Use of selected yeast starter cultures in industrial-scale processing of brined Taggiasca black table olives

The aim of this study was to evaluate the effects of six selected yeast starters on natural Taggiasca black table fermentations, in different brine solutions. The olives were subjected to fermentation in 8% (w/v) NaCl, 12% (w/v) NaCl and 12% (w/v) NaCl brine solutions with 0.3% (w/v) citric acid and inoculated with selected yeast starter strains belonging to the following species: Candida adriatica 1985, Candida diddensiae 2011, Cyteromyces matritensis 2005, Nakazawaea molendini-olei 2004, Saccharomyces cerevisiae 2046 and Wickerhamomyces anomalus 1960. Samples of brines and olives were analysed in the initial phase, then again after 30 and 120 days of fermentation. The yeast starters survived differently during the first 30 days of brine fermentation, depending on the NaCl concentration. After 120 days of fermentation N. molendini-olei 2004 and C. matritensis 2005 failed in the brines with 12% NaCl, while the yeast starter cultures C. diddensiae 2011, C. adriatica 1985 and W. anomalus 1960 showed the best performances in terms of survival and competitiveness towards wild yeasts of the brines. The physicochemical and sensorial analysis suggest a potential positive role of these yeasts during the debittering process of the Taggiasca table olives. Considering the combination between yeast starters and the fermentation conditions, the best indication occurred with the brines containing 12% NaCl acidified with citric acid.