乳蛋白浓缩物的酶法脱磷酸化及模拟婴幼儿体外消化性研究

Study on Enzymatic Dephosphorylation of Milk Protein Concentrate and Its Digestibility in vitro Infant

牛乳酪蛋白是婴幼儿配方乳粉的主要蛋白质组分之一,由于其磷酸化水平高于人乳酪蛋白,限制了其在婴幼儿食品中的应用。为了使牛乳酪蛋白在分子水平上更接近人乳酪蛋白,作者以乳蛋白浓缩物(MPC)为研究对象,采用马铃薯酸性磷酸酶(PAP)对MPC进行脱磷酸化修饰处理,制得了一系列具有不同脱磷酸化程度的MPC。同时利用尿素-聚丙烯酰胺凝胶电泳(Urea-PAGE)、微波消解-紫外可见吸收光谱和超高效液相串联质谱(UPLC-MS)鉴定了MPC的脱磷酸化程度,考察了脱磷酸化程度对MPC在模拟婴幼儿胃液和肠液中消化性的影响。研究结果表明,经PAP脱磷酸化修饰后,MPC中酪蛋白磷酸基团脱除率的可控范围为0~85.8%,酪蛋白脱磷酸化程度越高,其在胃液中形成的絮凝结构越疏松,且在模拟婴幼儿胃液和肠液中的消化性越好。

Bovine casein is one of the main protein components of infant formula milk powder.Its phosphorylation level is higher than that of human casein,which limits its direct application in infant foods.In order to make bovine casein closer to human casein at the molecular level,the author considered milk protein concentrate(MPC)as the research object.A series of MPCs with different dephosphorylation degrees were prepared by using potato acid phosphatase(PAP)as the dephosphorylation modification treatment.Urea-PAGE,microwave digestion-UV/visible absorption spectrometry and ultra high-performance liquid tandem mass spectrometry(UPLC-MS)were applied to investigate the changes in dephosphorylation degree.Moreover,the digestibility of dephosphorylated MPC was also investigated using an in vitro digestion model.The results showed that a series of MPC with dephosphorylation rate of 0~85.8%was obtained after the modification of MPC by PAP dephosphorylation.With the increase in dephosphorylation degree,the looser clots were observed,and the gastrointestinal digestibility of MPC increased under in vitro conditions.