Effect of soybean protein hydrolysates on promotion of Streptococcus thermophilus
Trypsin, pepsin and alkaline protease are used for hydrolyzing soybean peotein isolate to test their effects on promoting the growth of Streptococcus thermophilus (S.t). M17 medium is used as basic medium, three kinds protein hydrolysates are added as experimental group, control medium is M17 medium with soybean protein, all of them are used to culture S.t and compare their effects on promotion of S.t, protein hydrolysates are analyzed by protein chromatography. The result shows that hydrolysates by alkaline protease can obviously increase the number of viable cells of S.t as one magnitude and content of peptide is high, which can provide a new optimum nutrigeon source for high-density cultivation of S.t.