Effect of Various Gums on Skimmilk and Purified Milk Proteins

Abstract

Reactions of gums with skimmilk and with purified proteins were investigated using polyacrylamide gel (PAG) electrophoresis and centrifugation. Some gums caused no reaction with milk proteins, some caused wheying-off or coprecipitation that could be disrupted merely by dilution, and some caused a strong protein-gum interaction. Of the gums tested, only carrageenan, furcellaran, and algin altered any protein electrophoretic pattern. Carrageenan and furcellaran complexed -casein, preventing it from entering PAG. All 3 gums altered the migration pattern of bovine serum albumin (BSA) on PAG-urea-2-mercaptoethanol (PAG-urea-ME). Carrageenan and furcellaran caused sedimentation during centrifugation of [alpha]s- and [beta]-casein in the presence of Ca++ and [kappa]-casein with or without Ca++. Centrifugation of algin-protein mixtures did not alter them. Except for BSA, no whey proteins were measurably affected by these gums. Locust bean, guar, tragacanth, karaya, and carboxymethylcellulose gums caused wheying-off or coprecipitation, but electrophoretic migration of proteins was unaffected. Arabic, acacia, and larch gums had no measurable effect on any milk proteins. The effects of percentage of carrageenan and of the pH of the reaction mixtures were investigated and Rf''s of individual proteins on PAG, PAG-urea-ME, PAG-urea, and PAG-ME were measured.