o improve the quality of stirred yogurt
fermented with goat milk and explore the effects of transglutaminase (TG) on
the protein cross-linking degree of goat milk, stirred yogurt were treated by
TG (concentrations of 1, 2, 3 u/g protein); the pH, viscosity, water holding
capacity, flavor and the viable count changes in lactic acid bacteria during
storage were studied and the crosslinking degree of goat milk were analyzed
with SDS-PAGE electrophoresis. The results showed that the pH in storage period
of yogurt was significantly higher than the control group; the viscosity and
water holding capacity of stirred yogurt during storage increased significantly
and the effect was more obvious with the increase of TG concentration. The contents
of acetaldehyde and diacetyl decreased gradually, and the concentration of TG
was greater, the effect was more obvious. TG treatment inhibited significantly
the number ofStreptococcus thermophilusof stirred yogurt during storage, and with the increase of TG concentration,
the content of Streptococcus thermophilus was lower, while TG treatment had no
obvious effect onLactobacillus
bulgaricus. SDS-PAGE revealed that
the occurrence of noticeable cross-linked on kappa-casein and
alpha-lactalbumin when the goat milk treated by TG, which was beneficial to the
stability of yogurt gels.