The effects of β-lactoglobulin genetic variants A and B on the functional properties of whey under different conditions

Partially delactosated and demineralized whey protein powders were purified from pooled milks of individual cows homozygous for the β-lactoglobulin (β-Lg) genetic variants A and B ( whey A and whey B). The protein composition of the two samples was similar. The two whey protein powders were dissolved in water at different pH (2, 4.5, 6.8) and NaCl concentrations (150 and 400 mmol/dm3), and emulsions were made utilizing grape-seed oil. Emulsion stability (ES), emulsion activity index (EAI) and emulsion capacity (EC) were examined. The results showed the influence of the two genetic variants of β-Lg on the functional behaviour of whey. Emulsion obtained from B powder solutions showed the higher stability at the different test conditions. The best results occurred at pH 6.8 with no significant differences between the two tested NaCl concentrations. At pH2 and 400 mmol/dm3 NaCl, both samples did not demonstrate any stability. Data on emulsion capacity indicated that whey B is less affected by the different physicochemical conditions tested (pH, NaCl concentration, heat treatment at 90°Cl5 min), while whey A gave the highest and the lowest EC values depending on the experimental conditions.