A novel Lactobacillus pentosus-paired starter culture for Spanish-style green olive fermentation

A new starter culture consisting of two Lactobacillus pentosus strains was developed and successfully used for Spanish-style green olive fermentations in an industrial study. The inoculum, consisting of L. pentosus LP RJL2 and LP RJL3 strains, was inoculated in 10,000 kg glass fiber containers at 10⁶ CFU/ml and 10⁵ CFU/ml, final concentration respectively, in five different olive processing plants in the south of Spain. As a control, uninoculated fermentors were also used. In all inoculated fermentors, the paired starter rapidly colonized the brines to dominate the natural microbiota and persisted throughout fermentation. A decline in pH to reach about 5.0 was achieved in the first 15-20 days, reaching about 4.0 at the end of the process. The lactic acid concentration in brines increased rapidly in the first 20 days of fermentation (0.3-0.4 g/100 ml) to give values higher than 0.8 g/100 ml at the end of the process. In contrast, increasing lactic acid concentration was slower in uninoculated than in the inoculated brines, and the final concentrations were lower. Although reaching similar values at the end of the process, the decline in pH in uninoculated fermentors was slower than in the inoculated ones. These results show the efficacy of the new starter culture to control the lactic acid fermentation of Spanish-style green olives.