不同多糖对冻藏过程中草鱼肌原纤维蛋白流变性的影响

Effect of Different Polysaccharides on the Rheology of Grass Carp Myofibrillar Proteins during Frozen Storage

以草鱼肌原纤维蛋白作为研究对象,添加魔芋葡甘聚糖降解产物及葡聚糖(7 000 D,T7),测定草鱼肌原纤维蛋白质量浓度、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)和流变性质的变化,比较不同多糖对冻藏过程中肌原纤维蛋白的冷冻保护效果,探讨不同多糖对草鱼肌原纤维蛋白结构的冷冻保护机制。研究发现,随冻藏时间的延长,空白、酶解魔芋葡甘聚糖、辐解魔芋葡甘聚糖、T7及商业抗冻剂各组对应草鱼肌原纤维蛋白质量浓度和流变储能模量(G’)均下降,与冻藏过程草鱼肌原纤维蛋白SDS-PAGE的变化基本吻合。同时,添加上述不同多糖各组草鱼肌原纤维蛋白质量浓度和G’均高于空白组。研究结果表明:T7、酶解魔芋葡甘聚糖及辐解魔芋葡甘聚糖通过保护副肌球蛋白和肌球蛋白轻链,延缓草鱼肌原纤维蛋白的变性,其中,辐解魔芋葡甘聚糖效果最强,T7次之,酶解魔芋葡甘聚糖最弱,但都具有明显的冷冻保护作用。

The study aimed to investigate the cryoprotective effect and mechanism of different polysaccharides on grass carp myofibrillar protein during frozen storage. Grass carp myofibrillar proteins added with 0.5% β-glucanase konjac glucomannan（KGM） hydrolysate, 0.5% irradiation degraded KGM and 0.5% dextran, respectively, were stored at-18 ℃ for 0, 10 d and 75 d. Changes in myofibrillar protein concentration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE） pattern and rheology were measured. Results showed that the concentration and storage modulus（G＇） of grass carp myofibrillar protein added with nothing, β-glucanase KGM hydrolysate, irradiation degraded KGM, dextran T7 and a commercial antifreeze decreased with frozen storage time, which was in accordance with the changes in SDS-PAGE pattern during frozen storage. At the same time, the concentration and storage modulus（G＇） of grass carp myofibrillar protein added with different polysaccharides were higher than those of the control. It was demonstrated that the cryoprotection of β-glucanase KGM hydrolysate, irradiated degraded KGM and dextran on grass carp myofibrillar proteins was achieved by protecting the alpha helix structure of vice myosin and myosin light chain. The cryoprotection of different polysaccharides was in the decreasing order： irradiation degraded KGM 〉dextran T7〉 β-glucanase KGM hydrolysate.