STUDIES ON THE FERMENTATION OF TOMATO JUICE BY USING κ‐CARRAGEENAN IMMOBILIZED LACTOBACILLUS ACIDOPHILUS

Lactobacillus acidophilus was entrapped in κ‐carrageenan and used to perform tomato juice fermentation in order to raise the survival of the bacteria in the product. Gel beads with diameters approximately 3.0 mm for cell immobilization were obtained, fresh raw tomatoes were used to make the juice and both free and immobilized cells were applied to carry out the fermentation for 80 h. Cell leakage from the gel beads and proliferation in the juice during the fermentation of immobilized cells were observed. The final viable cell number was attained with 10 7  cfu/mL in the juice, over 10 10  cfu/mL‐gel in gel beads for the fermentation of immobilized cell, and ca. 10 9  cfu/mL for the free cell. Immobilized cells could withstand the unfavorable low pH environment in tomato juice and better growth was achieved compared with free cells. The viable cell counts of immobilized L. acidophilus in the fermented tomato juice could maintain the level of 10 6   cfu/mL‐gel after 10 weeks of cold storage at 4C, in comparison with 10 4  cfu/mL for free cells. The immobilized cell fermented tomato juice also showed better overall palatability than that of free cells in cold storage at 4C.PRACTICAL APPLICATIONS This study demonstrates the applicability of κ‐carrageenan immobilized Lactobacillus acidophilus in the fermentation of tomato juice. The unfavorable low pH condition in tomato juice could be overcome and certain benefits were provided by cell immobilization.