Phenolic trend and hygienic quality of green table olives fermented with Lactobacillus plantarum starter culture

In this paper, four different olive cultivars from Southern Italy, Carolea, Cassanese, Nocellara del Belice, Nocellara Messinese table olives, produced according to traditional fermentation processes, were evaluated with the aim of assessing the effect of selected starter cultures on growth of bacterial population and on olive phenols during fermentation. Only Cassanese and Nocellara del Belice inoculated samples reached a safe pH value under 4.6 after 90 days while maintaining it until the end of storage. The most representative phenols in brine samples analysed by HPLC-MS/MS were hydroxytyrosol and verbascoside. Among the analysed phenols, only hydroxytyrosol, caffeic acid and ferulic acid always increased during fermentation, while the others increased up to 90-120 days and then decreased. The Principal Component Analysis (PCA) performed on pH and phenol values highlighted three clusters of olive cultivars. Throughout the brining period, lactic acid bacteria were always present while staphylococci and coliform bacteria disappeared after 30 and 90 days, respectively.