Effect of increased β-lactoglobulin and whey protein concentration on the storage stability of UHT processed milk

The effects of addition of a beta-lactoglobulin-enriched powder (beta-fraction) (0.015-0.375 g/100 g milk) or whey powder (0.26-2.5 g/100 g milk) on the storage stability of UHT processed milk was examined. Increasing the whey protein content of milk by addition of beta-fraction or whey powder to raw milk delayed the onset of age-gelation in UHT milk samples. Addition of low concentrations of beta-fraction usually delayed gelation time by 4-8 weeks, while addition of larger amounts of beta-fraction or whey powder resulted in a further extension of time before gelation was apparent. The gelation occurred in the upper creamy layer of the sample and there was no increase in product viscosity normally associated with age-gelation. There was no clear trend observed on the effect of seasonal differences in milk composition on the gelation time.