Impact of lactic acid bacteria starter inoculation on the Physico-chemical, microbiological, volatiles and sensory properties of natural black Gemlik ( Olea europaea L., cv.) table olives

Traditionally, the fermentation of Gemlik table olives takes place spontaneously by the endogenous microbiota in Turkey, but the uncontrolled process during fermentation can result in the formation of off -flavours and a low sensory quality of the final product. In this research, the effects of inoculating naturally black Gemlik olives with Lactiplantibacillus pentosus and Lactiplantibacillus plantarum starter cultures on lactic fermentation development, volatile compounds, and sensory properties were investigated. Changes in spontaneous and culture inoculated olives were monitored during fermentation. Compared to spontaneous fermentation, rapid acidification, and sugar depletion were achieved with the use of starter cultures. Extra lactic acid bacteria and total yeast growth were detected in the inoculated trials during fermentation compared to the control trial. Volatile compounds in olives were extracted by the Purge and Trap method. 46 volatile compounds from 10 chemical groups have been identified in olives. In all three trials, volatile acids were the group of volatile compounds found in the top amount in olives, higher alcohols, phenols, aldehydes/ketones, and terpenes followed the volatile acids. Phenyl ethyl alcohol, alpha-farnesen, (Z)-3-hexene-1-ol and 2-hexanol, which give pleasant flavors, were determined to be in more quantity in olives with inoculated starter cultures. This study reveals that the use of starter culture provides advantages in the production of Gemlik variety table olives, positively affects aroma development, and improves sensory properties.