Effect of Process Variables on Survival of Bacteria in Probiotics Enriched Pomegranate Juice

Aims: The consumption of foods and beverages containing probiotic microorganisms is a growing, global consumer trend. In this research, production of probiotic pomegranate juice containing Lactobacillus plantarum and Lactobacillus delbrueckii was studied.

Study Design: Plackett-Burman statistical design was used to evaluate the impact of eleven process variables on the viability of both probiotics. Impact of incorporation of grape juice, tomato juice and pomegranate peel extract as well as phenolic compounds and vitamins have been investigated.

Place and Duration of Study: Department of Food Science and Technology, Varamin Branch, Islamic Azad University, Varamin, Tehran, Iran, between Sep 2012 and July 2013.

Methodology: Pomegranate juices were inoculated with probiotic bacteria and their survival was evaluated every week by pure plate method. The effect of 11 variables (in two levels) on survival of bacteria by the statistical design of Plackett-Burman was evaluated. For this purpose, 12 treatments in triplicate by the Minitab (version = 11.0) software at significant levels α= .01 were analyzed.

Results: The highest survival rate of L. plantarum (4.74 ×106 CFU/mL) and L. delbrueckii (4 ×106 CFU/mL) was obtained by 10% v/v inoculation of a 48 h inoculum culture in MRS broth medium to enriched pomegranate juice (10% v/v Grape juice, 5% v/v tomato juice, 0.1% v/v pomegranate peel extract and 2.0 g.L glucose) which was inoculated in anaerobic condition for 72 h at 37ºC and kept for 2 weeks at environment temperature. Sensory evaluation shows the probiotic juice was accepted by consumers with no significant difference in comparison to control in terms of taste, odour and overall acceptability (P>.05).

Conclusion: The results of this study suggest that grape, tomato juices and pomegranate peel extract exert a protective effect on L. plantarum and L. delbrueckii viability under acidic condition of pomegranate juice and storage time, which was associated with the chemical composition of them. This study indicates that develop of probiotic pomegranate juices with acceptable viability and stability of the probiotic is possible.