Virgin Olive Oil Quality Is Affected by the Microbiota that Comprise the Biotic Fraction of the Oil

Abstract

This review summarizes the current knowledge on the effects of oil-borne yeasts on the physicochemical, sensorial, and health-related characteristics of virgin olive oil (VOO) during storage. Bacteria, yeasts, and molds constitute the biotic fraction of freshly produced VOO. During storage, the bacteria and molds often die after a short period, while the yeasts survive and condition the quality of VOO. To date, approximately twenty-four yeast species have been isolated from different types of olive oil and its by-products, and seven of these species have been identified as new species. The activity of some yeasts of the biotic fraction of olive oil improves the sensorial characteristics of VOO. Some yeasts can also worsen the quality of the product by allowing the appearance of defects, oxidation of polar phenols, and triacylglycerol hydrolysis. Some yeast species of VOO show in vitro beneficial health effects, such as probiotic and antioxidant activities.

Keywords: biotic fraction; technological and health properties; virgin olive oil (VOO); virgin olive oil quality; yeast species.

Figure 1

SEM observation of the Yamadazyma terventina 2092 yeast strain after three months of incubation in virgin olive oil (VOO) with low (A) and high (B) total polar phenolic content; (C) Yeast growth in the CMA medium.