INDUCED LACTIC-ACID FERMENTATION DURING THE PRESERVATION STAGE OF RIPE OLIVES FROM HOJIBLANCA CULTIVAR

The influence of initial sodium chloride concentration (6 and 0%, w/v) , acetic acid concentration (0.6, 0.3 and 0.0%, v/v), type of process (natural and inoculated), and storage system (anaerobic and aerobic) o n the inducement of a lactic fermentation for the preservation stage o f Hojiblanca cultivar ripe olives was investigated. The addition of 6% NaCl prevented colonization by lactic acid bacteria in all cases. A h igh level of acetic acid (0.6%) was effective in preserving olives for 2 months, although yeast growth was not inhibited for longer periods of storage. Natural growth of Lactobacillus plantarum did not occur. I noculation with this micro-organism was effective only in the two trea tments with tap water (with no NaCl) as the initial covering solution, although survival was reduced to a half of the added organisms when t he initial pH was corrected with 0.3% acetic acid. In these two treatm ents pH quickly reached appropriate values ( < 4.0) for olive stabiliz ation. Aerobic conditions led to low concentrations of carbon dioxide, without disturbing growth of lactic acid bacteria. Thus, the aerobic lactic acid fermentation, with tap water initially, was the most adequ ate preservation procedure for the storage of ripe olives prior to the ir oxidation treatment. Results of trials conducted on an industrial s cale showed the same pattern and confirmed the viability of the new pr ocedure.