Preparation And Antioxidant And Promote Fementation Of Mung Bean Polypeptides

The degree of hydrolysis (DH) and nitrogen solution index (NSI) of mung bean protein hydrolysates obtained by alkaline protease, neutral protease and papain were studied and the results showed that alkaline protease hydrolysates presented higher DH% and NSI%. Mung bean protein had been hydrolysed with alkaline protease for 6 h. The DH% and NSI% reached 28.76% and 61.29%.Single-factor tests, which including temperature, pH, substrate concentration, enzyme substrate ratio (E/S) and hydrolysis time, were used to optimize the parameters of alkaline protease. On the basis of the results of single-factor tests, the DH% and NSI% was used a as the response value to build up a response surface methodology to optimize the process of mung bean protein hydrolysis by alkaline protease. The results showed:pH value is 8.95, temperature is 57℃, enzyme to substrate ratio(E/S) is 3.5%, mung bean protein concentration is 2% and the time is 2 h. Hydrolyzing mung bean protein under the foregoing conditions, the DH% and NSI% reached 23.07% and 60.22%.The molecular weight (MW) distribution of mung bean protein hydorlysate was determined by G-25 gel chromatography the molecular weight (MW) distribution of mung bean protein hydorlysate ranged from 600 to 1400 Da. The macroporous adsorption resin was applied to desalination of mung bean protein hydrolysate. Under conditions of the flow rate of water washing 0.5BV and the desorption rate of 75% ethanol, the desaltionrate reached about 91.5%, and the recovery of mung bean peptides was about 72.6%.The antioxidant activity of mung bean polypeptides were as follows:it has good reductive activity, the IC50 of hydroxyl radicals scavenging, hydrogen peroxide scavenging and liposome peroxide were 13.63 mg/mL,16.85 mg/mL and 10.31 mg/mL respectively. Mung bean polypeptides showed strong antioxidant capacity in the four antioxidant experiments.Mung bean polypeptides were added into fermented milk as fermentation Promoter for lactic acid fermentation. The promotive effect of mung bean polypeptides on the growth and acid production of lactobacillus was studied. The results showed:The mung bean polypeptides shorten yogurt fermentation time by 45 min.The flavor substance of yogurt was detective by solid phase microextraction (SPME) and GC-MS. The results showed:The mung bean polypeptides enhanced the content of 2,3-butanedione,2-butanone and acetic acid.