多糖对罗非鱼鱼糜凝胶化行为的影响

Effect of Polysaccharides on Gelation Behavior of Tilapia Surimi

为了改善未漂洗鱼糜凝胶强度差、易劣化等问题,分析不同添加量的卡拉胶、魔芋胶和壳聚糖3种离子型多糖对罗非鱼未漂洗鱼糜凝胶的物性学、低场核磁共振、流变学、显微成像等的影响。结果表明:在白度方面,与空白相比(47.81),添加不同多糖(卡拉胶、壳聚糖、魔芋胶)后白度最大值依次为93.07,80.88,73.95,卡拉胶效果最佳,且3种多糖添加量均在1%时白度值最大。与空白相比(88.18%),添加1%卡拉胶后持水性最高(92.51%)。低场核磁共振中T22弛豫峰峰面积结果显示,卡拉胶的不易流动水含量较高,表明其凝胶网络更致密、有序。在质构方面,与未加多糖的空白组相比,添加卡拉胶能够显著增加鱼糜硬度(P<0.05),当添加量分别为0.5%,1%,2%时,硬度分别增加了155.44,1 168.21,2 252.2 g;咀嚼性依次增加了93.53,700.99,1 108.22,且研究表明多糖添加量≥1%时,能显著提高鱼糜质构特性。在凝胶强度方面,卡拉胶的凝胶强度表现出较大的提升,并且与空白组样品(1 585.54 g·mm)的凝胶强度相比,添加量为2%时鱼糜凝胶达到3 765.35 g·mm。流变学特性表明:在恒温阶段,3种多糖均可提高鱼糜凝胶的储能模量(G’)。蛋白质二级结构表明添加卡拉胶和壳聚糖可以改变鱼糜蛋白的构象。通过伊红染色微观观察得出,随着多糖添加量的增加,多糖相呈现的区域越来越大,3种多糖中添加卡拉胶的蛋白相区域鱼糜凝胶微观结构较致密。电泳图谱表明卡拉胶的添加并未引起条带颜色的变化,推测多糖在鱼糜凝胶中主要起填充作用。综上所述,添加卡拉胶更有利于促进罗非鱼鱼糜凝胶网络的形成,改善其凝胶品质。

In order to improve the poor strength and deterioration of the unrinsed surimi gel,the effects of three different ionic polysaccharides,including carragenan,konjac gum and chitosan,on the physical properties,low-field NMR,rheology and microscopic imaging of the unrinsed surimi gel of tilapia were analyzed.The results showed that,compared with the blank(47.81),the maximum whiteness values of different polysaccharides(carrageenan,chitosan,konjac gum)were 93.07,80.88 and 73.95,indicating that the improvement effect of carrageenan was the best,and the whiteness values of the three polysaccharides were the maximum when the addition amount of all three polysaccharides was 1%.The results of water retention showed that:compared with the blank(88.18%),the water retention of 1% carrageenan was the highest(92.51%).The T22relaxation peak area in low-field NMR indicated that the content of unmobile water in carrageenan was higher,indicating that the gel network was more compact and ordered.In terms of texture,carrageenan supplementation significantly increased the hardness of surimi compared with the blank group without polysaccharide(P<0.05),the hardness increased by 155.44,1 168.21 g and 2 252.2 g at 0.5%,1% and 2%,respectively.The masticability was increased by 93.53,700.99 and 1 108.22,respectively,and the results showed that the content of polysaccharide ≥1% could significantly improve the texture characteristics of surimi.In terms of gel strength,the gel strength of carrageenan showed great improvement,and compared with the gel strength of the blank group sample(1 585.54 g·mm),the gel strength of 2% surimi gel reached 3 765.35 g·mm.Rheological properties showed that all three polysaccharides could increase the energy storage modulus(G’) of surimi gel at constant temperature.The protein secondary structure showed that the conformation of surimi protein was changed by adding carrageenan and chitosan.Microscopic observation of eosin staining showed that with the increase of polysaccharide content,the region of polysaccharide phase became larger and larger,and the microstructure of surimi gel in the protein phase region of carrageenan added among the three polysaccharides was dense.The electrophoretic map showed that the addition of carrageenan did not change the color of the bands,and it was speculated that polysaccharide played a main role in filling the surimi gel.In conclusion,the addition of carrageenan is more beneficial to promote the formation of gel network and improve the gel quality of tilapia surimi.