Lipid composition of whey protein concentrates manufactured commercially and in the laboratory

Freeze-dried whey protein concentrates, containing 35 and 75% protein and varying amounts of residual lipids, were manufactured by pretreating whey with calcium chloride and heat. These and commercial whey protein concentrates were subjected to proximate analysis, and lipid classes, phospholipid classes, FFA, and monoacylglycerol composition were determined. The pretreatment of whey with calcium chloride and heat, followed by centrifugal clarification, resulted in whey protein concentrate that had significantly lower total lipids and a lower lipid to protein ratio. Higher removal of lipids through higher calcium addition resulted in higher protein losses. The commercial whey protein concentrate had ratios of lipid to protein that were significantly higher than all experimental whey protein concentrates. Triacylglycerols were the major lipid class, followed by phospholipids, diacylglycerols, FFA, cholesterol esters, cholesterol, and monoacylglycerol. The pretreatment significantly increased the proportions of phospholipid and monoacylglycerol and decreased the proportion of triacylglycerol. Three major phospholipids in whey protein concentrates were sphingomyelin, phosphatidyl choline, and phosphatidyl ethanolamine, followed by phosphatidyl inositol, phosphatidyl serine, and cerebrosides. The pretreatment significantly reduced the proportion of phosphotidyl ethanolamine but had no effect on the FFA composition of whey protein concentrates. The FFA from whey protein concentrates included significantly higher butyric acid and lower oleic, caproic, and caprylic acids than in milk. The pretreatment had no effect on monoacylglycerol composition. The most monoacylglycerols present were C-16:0 (sn-1), followed by C-8:0 (sn-1), C-18:0 (sn-1), C-18:1 (sn-1), C-14:0 (sn-1), C-18:0(Sn-2), C-16:0 (sn-2), C-12:0 (sn-1), and C-10:0 (sn-1).