Comparative analysis of two antifungal Lactobacillus plantarum isolates and their application as bioprotectants in refrigerated foods.

AIMS: To compare the technological robustness of two antifungal Lactobacillus plantarum isolates and to assess their ability to inhibit growth of the spoilage yeast Rhodotorula mucilaginosa in two different refrigerated foods. METHODS AND
RESULTS: The effects of freeze-drying, thermal treatments and varying salt concentrations on the viability of two antifungal lactic acid bacteria (LAB) were examined. Antifungal compound(s) contained in the supernatant of both isolates were compared to commercially available food preservatives. Both isolates were used as dairy starter adjuncts in yoghurt and inoculants in orange juice to determine the antiyeast activity towards R. mucilaginosa. Yeast growth was retarded by the tested isolates in both food settings with one of the isolates, Lact. plantarum 16, being the most potent inhibitor.
CONCLUSIONS: Both lactobacilli exhibited considerable robustness to withstand processing treatments commonly encountered in a food industrial setting. The isolates were shown to possess potent antifungal activity in both in vivo and in vitro food models. SIGNIFICANCE AND IMPACT OF THE STUDY: The studied antifungal lactobacilli may represent safer and consumer-friendly alternatives to the use of chemical preservatives. This is the first report of antifungal Lact. plantarum exerting protective potential in yoghurt and orange juice.