Antioxidant Property Of Whey Hydrolysates

The utilization of whey and the study of the functional properties of whey have become increasingly popular in recent years. Whey was proved to be antioxidative in prior investigations. This study was focused on the methods of improving the antioxidative activity of whey. Whey was hydrolyzed by protease and fermented by lactic acid bacteria to boost antioxidative activity. The hydrolysate and fermented product were tested in vivo using mice. A new pathway of utilizing whey was provided in this study.The acid whey was prepared before the hydrolysis. The orthogonal test was conducted after the single factor tests. The optimized hydrolysis parameters included:temperature55℃, pH8.5, E/S2%, and hydrolysis time3h. The ability to eliminate free radical of the hydrolysate was up to68.54%. In this condition, the ability to eliminate free radicals of the fermented product was up to55.45%, and that ability of the original whey was32.27%. It proved that the antioxidative activity of the whey could be improved after hydrolyzed by protease.Ten lactic acid bacteria were isolated from yoghurt. Lactobacillus helveticus was proved to be with the highest protease activity compared with the10lactic acid bacteria and lactobacillus plantarum. The whey was fermented by lactobacillus helveticus. The optimal fermentation conditions were as following:incubation temperature37℃, initial pH6.0, inoculation5%(vol/vol), and fermented for18h. In this condition, the ability to eliminate free radicals of the fermented product was up to54.73%, and that ability of the original whey was33.21%. So it was proved that being fermented by lactobacillus helveticus could improve the antioxidant property of whey significantly. It was proved that after fermented by the lactobacillus helveticus. the antioxidative activity of the whey could be improved, and developed a new way to prepare the antioxidative peptides from whey. There were a small number of free sulfhydryls in the fermented products, and the quantity of sulfhydryls was not relevant with the antioxidative activity of products. It proved that sulfhydryl did not play an important role in the antioxidative activity of fermented whey.Animal test in mice indicated that the antioxidative activity of whey products of hydrolyzed by protease and fermented by lactobacillus helveticus were better than the untreated whey. The products hydrolyzed by protease and the products fermented by lactobacillus helveticus improved the activities of SOD and GSH-Px in the liver and serum of mice significantly, but could not decrease the quantity of MDA in the liver and serum of mice obviously. Therefore, the animal test proved that the whey protease-hydrolyzed by and lactobacillus helveticus-fermented both improved the antioxidative activity of whey and their antioxidative activities were better than the untreated whey.