Production of table olives by using probiotic starter culture and identification of lactic acid bacteria in olives processed by spontaneous fermentation

Different techniques are applied all over the world to eliminate the bitterness of olive fruits. The fermentation method comes at the beginning of these techniques. Physical, chemical, and a large number of factors, such as microbiological properties of olive fruits, environmental factors (temperature, humidity, etc.) make olive fermentation a complex process. Due to this, fermentation conditions and microbial optimization of table olives have not yet been achieved. For this reason, around the world table olives are generally processed according to the spontaneous fermentation method. This study aimed to optimize Gemlik green and black olive fermentation and to increase the functional properties. For this purpose, the initial microbial population of olive fruits was tried to be reduced by the combined use of ultraviolet (UV) and ultrasound (US) applications, and Lactobacillus plantarum MF376, Lactobacillus plantarum 299v, and Lactobacillus rhamnosus HA-114 strains with probiotic properties were used as starter cultures. At the end of the study, pH values of Gemlik green and black olive brine were determined to be between 4.20-4.84 and 3.94-4.00, respectively. The titration acidity values were determined (Lactic acid) as 0.266-0.452% in Gemlik green olive brines and 0.815-1.013% in Gemlik black olive brines. MRSA count results of Gemlik green olive and black olive brine were determined as 2.09-3.16 log cfu/ml and 5.33-5.96 log cfu/ml, respectively. Total phenolic substance determination results of Gemlik green and black olive fruits were determined as 182.91-1022.69 mg GAE/100 g and 228.09-1870.3 mg GAE/100 g, respectively. Antioxidant capacities of Gemlik green and black olive fruits were determined as 81.23-435.56 μmol TE/100 g and 308.41-495.16 μmol TE/100 g by FRAP method, 87.78-224.25 μmol TE/100 g and 61.72-287.65 μmol TE/100 g by TEAC method, and 14.97-117.5 μmol TE/100 g and 10.19-23.99 μmol TE/100 g by DPPH treatment. Oleuropein contents of Gemlik green and black olive fruits were determined between 34.8-117.5 ppm and 36.3-87.6 ppm, respectively. It was determined that the yeasts were Wickerhamomyces anomalus and the lactic acid bacteria were Lactobacillus plantarum, which were isolated from the control group of Gemlik green olive fruits and identified by isolating from the control group of Gemlik black olive. According to the data obtained at the end of the study, it has been found that UV+ US application reduces the microbial load of raw fruit. In addition, it has been determined that the use of probiotic starter culture improves fermentation conditions, increases the acidity of brine quickly, and accelerates the breakdown of oleuropein in olive fruits.