【作者】 李汴生；

【导师】 彭志英；

【作者基本信息】 华南理工大学 ， 食品工程， 1997， 博士

【摘要】 超高压处理技术是一种新型的食品加工和保藏技术，作为这一技术应用的基础，人们不仅要了解超高压处理对食品中微生物和酶的影响，而且应知道超高压处理后食品有关特性的变化。蛋白质和多糖是食品的两类主要成分，并体现出重要的功能特性。本文以豆浆，大豆分离蛋白、乳粉、明胶等蛋白质胶体和卡拉胶、琼胶、果胶等多糖胶体为对象，在≤500MPa、常温、0～30min的条件下，研究超高压处理后胶体有关理化性质的变化，以认识和总结其规律。 结果表明：豆浆的浊度在＞200MPa压力处理后略有下降，但沉降稳定性和热稳定性均提高，油脂、pH和糖分对这种变化有影响。超高压处理使得大豆分离蛋白的溶解性明显改善。扫描电镜的观察显示，压力处理后豆浆和大豆分离蛋白中的蛋白质颗粒的粒径下降，而脂肪球增大。超高压处理后，豆浆和大豆分离蛋白溶液的粘度增加，这主要是蛋白质颗粒降解、浓度增加所致；乳粉溶液处理后也有类似的变化。超高压处理后大豆蛋白溶液的粘弹性也相对提高，其中豆浆的弹性在≤200MPa增加，之后降低。对蛋白质结构的化学分析和红外扫描分析表明，≤400MPa超高压处理后，蛋白质分子发生降解、伸展，二硫键部分断裂，内部疏水基团外露，使其巯基含量和相对疏水性均增大，蛋白质的表面性质和形成凝胶的能力加强，所形成的凝胶细腻、持水性高，凝胶强度略低，但明胶凝胶处理后强度有所提高；电泳的结果还显示，500MPa的压力导致大豆蛋白部分凝聚。 分子量大，在溶液中呈一定卷曲状态的多糖胶体，超高压处理后由于分子结构的伸展，极性基团外露，使其电荷量和溶剂化作用增强，溶液的粘度更多还原

【Abstract】 Ultrahigh pressure (UHP) treatment is a new technology for food processing and storage. As the base of the application of this technology, we should not only to understand the effects of UHP treatment on microorganisms, enzymes in food, but also to know the changes of foods’ physicochemical properties after the treatment. Protein and polysaccharide are two main components of foods, and they have important functional properties. In this dissertation, protein colloid solutions of soybean milk, isolated soybean protein (ISP), milk powders and gelatin, polysaccharide colloid solutions of carrageenin, agar, high methoxyi pectin, etc. were used as research objects, at the condition of ≤ 500MPa pressure, normal temperature, 0~30min, to study the changes of physicochemical properties after the UHP treatment.The results showed that the turbility of soybean milk slightly decreased after the treatment of pressure more than 200MPa, but its settling stability and heat stability increased, oil or fat, pH and sugar affected the changes. UHP treatment greatly improved the solubility of ISP. The results of SEM observation showed that the particle size of protein in soybean milk and ISP solution decreased, and that of fat in soybean milk increased after UHP treatment. The viscosity of soybean milk and ISP solution increased as the result of decreasing of particle size and increasing concentration of protein particles. Solutions of bovine milk powder had similar changes after the treatment. The elasticity of the solutions also increased, but when the pressure was ≥ 200MPa, the elasticity of soybean milk decreased. The chemical analysis and infrared absorption spectrum of the solutions displayed that the protein disassociated and unfolded with the treatment of ≤ 400MPa, disulphar bonds were partially disrupted, and the internal hydrophobic groups demasked. These made the contents of -SH groups and hydrophobicity increasing, which improved the proteins’ surface properties and ability for gelatification, and formed gel was fine and with a high water holding capacity, lower gel strength. The gel strength更多还原