COMPARISON OF ANTIFUNGAL PROPERTIES OF LACTOBACILLUS RHAMNOSUS AND LACTOBACILLUS REUTERI WITH POTASSIUM SORBATE IN THE IRANIAN UF-FETA CHEESE

This study was aimed to compare antifungal properties of two lactobacilli strains with potassium sorbate in cheese. In this regard, the effect of 10-fold cell-free extract of Lactobacillus rhamnosus PTCC 1637 and Lactobacillus reuteri PTCC 1655 was studied on the growth of mold and yeast in the Iranian UF-Feta Cheese during a 60-day ripening period at 4 degrees C. Additionally, the antifungal effect of potassium sorbate (300 and 500 ppm) and mixture of potassium sorbate and cell-free extract of tested bacteria were evaluated. The results showed that yeast and mold growth was occurred in both control and treated chesses, however, after 30 days storage, mold and yeast count was significantly lower in the cell free supernatant-treated UF-Feta cheese in comparison to the control cheese. Addition of potassium sorbate, as expected, significantly reduced mold and yeast growth in UF-Feta cheese during ripening period than control. On the other hand the result showed that mixture of probiotic extract and potassium sorbate had more efficiency in mold and yeast growth reduction than when the sorbate potassium was used alone. The highest fungal growth inhibition was achieved by application of 2 mL cell-free extract of L. reuteri CCTP 1655 along with 500 ppm potassium sorbate. Generally, it could be concluded that cell-free supernatant of tested bacteria has potential for use as bio preservatives in cheese and although studied probiotic extracts are not as effective as sorbate potassium in preventing fungi and yeast growth, they can be useful in reduction of yeast and mold growth.