Biotechnological innovations aimed at debittering and quality improvement of table olives

Table olives represent a popular fermented product in the Mediterranean region (Perpetuini et al., 2020). The European production is basically concentrated in three countries: Spain, Greece and Italy (Speranza et al., 2022). However, table olives undergo alterations during the debittering process, frequently of microbial origin. To extend shelf life, industrial producers use preservatives (Casado et al., 2010). Recently, the increasing consumer demand for a quality product has led producers to seek alternative processing and preservation methods. Bioprotective microorganisms can counteract undesirable microbe development, safeguarding table olive safety (Vignolo et al.,2012). The bioprotective role in table olives is carried out through various mechanisms (Siedler et al.,2019). The most common is the ability to compete for nutrients and survive under extreme conditions (Shi et al.,2022). When selecting psychrophilic strains for table olive production, tolerance to salinity and varying pH levels is crucial. Additionally, the ability to synthesize bioactive compounds that hinder undesirable microorganisms is considered (Siedler et al.,2019). LAB are extensively studied for their inhibitory effects against Gram-positive and Gram-negative bacteria, as well as yeasts and filamentous fungi (Ağagündüz et al., 2022; Simões et al., 2022). Inoculating Lactiplantibacillus plantarum strains into table olives improves quality of table olives by reducing microbiological risks. In particular, a reduction in the incidence of gas pockets was observed in packaged olives (Ghabbour et al.,2016). While LAB dominate, certain yeast strains also exhibit bioprotective properties, albeit limited research and application (Campus et al., 2018). The utilization of these bioprotection technologies in the table olive supply chain remains limited at the industrial level. This project aims to thoroughly investigate these technologies by identifying LAB and/or yeast species suitable for pilot-scale testing and subsequent industrial level in the processing of the most widespread olive varieties in Sicily such as ‘Nocellara del Belice’, ‘Giarraffa’, and ‘Nocellara Etnea’, using common processing methods.