Wild yeasts involved in the natural fermentation of ‘Almagro’ eggplants fruits

Abstract

The Almagro eggplant is a vegetable used in a traditional pickle made in Spain through a natural process of fermentation for several days in a brine solution.The aim of the present work was to study the population of yeast present in fruits and brines during the industrial processing of Almagro eggplants in two different factories. Total yeast counts obtained in factory A were about 7–8 log CFU/mL, with slightly lower values determined for the fruits. In contrast, in factory B the counts were lower than 2 log CFU/mL with the highest values found in the post-fermentative stage.From a total of 380 isolates only eight different species were identified. In factory A the major species was Pichia occidentalis (82%). In addition, Kazachstania exigua, K. unispora and Zygosaccharomyces bailii were also isolated. In factory B the main species isolated was Candida ethanolica (40%) followed by Pichia kudriavzevii, Issatchenkia orientalis, P. occidentalis and P. manshurica. Only intraspecific differences for P. mashurica were found by RAPD-M13. The results provided a valuable information on yeast population biodiversity and dynamics in the naturally fermented Almagro's eggplants pickles.