Background and purpose: Traditionally, probiotics are extensively incorporated into fermented dairy products. Dairy products could cause two major problems including allergy to milk protein and lactose intolerance, which ultimately lead to limited consumption of these foods. Today, fruit or vegetable drinks are ideal sources of probiotics for consumers. In this study, we investigated the possibility of probiotic tomato juice production through fermentation by Lactobacillus acidophilus La5 and presence of whole or soluble phase of bitter almond gum as prebiotic. In addition, the viability of probiotic cells in this non-dairy drink and their resistance to simulated gastric digestion were assessed.

Materials and methods: The viability of Lactobacillus acidophilus La5 in five tomato juice mixtures, including tomato juice containing 0.5 and 1% (w/v) soluble phase of bitter almond gum (SBAG), as well as 0.5 and 1% (w/v) whole bitter almond gum (WBAG), and tomato juice without gum (as control), was assessed during 48 h of fermentation (at 37^°C) and 14 days of refrigeration (at 4^°C). All the samples were stored at 4^°C for seven days and then exposed to simulated gastric juice (SGJ) for 90 min.

Results: Compared to other juices, the highest survival rate of Lactobacillus acidophilus La5 was observed in fermented tomato juice containing 1% SBAG. Moreover, SBAG exhibited more prebiotic effects compared to WBAG. Tomato juice formulation as a probiotic product caused no undesirable sensory effect on the final product.

Conclusion: According to this study, SBAG increased the viability of Lactobacillus acidophilus La5 and could be used as a suitable prebiotic to prepare fermented tomato juice.