Effect of whey protein hydrolysates with different molecular weight on fatigue induced by swimming exercise in mice

BACKGROUND In order to improve the antioxidant and anti‐fatigue capacities of whey protein for wider utilization, it was hydrolyzed by chymotrypsin ( EC 3.4.21.1) to produce whey protein hydrolysate ( WPH ). Fractions of WPH with different molecular weight ( MW ) were separated by ultrafiltration. Kunming mice in various treatment groups were orally administered (1.5 g kg −1 body weight) whey protein isolate ( WPI ), WPH or WPHs with different MW (<5, 5–10, 10–30 or >30 kDa ) for 6 weeks to explore whether different MW fractions of WPH affected mice fatigue.RESULTS Compared with the control group (orally administered 9 g kg −1 saline) or the WPI group, low‐ MW (<10 kDa ) WPH groups showed prolonged swimming time ( P < 0.05) and had higher concentrations ( P < 0.05) of glucose, non‐esterfied fatty acid, liver glycogen, superoxide dismutase and glutathione peroxidase and lower concentration of lactate. Low‐ MW (<10 kDa ) WPHs had higher hydroxyl‐ and α , α ‐diphenyl‐ β ‐picrylhydrazyl‐scavenging abilities and ferrous‐chelating capacity than WPI .CONCLUSION The results proved that low‐ MW (<10 kDa ) WPHs with higher anti‐fatigue capacity showed higher free radical‐scavenging and ferrous‐chelating activities. © 2013 Society of Chemical Industry