Proteomic Comparisons of Caprine Milk Whole Cream Buttermilk Whey and Cheese Whey Cream Buttermilk

Buttermilk, a potential material used to produce milk fat globule membrane (MFGM), is obtained as a byproduct of butter making from milk whole cream and cheese whey cream. This study investigated the effects of rennet and acid coagulation on the protein profiles of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW). They were compared to those of whey cream buttermilk (WCB). Rennet coagulation was more efficient in removing casein, while retaining more IgG and lactoferrin than acid coagulation. BRW had more MFGM than BAW. Butyrophilin, xanthine dehydrogenase, and mucin1 were significantly higher (P < 0.05) in BRW, while fatty acid-binding protein 3 was enriched in BAW. KEGG analysis showed that complement and coagulation cascades had the greatest differences, and the abundance of proteins involved in this signaling pathway in BRW and BAW was higher, suggesting their potential anticoagulant and anti-inflammatory activity. BAW had higher apolipoprotein A4 and transcobalamin 2, which are essential carriers for transporting long-chain fatty acids and vitamin B12 from the intestine to the blood. Therefore, BAW intake might improve lipids and vitamin B12 absorption. This study can help deepen the understanding of protein composition of MFGM-enriched whey and facilitate the production of MFGM proteins for infants and old-aged populations.酪乳（Buttermilk）是一种可用于制备乳脂肪球膜（milk fat globule membrane, MFGM）的潜在原料，其系以全脂乳奶油及干酪乳清奶油制备黄油过程中产生的副产物。本研究考察了凝乳酶法与酸法凝固工艺对酪乳凝乳酶凝固乳清（buttermilk rennet-coagulated whey, BRW）及酪乳酸凝固乳清（buttermilk acid-coagulated whey, BAW）蛋白质组谱的影响，并以乳清奶油酪乳（whey cream buttermilk, WCB）作为对照进行比较。相较于酸法凝固，凝乳酶法凝固在去除酪蛋白方面效率更高，同时保留了更多的免疫球蛋白G（IgG）与乳铁蛋白（lactoferrin）。BRW的MFGM含量高于BAW。嗜乳脂蛋白（Butyrophilin）、黄嘌呤脱氢酶（xanthine dehydrogenase）及黏蛋白1（mucin1）在BRW中显著上调（P < 0.05），而脂肪酸结合蛋白3（fatty acid-binding protein 3）在BAW中富集度更高。京都基因与基因组百科全书（KEGG）分析显示，补体与凝血级联反应通路差异最为显著，且BRW与BAW中该信号通路相关蛋白的丰度更高，提示二者具备潜在的抗凝血与抗炎活性。BAW中含有更高水平的载脂蛋白A4（apolipoprotein A4）与转钴胺素2（transcobalamin 2），二者是将长链脂肪酸与维生素B12从肠道转运至血液的必需载体。因此，摄入BAW或可改善脂质与维生素B12的吸收效率。本研究有助于加深对富MFGM乳清蛋白质组成的理解，并可为面向婴幼儿与老年人群的MFGM蛋白产品的生产提供助力。