Selection of starter cultures from olive skin to improve the quality of fermented table olives

The fermentation of olives, driven by indigenous microorganisms, can yield products of varying quality. This study evaluated the effectiveness of native starter cultures from the olive carposphere by fermenting Nocellara Messinese ripe olives in a 7% (w/v) salt brine by using two Lactic Acid Bacteria (LAB) and one yeast strain in single and mixed combinations. The LAB isolated from the carposphere were subjected to phenotypic and molecular analyses for identification, and then deposited at Unimore Microbial Culture Collection UMCC). The fermentation was monitored through microbiological analyses of the brine samples along with physicochemical analyses of the olive pulp at the beginning and end of fermentation, and sensory analysis of final products was performed. All the inocula reduced the pH, with the indigenous selected LAB, achieving safe level (pH<4.5) the fastest, while the uninoculated batch showed an increase in pH after 35 days of fermentation. Inoculated samples showed better total coliforms load reduction due to pronounced acidification and higher phenolic content in the brine. The findings suggest that using indigenous selected microbial starters leads to safe and effective productions, enhancing the quality of fermented table olives. Schematic diagram describing the selection of starter cultures from olive skin to improve the quality of fermented table olives, and the analyses performed. • The starter cultures reduced the pathogenic load of fermented olives. • Native starter cultures are useful to optimise biotechnological applications. • The used mix of starters reached and maintained the lowest pH value. • The native starter was identified and deposited as UMCC 3073.