A Two-Step Strategy for Controlling Spoilage Yeasts in Table Olive Preservation: Acid Treatment and Bioprotective Culture

Abstract

Yeast strains, including Saccharomyces cerevisiae or Wickerhamomyces anomalus, play an important dual role during olive fermentation, acting as either desirable or spoilage microorganisms depending on the stage. Consequently, the table olive industry must ensure product stability through thermal treatments or by adding chemical preservatives. In this context, two spoilage yeast strains were isolated and identified as a deterioration agent from a spoiled batch of packaged olives. The present study proposes a clean-label alternative to conventional preservation techniques using different weak organic acids to control the growth of spoilage yeast strains in table olives, which could be used alongside Lactiplantibacillus plantarum as a bioprotective culture. The efficacy of acetic, citric, and lactic acids as organic acids in counteracting spoilage yeast proliferation was demonstrated at pH values below 4.2; however, they also affect the survival of the bacteria. The findings of the in vivo challenge test demonstrated that the protective culture remained viable throughout the storage and the absence of spoilage symptoms in the packaged olives. These results support a two-step biopreservation treatment strategy that exhibited a remarkable capacity to impede the growth of spoilage yeasts and highlight the potential industrial applicability of this approach.