ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF BOVINE WHEY PROTEINS HYDROLYSED WITH SELECTED LACTOBACILLUS STRAINS

Abstract

The present study investigated the antioxidant and antibacterial properties of hydrolysates obtained from bovine whey proteins, after hydrolysis with Lactobacillus plantarum strains isolated from ewe milk and Lactobacillus brevis isolated from camel milk. The aim here was to valorize whey proteins and to constitute local collection of bacteria, with potentially interesting technological and biological features. The protein hydrolysis was determined by degree of hydrolysis (DH) and electrophoresis SDS–PAGE, and then optimized using temperature, pH, cells/whey proteins ratio and time incubation. Antioxidant activity of hydrolysates was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) free radicals scavenging methods. The antibacterial activity was examined by the agar well diffusion assay. The results revealed that Lb. plantarum LBBS2 and Lb. plantarum LBM2 exhibited an optimum of hydrolysis of whey proteins at pH 7, at 30 °C, with (2/1) as ratio cells/whey proteins and after 48 h of incubation. Under these conditions, the hydrolysates exhibited an antibacterial activity against Gram positive and Gram negative bacteria, including some pathogenic and spoilage microorganisms.  Meanwhile, scavenging radical properties by the same hydrolysates reached a maximum after 24 h. These results suggest that Lb. plantarum LBBS2 and Lb. plantarum LBM2 could be used as new potential adjunct bacteria with interesting proteolytic activity. Moreover, milk whey which is the main by-product of food industry could be used for the production of molecules with a promising interest as antioxidants and antibacterials.