Proteolytic Activity in Lactic Acid Bacteria from Iraq, Armenia and Bulgaria

ABSTRACT

Functional foods hold a great promise for future trends in human nutrition. Consumption of milk and milk products has a pronounced probiotic effects together with the expected modification of allergenic properties of milk due to the process of fermentation. The proteolytic system of lactic acid bacteria consists a cell wall bound proteinase and several intracellular peptidases, and can contribute to the liberation of bioactive peptides. Food-derived bioactive peptides are claimed to be health-enhancing components, which can be used for functional food.

In this study the attention was focused on homemade milk products from the Balkan region and also from Armenia and Iraq, as a source of newly potential starters for application in the food industry. In this context the aim of this study was to screen the proteolytic activity of newly isolated strains, by determination of the optimal conditions of proteolysis for reducing the milk proteins allergenicity. The proteolytic activity of 50 lactic acid strains was tested against major milk proteins. Some of the studied strains showed relatively high proteolytic activity towards α-casein, α-lactalbumin and β-lactoglobulin reducing their concentration proved by the HPLC analysis and Tricine-PAGE. Hydrolysis of milk protein generated peptides with antimicrobial effect against Esherichia coli, Staphylococcus aureus, Listeria innocua, Enterobacter aerogenes, Enterococcus avium and Salmonela choleraesuis.

Consequently to obtain a maximal effect of the product, a combination of strains with different properties could be used as starters in milk industry.

Keywords:

• casein
• proteases
• whey proteins
• allergy