Effect of kaolin and copper based products and of starter cultures on green table olive fermentation

In the present study table olives treated in field with kaolin and copper based products against “olive-fruit fly” were fermented using two selected strains of lactic acid bacteria (LAB). The fermentation process was monitored up to 260 days from brining through physico-chemical, microbiological and sensorial analyses. Results showed a dominance of LAB and yeasts and low level of Enterobacteriaceae counts throughout the whole process both in un-treated and treated samples. When investigating the effect of the single treatments on microbial dynamics, ANOVA results highlighted that copper based products affected significantly the control sample, while the sample inoculated with LAB starters maintained high level throughout the process, guaranteeing the fermentation process. Different behavior was revealed by yeasts population, which was partially influenced by copper treatment at the beginning of the fermentation.The polyphasic approach used in the present study, which combined sensory evaluation to microbial counts and physico-chemical characteristics, let to the conclusion on the importance of starter cultures in fermentation of table olives especially those treated with “non-conventional” pesticide, which could be used to prevent olive fly damage.

► Table olives were treated in field with kaolin and copper based product.
► The effect of the single treatment during fermentation process was evaluated.
► Copper more than kaolin affected LAB concentration.
► Copper treated samples inoculated with both starters showed the highest level of LAB.
► Yeast count was not affected by any treatment during fermentation.