A study on the implications of NaCl reduction in the fermentation profile of Conservolea natural black olives.

This study examined the impact of different mixtures of NaCl, KCl, and CaCl(2) on the fermentation profiles of Conservolea natural black olives. Five different combinations of chloride salts were investigated, namely (i) 8% NaCl (control treatment), (ii) 4% NaCl and 4% KCl, (iii) 4% NaCl and 4% CaCl(2), (iv) 4% KCl and 4% CaCl(2), and (v) 2.6% NaCl-2.6% KCl-2.6% CaCl(2). The changes in the microbial association (lactic acid bacteria, yeasts, Enterobacteriaceae), pH, titratable acidity, organic acids, volatile compounds, and mineral content in olive flesh were analyzed. Results demonstrated that all salt combinations led to vigorous lactic acid processes based on the obtained values of pH (3.9-4.2) and titratable acidity (0.70-0.86 g lactic acid per 100 ml brine). Organoleptic evaluation was a critical factor in the acceptability of the final product. Increasing concentrations of CaCl(2) or a combination of KCl and CaCl(2) rendered the product bitter with low acceptability by the taste panel. Only one combination of chloride salts (4% NaCl and 4% KCl) could finally produce olives with lower sodium content and good organoleptic attributes. The results of this study could be employed by the Greek table olive industry in an attempt to produce natural black olives with less sodium without affecting the traditional taste of fermented olives in order to meet consumers' demand for low sodium dietary intake.

Efficacy of natamycin to control fungal growth in natural black olive fermentation.

The effect of natamycin as a fungal control agent in natural black olive fermentation according to the traditional anaerobic system was studied. Black Conservolea olives were subjected to spontaneous fermentation in 8% (w/v) NaCl brine solution (control treatment) or brine supplemented with 0.01% (w/v) natamycin (active compound) for an overall period of 60 days. The changes in the microbial association (lactic acid bacteria, yeasts, Enterobacteriaceae), pH, titratable acidity, organic acids, and volatile compounds were monitored throughout fermentation. The initial microbiota consisted of lactic acid bacteria, yeasts, and Enterobacteriaceae. The addition of natamycin in the brine inhibited the growth of yeasts, without affecting the population dynamics of bacteria, resulting in a more vigorous fermentation with higher titratable acidity compared to spontaneous control process. Moreover, the presence of natamycin inhibited mould spoilage caused by the development of fungal mycelium on the surface of the brine during the traditional anaerobic fermentation system employed widely in Greece in natural black olive processing. Natamycin could be an important component of a processing system to control fungal growth in natural black olive fermentation and at the same time it has the potential to enhance the process by favouring the growth of the indigenous population of lactic acid bacteria against other competing microorganisms.