Various amino acids and the yeast extract, in amounts of 0.1%(w/v), were separately tested for their influence on the analytical parameters of lactic acid fermentation of cabbage juice with Bifidobacterium animalis subsp. lactis BB-12. Compared with the control, cysteine supplementation led to a decrease of the time to reach pH 5.0 of 6 times and an increase of lactic acid productivity of 1.22 times. After 48 h the ascorbic acid content was by 360.73% higher, the fermented cabbage juices being assigned into a distinct group applying both factor analysis (FA) and cluster analysis (CA). Tryptophan contributed to better values for lactic and acetic acid yield, while lysine and yeast extract especially for acetic acid yield. Valine and leucine were not able to improve the fermentation progress, estimated through the analyzed variables. This work would provide some helpful information for the development of various lacto-fermented vegetable juices using probiotic bacteria.

Carrots and red beet were evaluated as a potential substrate for the production of lactic acid fermented juices by Lactobacillus acidophilus and Bifidobacterium sp. Both strains were found capable to grow on the vegetable juices, but some differences between the dynamics of the processes, dependent not only by the culture but by the sort of the raw material, had as consequence the production of the final products with different stability degrees. The pH value of the carrot juices was decreased from an initial value by 6.45 to below 4.3 after 48 hours of lactic acid fermentation with Bifidobacterium sp., respectively to 3.84 after 24hours when Lactobacillus acidophilus was inoculated. The last strain has produced a significant increase of the titrable acidity, the fermented carrot juices containing 0.7% acids (expressed as lactic acid). In the case of the fermentation of the red beet juices it is also recommended the strain of Lactobacillus acidophilus, because the pH value decrease with 2 units in 24 hours. The best acidification kinetic parameters were determined in the case of the carrot juices fermented by Lactobacillus acidophilus. In the same process the value of the R squared coefficient showed a strong correlation between the biomass amount and the production of lactic acid.

In the present work, experiments oriented to the preparation of lactic acid fermented juices from green peppers, with and without growth factors added, were realised. The study was performed with a view to investigate the Bifidobacterium sp. (BB-12) growth in the vegetable juice through analysis of the dynamics of important final products of fermentation. Particularly, the dynamics of some chemical parameters (reducing sugars, titratable acidity, volatile acidity, amino acids content, ascorbic acid content) and microbiological parameters (number of colony forming units) was compared. The stability of the juices was higher after 24 hours, because the lactic acid content increased from 2.43 to 9.45g/l, while the pH has faster decreased close to 5. The final values of this parameter were ranged from 4.81 to 4.45. Referring to the reducing sugars content, the yield of the lactic acid production can be qualified as good. The dynamics of the amino acids content during the lactic acid fermentation of juices underlined that this nitrogen source was utilized in the final stage of the process. A positive influence of the cysteine on the preservation of the ascorbic acid content of the lacto-fermented juice was exercised, this one being by 48.75 times higher than in the control sample. The obtained results can be an argument in the development of functional foods, but from this point of view, it is necessary to extend the researches to a great number of bifidogenic and/or growth factors.