基于人体必需金属盐替代的低钠盐肌原纤维蛋白凝胶特性和作用机理

Characterization of Low-Sodium Myofibrillar Protein Gels with Substitution of Human Essential Metal Salts and Their Mechanisms of Action

为降低肌原纤维蛋白凝胶中钠盐的使用量,研究不同氯盐(CaCl_(2)、MgCl_(2)、KCl)部分替代NaCl对肌原纤维蛋白凝胶性质包括强度、微观结构、持水力和流变学性质的影响,并通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、内源性荧光光谱、表面疏水性、巯基含量等技术手段阐明其作用机理。结果表明,3种氯盐替代效果排序为KCl>CaCl_(2)>MgCl_(2)。0.5%~1.5%质量分数的盐替代范围内,KCl替代组的凝胶强度优于对照组(3%NaCl),持水力与对照组相比无显著差异(P>0.05);CaCl_(2)替代组的凝胶强度在1.5%替代质量分数时显著下降(P<0.05),持水力呈先下降后上升趋势;MgCl_(2)替代组凝胶强度显著降低(P<0.05),持水力上升。在流变学性质方面,不同质量分数KCl替代组的储能模量明显高于对照组。CaCl_(2)和MgCl_(2)的替代使肌原纤维蛋白表面疏水性增大、巯基含量减少,3种氯盐的替代使内源性荧光光谱均出现蓝移现象。CaCl_(2)、MgCl_(2)和KCl以低质量分数(0.5%)替代时,肌原纤维蛋白凝胶的微观结构与对照组无明显差异。以上结果表明CaCl_(2)、MgCl_(2)和KCl部分替代NaCl可有效降低鱼糜凝胶产品中的钠盐含量。

In order to reduce the amount of added sodium in myofibrillar protein(MP)gel,the effects of partial substitution of different chloride salts(CaCl_(2),MgCl_(2),and KCl)for NaCl on the gel strength,microstructure,water-holding capacity and rheological properties of MP gel were studied.The underlying mechanism of action of sodium substitutes was elucidated by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and intrinsic fluorescence spectroscopy as well as measuring surface hydrophobicity and sulfhydryl content.The results showed that KCl was the best substitute for NaCl,followed by CaCl_(2),and MgCl_(2) was least effective in replacing NaCl.The gel strength of the KCl substitution groups(0.5%KCl+2.5%NaCl,1.5%KCl+1.5%NaCl,and 1.0%KCl+2.0%NaCl;m/m)was better than that of the control group(3%NaCl),while no significant difference in water-holding capacity was found between the two groups(P>0.05).The gel strength of the 1.5%CaCl_(2)+1.5%NaCl group decreased significantly(P<0.05),and the water-holding capacity decreased first and then increased.The gel strength significantly decreased(P<0.05)and the water-holding capacity increased in the MgCl_(2) substitution groups.In terms of rheological properties,the storage modulus(G’)of the KCl substitution groups was significantly higher than that of the control group.Substitution of CaCl_(2) and MgCl_(2) increased the surface hydrophobicity of MP and decreased the sulfhydryl content.Substitution of CaCl_(2),MgCl_(2),and KCl resulted in a blue shift in intrinsic fluorescence spectra.At low substitution levels(0.5%),the microstructure of MP gel showed no significant difference from that of the control group.The above results indicate that CaCl_(2),MgCl_(2) and KCl can be used to partially substitute NaCl in surimi gel products.