Co-inoculation approach combining lactic acid bacteria and yeasts to enhance the production of Nocellara del Belice green split table olives

Table olives are among the most popular fermented foods in the Mediterranean area. In Sicily, split green table olives are produced on a small scale and are traditionally used as an ingredient in various recipes. In order to improve and standardise the production of Nocellara del Belice split table olives, experimental productions inoculated with a commercial LAB strain and two previously selected yeast strains were carried out. The experimental plan included the production of three experimental batches (SO, split olives): SO1, control production inoculated with the commercial strain Lactiplantibacillus pentosus OM13; SO2, L. pentosus OM13 was coinoculated with Candida boidinii LC1; SO3, L. pentosus OM13 in co-inoculum with C. norvegica OC10. Throughout the 90-day fermentation period, pH, salinity, and microbiological populations were closely monitored. At the conclusion of fermentation, the olives were assessed for colour, pulp hardness, volatile organic compounds, and sensory characteristics. During the process, the inoculated lactobacilli and yeast strains became the dominant populations, reaching levels above 6 Log CFU/mL and dominance percentages exceeding 80%. In the in the coinoculated trials, brine acidification achieved pH values below 4.5 after 75 days, compared to the control trial, which reached this level after 21 days. The co-inoculation approach effectively limited the growth of undesirable microorganisms, resulting in firmer pulp. This combination of inocula also allowed for aromatic differentiation between the trials. Sensory analysis revealed differences in texture, flavour, and overall appreciation, with no unpleasant odours or tastes detected.