Selection of yeasts for their anti-mold activity and prospective use in table olive fermentation

The growth of molds represents a major problem during table olive fermentation. Molds are recognized as spoilage agents and may reduce the product safety for their ability to produce mycotoxins. Yeasts, instead, are usually found in table olive processing and are generally considered desirable microorganisms for their technological properties. In the present study, a model system to select anti-mold yeasts usable as protective adjunct cultures in table olive fermentation was developed. Two hundred and ninety-nine strains of yeasts, isolated from cheese, olive, vinegar, and wine, were tested in vitro for their growth characteristics, fermentative activity, salt tolerance, and antagonistic activity against 10 mold strains isolated from table olives and olive brines. Experimental steps led to the selection of a strain of Yarrowia lipolytica exhibiting all the previously listed characteristics. Practical applications: A strain of Yarrowia lipolytica was selected because of its high potentiality as adjunct culture in table olive fermentation to contrast mold growth and increase the product quality and safety. The experimental model system developed in this study may be easily applied to select yeasts usable as adjunct cultures in table olive fermentation in order to contrast mold growth and increase the product safety. These outcomes showed how the use of selected yeasts constitutes a promising way to control mold growth during table olive fermentation.