Study regarding some metabolic features during lactic acid fermentation of vegetable juices

摘要

In the current work, experiments oriented to the preparation of lactic acid fermented vegetable juices were carried out. The study was performed to investigate the metabolic pathways of lactic acid bacteria originated from the epiphytic microbiota of vegetables through analysis of the dynamics of some important products of fermentation. Particularly the evolution of some chemical (reducing sugars, lactic acid, amino acids, nitrites) and microbiological (number of viable lactic acid bacteria) parameters was compared. The stability of the juices was higher after 96 hours of fermentation because the lactic acid content increased from 0.06 to 1.41g/100ml. The amount of consumed reducing sugars of the juices, respectively the population of useful bacteria were correlated with the lactic acid production. An important indicator for the metabolism of lactic acid bacteria involved in the fermentative processes was considered also the amount of carbon dioxide, which was reached a maximum value of 0.39g/100ml. The dynamics of the amino acids content during the lactic acid fermentation of juices underlined that the pre-digestion of proteins improves the nutritional quality of the final products, while the decrease of the nitrites content was considered significant to point out the denitrification activity of lactic acid bacteria.