Abstract:

The cold-set gels of whey protein containing bifidobacteria (CGWPCB) were prepared in the presence of glucono-δ-lactone (GDL). Their protection effect on bifidobacteria was investigated by means of acid tolerance test, and the gel structure was observed using scanning electron microscope (SEM), texture analyzer and laser particle size analyzer. The results showed that the cold-set gel particles of 5% and 6% WPI solution induced by 0.30% GDL present the best protection effect, the numbers of bifidobacteria decrease by two order of magnitude, and the survival rates of bifidobacteria are 1.7% and 2.1%, respectively 120 minutes later in the acid condition of pH 1.5; both the survival rates of bifidobacteria are 43.9% after 56 days in fruit juice stored at 4 ℃. In conclusion, cold-set gels of WPI, which have protection effect on bifodobacteria, can be applied in liquid products.

Key words: whey protein, cold-set gel, glucono-δ-lactone, bifidobacteria, protection