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

The effects of addition of a beta-lactoglobulin-enriched powder (beta-fract ion) (0.015-0.375 g/100 g milk) or whey powder (0.26-2.5 g/100 g milk) on t he storage stability of UHT processed milk was examined. Increasing the whe y protein content of milk by addition of beta-fraction or whey powder to ra w milk delayed the onset of age-gelation in UHT milk samples. Addition of l ow concentrations of beta-fraction usually delayed gelation time by 4-8 wee ks, while addition of larger amounts of beta-fraction or whey powder result ed in a further extension of time before gelation was apparent. The gelatio n occurred in the upper creamy layer of the sample and there was no increas e in product viscosity normally associated with age-gelation. There was no clear trend observed on the effect of seasonal differences in milk composit ion on the gelation time.