脱脂花生粉特性对其挤压产品结构的影响

Effects of Defatted Peanut Flour Property on Structure of Extruded Product

以低温脱脂花生粉为原料，采用DSE-25型双螺杆挤压实验室工作站，在花生粉高水分挤压组织化工艺优化的基础上，研究了原料特性（粒度、pH值和油脂含量）对挤压组织化产品结构的影响规律。结果表明，原料特性对脱脂花生粉挤压组织化产品的质量和结构有明显影响。粒径在0．2～0．3mm范围内的原料，其挤压产品既可保持适当的硬度和咀嚼度，又有较好的组织化结构，其微观结构细致，气腔小且分布均匀。原料的pH值对产品的流变学性质和微观结构影响较大；在花生蛋白等电点附近（pH值4．5），挤压产品的硬度和咀嚼度最高，具有较致密的组织结构；在接近中性时，组织化度最高；偏碱性条件不利于产品组织化结构的形成。随原料中油脂含量的增加，挤压产品的硬度、咀嚼度和剪切力均明显下降，扭矩显著降低；综合挤压产品的感官质量和质构分析结果，认为原料中油脂含量在3％-6％范围内，有利于挤压产品组织结构的改善和感官质量的提高。

Effects of peanut flour property, such as particle size, pH value, and fat content, on the rheological property and microstructure of textured peanut product were investigated with texture analyzer and scanning electron microscope. The peanut flour was extruded by DSE -25 twin - screw extrusion lab station under the optimal parameters. The results indicate that the structure and quality of the extrudate are affected significantly by the material property. Proper hardness, chewiness and good textured structure of the extrudate could be attained when the particle size of the peanut flour is in the range of 0.2mm to 0.3mm. Significant differences are found in the rehological property and microstructure among the extrudates with different pH value. The extrude has the highest hardness, chewiness, and very compact fibrous structure at pH 4.5 which is near the isoelectric point of peanut protein; near neutral pH value leads an extrudate of highly textured structure, and alkaline pH value is harmful to the extrudate texture. Moreover, with increasing fat content of the peanut flour, the hardness, chewiness, and shear force of the extrudate decrease greatly, and the torque of extruder drops sharply. Combined the sensory quality and textural profiles results of the extrudate, it can be concluded that the product quality would be improved when the fat content of the defatted peanut flour is 3% -6%.