CO2 and Acidification of Low-Salt Brine Promote Some Yeasts and Penalize Bacteria in Naturally Brined Black Table Olive Fermentation

Naturally fermented black table olives are typically processed in brine with a high NaCl content. Since salt is responsible for several cardiovascular problems, methods are needed to reduce the salt (NaCl) content in the olive flesh. In this study, we investigated the natural fermentation of healthy and damaged black table olives marinated in acidified low-salt brine under slightly pressurized CO₂ (spCO₂) conditions. Tests performed with healthy black table olives of the Leccino cultivar showed the presence of yeasts and the absence of bacteria and molds in the brine during the entire fermentation period. Among the yeasts, <i>Saccharomyces cerevisiae</i> prevailed, especially at the end of the fermentation period. Black table olives damaged by the olive fruit fly <i>Bactrocera oleae</i> (Rossi) were contaminated by various microorganisms, including enterobacteria and lactic acid bacteria, recorded mainly in fruit fly larvae. During fermentation with acidified low-salt brines under spCO₂, enterobacteria did not survive at the beginning of incubation, whereas the lactic acid <i>Leuconostoc mesenteroides</i> identified at the beginning of fermentation disappeared after 2 months of incubation. Among the yeasts that survived during the incubation, <i>S. cerevisiae</i> clearly prevailed. All results confirmed the antimicrobial activity of acidified low-salt brine in the presence of spCO₂. This technology may offer a potentially safer method for production of low-salt olives.