Evaluating the efficacy of brine acidification as implemented by the Greek table olive industry on the fermentation profile of Conservolea green olives

Abstract

The efficacy of different brine acidification treatments on the fermentation profile of Conservolea green olives processed by the Spanish method was evaluated. The treatments included: (a) acidification with CO2 gas, and (b) acidification with a mixture of lactic acid and HCl. Both processes were compared against a traditional fermentation with no acidification of the brine. Microbial growth, pH, acidity, organic acids, and volatile compounds were monitored for four months. Chemometric analysis was employed to differentiate the processes based on the profile of lactic acid bacteria (LAB) and yeasts, organic acids, and volatile compounds in the brines. Results showed that acidification of the brine with CO2 and lactic/HCl acids resulted in successful lactic fermentation processes. Lactic and acetic were the main organic acids measured in the brine by HPLC, whereas ethanol and methanol were the main volatile compounds quantified by headspace GC. A high concentration of methanol was found in the acidified brines exceeding even the concentration of ethanol in the end of the process. Sensory evaluation on the final product showed no difference among the three processes. Chemometric analysis was effective in discriminating the different fermentation profiles providing interesting perspectives in the applicability of this approach in olive fermentation.