Chemical characterization of tomato juice fermented with bifidobacteria.

The objective of this research was to characterize the chemical properties of tomato juice fermented with bifidobacterial species. Tomato juice was prepared from fresh tomatoes and heated at 100 degrees C prior to fermentation. Bifidobacterium breve, Bifidobacterium longum, and Bifidobacterium infantis were inoculated in tomato juice and kept at 35 to 37 degrees C for up to 6 h. Fructooligosaccharide (FOS) was added to tomato juice prior to fermentation. The analyses for brix, total titratable acidity (TTA), pH, color, and lycopene content were conducted to characterize tomato juices fermented with bifidobacterial species. Heat treatment of tomato juice did not cause any significant changes in brix, pH, and TTA. Only the redness of tomato juice was significantly increased, as the heating time increased to 30 min. The tomato juices fermented with B. breve and B. longum exhibited significant decreases in pH (3.51 and 3.80, respectively) and significant increases in TTA (13.50 and 12.50, respectively) (P < 0.05). B. infantis did not cause any significant change in the chemical properties of tomato juice. The addition of FOS further improved the fermentation of tomato juice by bifidobacterial species. The lycopene contents of tomato juice were significantly increased from 88 to 113 microg/g by heat treatment at 100 degrees C (P < 0.05), however did not exhibit any significant change after fermentation with bifidobacterial species.