蛋白冷冻保护的作用机制,以草鱼肌原纤维为研究对象,采用紫外光谱、傅里叶红外光谱和扫描电镜研究不同的魔芋葡甘聚糖(konjac glucomannan,KGM)降解产物对冷冻贮藏草鱼肌原纤维蛋白结构的影响。结果表明:随着贮藏时间的延长,肌原纤维蛋白的最大吸收波长呈红移,主要由酪氨酸产生,不同的冷冻保护剂均不能保护酪氨酸的暴露。α-螺旋和β-折叠为草鱼肌原纤维蛋白主要的二级结构,随着贮藏时间的延长,α-螺旋结构所占比例上升,β-折叠结构所占比例下降,β-转角和无规卷曲的含量变化不大。辐照降解KGM和酶解KGM均对草鱼肌原纤维蛋白的二级结构有保护作用,稳定α-螺旋和β-折叠所占比例;而蔗糖-山梨糖醇促进草鱼肌原纤维蛋白中α-螺旋结构形成,不利于β-转角结构。显微观察的结果显示,辐照KGM样品和酶解的KGM样品可以延缓蛋白分子的聚集,延缓蛋白出现多孔状结构,而蔗糖-山梨糖醇样品冻藏过程保持片层结构。

Effect of Degraded Products of Konjac Glucomannan on the Structure of Myofibrillar Protein from Glass Carp Meat during Frozen Storage

The present study investigated the effect of different degraded products of konjac glucomannan (KGM) on the
structure of myofibrillar protein from glass carp meat during frozen storage by ultraviolet spectroscopy, infrared spectroscopy
(IR) and scanning electronic microscope (SEM), in order to elucidate the cryoprotective mechanism of degraded products
of konjac glucomannan on myofibrillar protein. The results showed that α-helix and β-sheet were the major secondary
structures of myofibrillar protein from grass carp meat. The content of α-helix structure increased with prolonged frozen
storage, while the content of β-sheet structure decreased. And there were little changes in the contents of β-turn structure and
random coil. The degraded KGM by irradiation or β-glucanase could protect α-helix and β-sheet of myofibrillar protein from
grass carp meat and stabilize the proportions of the two secondary structures. Sucrose-sorbitol mixture could promote the
formation of α-helix structure but hinder the formation of β-turn. The microstructure of myofibrillar protein exhibited that
the degraded products of KGM from both treatments could retard the aggregation of myofibirillar protein, while the addition
of sucrose and sorbitol could result in formation of lamellar structure.