利用高效液相色谱-串联质谱追踪酸奶发酵过程中的酪蛋白磷酸肽

酪蛋白磷酸肽(CPPs)是酪蛋白被磷酸化的片段,具有促进矿物元素吸收、抗氧化、预防龋齿等多种生物功能。该文利用高效液相色谱-串联质谱研究牛奶经嗜热链球菌(Streptococcus thermophilus)和保加利亚乳杆菌(Lactobacillus debrueckii subsp.bulgaricus)发酵后CPPs的释放规律。结果表明,在内源性蛋白酶的作用下牛奶含内源性CPPs,内源性CPPs主要来源于高丰度酪蛋白αs1-CN和β-CN。经乳酸菌发酵后,在乳酸菌蛋白酶的作用下更多酪蛋白的磷酸化位点暴露而产生大量CPPs,其中含SpSpSpEE特征结构的CPPs也在酸奶中检测到,CPPs的释放与酪蛋白结构密切相关。研究结果表明,牛奶经乳酸菌发酵后释放大量含特征结构SpSpSpEE的CPPs,可提高结合矿物元素的能力,从而增强其促进人体健康的生物功能。

Tracking casein phosphopeptides during fermentation by high performance liquid chromatography-tandem mass spectrometry

Casein phosphopeptides (CPPs) are phosphorylated fragments of casein, which have a variety of biological functions such as promotion of mineral absorption, antioxidation and prevention of dental caries. This study investigated CPPs in milk and yogurt fermented by Lb. bulgaricus (Lactobacillus debrueckii subsp. bulgaricus) and S. thermophilus (Streptococcus thermophilus) with high performance liquid chromatography-tandem mass spectrometry. The results showed that milk contained endogenous CPPs, which were mainly derived from high abundance of caseins α_s1-CN and β-CN, in the role of endogenous protease. After milk fermented with Lb. bulgaricus and S. thermophilus, more CPPs and phosphorylation sites were released in the action of lactic acid bacteria proteases. The CPPs with the character of SpSpSpEE were identified in yogurt. The structure of caseins played an important role in CPPs releasing in the process of fermentation. In conclusion, fermentation by lactic acid bacteria is helpful to release CPPs containing SpSpSpEE, which can promote mineral absorption.