Abstract
Milk fat globule membrane (MFGM) fractions were isolated from fresh raw cream at different temperatures and pH values. The polar lipid (PL) composition of these fractions, and of commercially produced alpha-serum, beta-serum, and buttermilk powder samples, was determined. Lower temperature and pH during churning increased the total level of PLs in the MFGM fractions. Phosphatidylethanolamine (31-36% of total PLs), phosphatidylcholine (31-39%), and sphingomyelin (13-24%) were the major PLs in all MFGM fractions; phosphatidylserine (2-7%) and phosphatidylinositol (2-4%) were the minor ones. The b-serum fraction had the highest total PL content of the commercial samples (2.9 mg g(-1) fat); buttermilk powder contained the least amount of total PL amongst all fractions (0.99 mg g(-1)). Processing temperature and pH can therefore influence the PL composition, likely due to how the treatments impact on the different PLs that are located within different regions within the MFGM trilayer structure. (c) 2018 Elsevier Ltd. All rights reserved.