The role of autochthonous microorganisms in the production of table olives

Table olives are one of the most important traditional fermented vegetables in Southern European (Italy, Greece and Spain) countries. In the Greek-style production system, the fruits are placed directly into the brine, thus allowing the natural fermentation to take place. The spontaneous fermentations, that can last 8-12 months, are driven by mixed populations of microorganisms, mainly the epiphytic microbial population of yeasts and lactic acid bacteria (LAB) (Romero et al., 2004). At present, the industrial table olive process is not predictable and depends on the empirical experience of the producers. In order to avoid the unpredictability of the olive spontaneous fermentation, to improve the productive process and to constantly produce high-quality final products, the use of strains of LAB as starter cultures for olive production has been proposed (Sabatini and Marsilioet al., 2008; Panagou et al., 2008; Blana et al., 2014). However, in the last years, the importance and the potential applications of yeasts as starters for table olive processing has been recognized (Arroyo-López et al., 2008, 2012; Bevilacqua et al., 2012). Objectives: In the present work, we have studied the main physical, chemical and aromatic parameters of natural fermentations of Cellina di Nardò, Leccino, Kalamata and Conservolea table olives in order to determine chemical descriptors correlated to microbiological activities and the dynamics of microorganisms in order to select LAB and yeast strains as candidate autochthonous starter cultures. Conclusions: The identified chemical descriptors can be suitable to follow the trend and to control the outcome of the fermentation and a new protocol aimed to the selection of LAB and yeast strains as candidates autochthonous starters has been developed and applied (Bleve et al. 2014 a, b). Selected microbial starters have been successfully used to ferment olives in pilot and industrial-scale and a new method for table olive production has been set up (Bleve et al. 2103). The use of selected autochthonous starter cultures produced fermented table olives with improved organoleptic, sensorial and nutritional characteristics.