| Summary: | Undesired fermentation of fruit-derived beverages by fungal, yeast and bacterial spoilage organisms are among the major contributors of product losses in the food industry. As an alternative to chemical preservatives, the use of <i>Candida pyralidae</i> and <i>Pichia kluyveri</i> was assessed for antimicrobial activity against several yeasts (<i>Dekkera bruxellensis, Dekkera anomala, Zygosaccharomyces bailii</i>) and fungi (<i>Botrytis cinerea</i>, <i>Colletotrichum acutatum</i> and <i>Rhizopus stolonifer</i>) associated with spoilage of fruit and fruit-derived beverages. The antagonistic properties of <i>C. pyralidae</i> and <i>P. kluyveri</i> were evaluated on cheap solidified medium (grape pomace extract) as well as on fruits (grapes and apples). Volatile organic compounds (VOCs) from <i>C. pyralidae</i> and <i>P. kluyveri</i> deemed to have antimicrobial activity were identified by gas chromatography-mass spectrometry (GC-MS). A cell suspension of <i>C. pyralidae</i> and <i>P. kluyveri</i> showed growth inhibition activity against all spoilage microorganisms studied. Direct contact and extracellular VOCs were two of the mechanisms of inhibition. Twenty-five VOCs belonging to the categories of alcohols, organic acids and esters were identified as potential sources for the biocontrol activity observed in this study. This study reports, for the first time, the ability of <i>C. pyralidae</i> to inhibit fungal growth and also for <i>P. kluyveri</i> to show growth inhibition activity against spoilage organisms (<i>n</i> = 6) in a single study.
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