Valorization of Buttermilk Powder to Produce an Ingredient Enriched in Milk Fat Globule Membrane (MFGM) for Applications in the Beverage Industry

Anna Carroll
Undergraduate (Food Science)
Dr. Rafael Jimenez-Flores
Food Science and Technology

Milk fat globule membrane (MFGM) is the multicomponent structure surrounding milk lipid globules. MFGM can be recovered from butter industry byproducts, including buttermilk. Supplementing a diet with MFGM has many potential health benefits throughout life impacting cognitive function, gut health, and the immune system. The research objective was to use buttermilk powder (BMP) to prepare an ingredient enriched in MFGM, reduced in casein and whey proteins, and suitable for beverage industry applications. A method for isolating and concentrating MFGM from rehydrated buttermilk (10% w/v BMP) was developed. Ammonium hydroxide, rennin, and acid treatments with or without trisodium citrate were tested. Ammonium hydroxide and trisodium citrate were expected to dissociate casein micelles; rennin and acid treatments were expected to precipitate out caseins. The effectiveness of these methods was evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and thin layer chromatography (TLC). Rennin precipitation (30°C, 1% CaCl2, pH 5.47, 5% rennin), followed by cheesecloth straining, addition of trisodium citrate (2.5%) to the liquid fraction, ultrafiltration (50 kDa; 4x concentration, 5x diafiltration), and centrifugation of the retentate was determined to be the best method to obtain a MFGM enriched semi-solid pellet (the ingredient). SDS-PAGE results showed this treatment had the most consistent enrichment in MFGM proteins, with a large reduction in casein proteins. Bands with calculated molecular weights of 169, 80, 58, 38, 21, and 20 kDa were detected, corresponding to MFGM proteins xanthine oxidase/dehydrase, butyrophilin, and lactadherin/periodic acid Schiff base 6 and 7 doublet, and to the milk proteins casein, beta lactoglobulin, and alpha lactalbumin. Difficulties separating out whey proteins could be attributed to protein-protein aggregates induced by heat treatment of BMP. TLC results confirmed the presence of MFGM phospholipids (sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine). Using the ingredient, several prototype probiotic MFGM enriched fruit-flavored beverages were made. Valorization of BMP can reduce dairy industrial waste and expand MFGM nutritional benefits to the general population beyond infant formula.