Introduction and comparison of measurement methods of antifungal properties of lactic acid bacteria in cheese

Various laboratory methods have been developed to evaluate the effectiveness of anti mould effect of lactic acid bacteria. However، most of these investigations have been conducted in culture medium. Due to the occurrence of complex interaction between food components and antimicrobial substances produced by lactic acid bacteria، the result achieved from these studies may be different from those seen in food model. In various studies growth inhibition of molds on the surface of foods are considered as antifungal activity. Consequently، introduction and comparison of efficient methods for evaluation of anti mould effect of lactic acid bacteria would be helpful. In this study، antifungal activity of lactic acid bacteria inoculated in cheese was estimated using Microdilution method. Pieces of cheese samples were overlaid with molds and the antifungal effect of this bacteria was studied against Aspergillus flavus and Aspergillus parasiticus. All three methods showed the effectiveness of lactic bacteria on mold inhibition. Comparison of the results showed that there was significant positive correlation between antifungal overlay assay and direct growth of mold on cheese، since this two test showed antifungal effect in the same way including interaction between bacteria and mold and also producing antifungal compound.