物料含水率对大豆蛋白挤压产品组织化质量的影响

【目的】探讨水分对大豆蛋白挤压产品组织化质量的影响,为大豆蛋白模拟肉产品的挤压生产提供理论指导。【方法】物料含水率28%—60%的大豆分离蛋白(SPI)经DSE-25实验型双螺杆挤压机加工,分析挤压产品在8种不同缓冲液中(即磷酸缓冲液(P)、P+SDS(S)、P+尿素(U)、P+巯基乙醇(M)、P+S+U、P+U+M、P+M+S、P+S+U+M)的溶解度,进而分析蛋白质的化学交联情况,采用SDS-PAGE凝胶电泳分析蛋白质的分子量分布和聚合程度,通过组织化度测定和电镜扫描观察反映挤压产品的组织化质量情况。【结果】随着物料含水率增加,大豆蛋白挤压产品在P中的溶解度显著降低(P0.05),在P+S+M和P+M+U中的溶解度显著升高(P0.05),蛋白质分子的聚合程度降低了,挤压产品中出现纤维状和多孔状结构,组织化度增大。【结论】增加物料含水率有利于挤压产品中二硫键与氢键、二硫键与疏水作用之间协同作用的形成和蛋白质的伸展变性,大大降低了蛋白质分子的聚合程度,从而大大提高了挤压产品的组织化质量。

Effect of Moisture Content on Quality of Texturization of Product Extruded from Soy Protein Isolate

Objective]The effect of feed moisture content on quality of texturization of extruded soybean protein was investigated in order to provide a theoretical basis for producing of textured meat analogue by extrusion technology.Method]Soybean protein isolate(SPI)with moisture content at 28%-60% were processed using a DSE-25 pilot-scale twin-screw extruder.The protein solubility of both raw material and extrudates from various treatments were analyzed based on 8 different buffer solutions, which contained only phosphate(P); two reagents, i.e.sodium dodecyl sulfate(P+S), urea(P+U)and 2-mercaptoethanol (P+M); three reagents, i.e.(P+S+U),(P+U+M)and(P+M+S); four reagents, i.e.(P+S+U+M).The chemical cross-linkage of textured soybean protein was further analyzed based on the solubility.The distribution of molecular weight and degree of polymerization were investigated by using SDS-PAGE electrophoresis.The quality of texturization of extrudate from soybean protein was characterized by degree of texturization measurement and scanning electronic microscopy(SEM).Result]With moisture content increasing, the solubility of extrudates in P decreased significantly(P＜0.05), the solubility in P+S+M and P+M+U increased dramatically(P＜0.05), the degree of forming macromolecule polymer decreased, the fibrous and porous structure in extrudate appeared, and the degree of texturization increased significantly.Conclusion]Increasing moisture content could promote the alignment of soybean globulin, increase the interactions between disulfide bonds and hydrogen bond, disulfide bonds and hydrophobic bonds dramatically,decrease the degree of polymerization, further enhance the quality of texturization in extruded soybean protein.