贮藏期UHT奶中蛋白质组成结构及其糖基化的变化

通过测定UHT奶在贮藏过程中蛋白水解,蛋白在胶束相和乳清相的分布,乳蛋白糖基化位点变化,探究乳蛋白在贮藏过程中性质的变化.结果表明贮藏过程中UHT奶中菌落总数增大,纤溶酶含量增大.UHT奶在内外源酶的作用下乳蛋白发生不同程度的水解.热处理导致从胶束表面脱落的κ-CN和乳清蛋白以热诱导聚合物的形式,在贮藏过程中重新结合到...

Changes in Protein Interactions and Modifications in UHT Milk During Storage

Thermal processing of liquid milk is needed to control bacteria levels in dairy products and ensure food safety.Heating induces changes in milk protein structures and consequently alters the way that proteins interact at the molecular and colloidal levels.We investigated protein modifications that occur during long-term storage of raw and ultra-high temperature processed(UHT)milks.Although casein dissociation and whey protein/κ-casein association were found in UHT milk,the level of protein interactions was more pronounced in UHT milk after storage.The amounts ofκ-casein(κ-CN)andβ-lactoglobulin(β-lg)increased gradually in the micelle phase during the storage suggesting that re-association ofβ-lg/κ-CN complexes with the micelles,resulting in an increase in casein micelle size during storage.The early stage Maillard products(lactulosyllysine and CML)were found in UHT-treated milk,with the levels of these products maintained and generally increased with increasing storage time.This work seeks to provide a better understanding of the changes that occur in proteins in UHT milk and its potential implications on milk nutritional quality.