Improving soft cheese quality using growth stimulator for Bifidobacterium bifidum

The effectiveness of supplementation the bifidobacterial growth medium with different concentrations of sterilized Propionibacterium thoenii P-127 metabolites was assessed. Supplementation the growth medium of Bifidobacterium bifidum with P. thoenii P-127 metabolites produced better antimicrobial activity than treatment involving either metabolites alone. Supplementation the B. bifidum growth medium with 1% (v/v) sterilized P. thoenii P-127 metabolites was found to be the most active against tested bacteria and yeasts and moulds. The efficacy of the combination between B. bifidum and P. thoenii P-127 or its metabolites as biopreservative as well as their influence on B. bifidum growth were evaluated in Domiati cheese overlong storage (8 weeks) at 7°C. Addition of P. thoenii P-127 or 1 % (v/v) of its metabolites stimulated the growth of B. bifidum and lactic starter and simultaneously produced antimicrobial metabolites against coliform, psychrotrophic bacteria and yeasts and moulds. Cheese made with lactic starter, P. thoenii P-127 and B. bifidum had the highest organoleptic scores when fresh and throughout storage followed by that made with lactic starter, B. bifidum and 1 % P. thoenii P-127 metabolites. Results suggest that the use of the combination of P. thoenii P-127 or its metabolites together with cheese starter and B. bifidum are useful to improve the keeping quality and contribute a taste to the soft cheese.