Fermentation of Tomato Juice by Cell Immobilized Lactobacillus acidophilus

INTRODUCTION Probiotics are beneficial microorganisms. When ingested on a regular basis, probiotics can improve overall health, balance the microflora of the intestinal tract, enhance immune system function, and assist in the absorption of vitamins and minerals [1]. The most commonly consumed probiotics are lactic acid bacteria (LAB) including Lactobacillus acidophilus, Lactobacillus plantarum and Streptococcus lactis. Probiotic foods are usually produced by fermentation. However, for a probiotic product to be beneficial, it must contain at least 10 cfu/g of viable bacteria [2]. Probiotic products are commonly available in the form of fermented milk and yogurt. However, many individuals cannot consume these products because of their high cholesterol and lactose content. Fruit and vegetable juices have been suggested as media for cultivating probiotics because of their beneficial nutrients [3,4]; however probiotic stability in non-dairy products is difficult to maintain during storage. Probiotic encapsulation might solve this problem [5]. Encapsulation is one of the methods of cell immobilization. Advantages of immobilized cell technology include prevention of interfacial inactivation, stimulation of production and excretion of secondary metabolites, continuous utilization, and protection against disadvantageous and unfavorable environments [6-8]. In addition, immobilized cell Received : 19 June 2006. Revised : 7 August 2006. Accepted : 16 August 2006. Address reprint requests to : Jen-Horng Tsen, Department of Nutrition, China Medical University, 91 Hsueh-Shih Road, Taichung 404, Taiwan. Fermentation of Tomato Juice by Cell Immobilized Lactobacillus acidophilus