Characteristics of the fermentation process that occurs during the storage in brine of Hojiblanca cultivar, used to elaborate ripe olives

Abstract

The paper studies the changes of the physico-chemical and microbiological characteristics of the fermentation in aerobic conditions that occur during the storage stage of Hojiblanca cultivar used to elaborate ripe olives. Assayed treatments include all the conditions used at industrial level (correction of initial pH to 4,0-4,2 units with acetic acid, sodium chloride concentration ranging between 3 and 6%, green to yellow-pink green fruits and bubling of air at a rate of 0,3 liter per hour and liter of the vessel capacity). The process was characterized by a maintenance of the pH values, a slow sugar consumption, very low content of carbon dioxide and progressive increase of the salt concentration. Gram-negative rods and Bacillus grew at the beginning of the process; however, the most representative germs of these fermentation were the yeasts, whose population grew rapidly from brining (at higher rate as the salt content was slower). They remained throughout the storage, although after 180 days a decrease tendency was observed. The most representative species were: Pichía membranae faciens (51% of frequency), Pichía fementans (6%) and Hansenula polymorpha (6%). No gas-pocket or shrivelling was appreciated in any treatment.