Treatment of green table olive solutions with ozone. Effect on their polyphenol content and on Lactobacillus pentosus and Saccharomyces cerevisiae growth.

Disposition of green table olives alkaline solutions (GTOS) remains a major task for the industry with serious environmental implications. The presence of high concentrations of polyphenols in olives also presents a problem for direct brining and successful fermentation step. In this study we evaluated the effect of ozone treated GTOS on the growth of Saccharomyces cerevisiae and Lactobacillus pentosus. GTOS were treated with ozone for 24 and 72 h. The treatment caused a rapid destruction of polyphenols but did not affect sugar concentration. S. cerevisiae grew in the original and treated liquids, although its maximum specific growth rate (mu(m)) and its population size increased as the ozone treatment was longer. L. pentosus was completely inhibited in the original and 24 h ozone treated GTOS, but grew in 72 h treated solutions. Co-culture with S. cerevisiae improved L. pentosus performance. Diluting the original GTOS with distilled water in several ratios, and adding MRS medium (50 g/L) to ensure nutrient availability, showed that a complete inhibition on L. pentosus did never occur; however, its mu(m) progressively increased, and the lag phase period (lambda) decreased linearly, with increasing dilutions levels. The inhibition effect was lower in 24 h ozone treated GTOS and disappeared completely in those treated for 72 h. Furthermore, treatment of GTOS with ozone always improved microbial growth.