J. Gen. Appl. Microbiol., 53, 215–219 (2007)

cently, the idea and the emphasis of probiotics has become more and more important. Probiotics can be applied to humans or other animals solely or by the mixture of living strains to ameliorate the balance of the indigenous microbial phase in the host (Marteau and Boutron-Ruault, 2002; Sanders, 1998). The most popular probiotics used commercially are lactic acid bacteria (Shortt, 1999). Lactic acid bacteria are widely distributed in nature. Those living in the human intestinal tract could maintain the stability and wellness of the microflora in the intestines, inhibit the multiplication of harmful microorganisms, and closely affect host health (Lee and Salminen, 1995). The nutrition and healthcare functions of lactic acid bacteria are being discovered and recognized gradually, and the fermentation products are receiving widespread consumer acceptance (Shortt, 1999). Lactobacillus rhamnosus is one of the lactic acid bacteria frequently used in probiotic foods. It can resist disadvantageous environment factors in the digestive tract, successfully colonize the intestinal tract, simultaneously adsorb to the epithelial cells in the tracts to form a defense, and prevent the infection of pathogens (Gopal et al., 2001). Besides, L. rhamnosus also can produce bacteriocin (Avonts et al., 2004), and possesses other probiotic effects (De Keersmaecker et al., 2006). Since obstacles to the function of intestinal tracts might be caused by the intake of antibiotics, or abnormal and incorrect dietary habits, scholars (Champagne and Gardner, 2005; Gueimonde et al., 2004) have suggested the dietary supplement of lactic acid bacteria to maintain and improve the health of human digestive tracts. This has facilitated the development of related functional foods and nutraceuticals (Hollingsworth, 2001; Senorans et al., 2003). Current food products with the addition of probiotics include sour cream, buttermilk, yoghurt, spreads, powdered milk, fruit juice, etc. (Wyers, 2004). However, owing to the lack of freezing resistance, the application of L. rhamnosus in frozen desserts is still limited. Low temperatures might have adverse effects on the survival of lactic acid bacteria, and the addition of L. rhamnosus to frozen foods at present is still not common (Castro et al., 1997; Fernandez Murga et al., 1998; Gilliland and Lara, 1988; Wang et al., 2005). Cell immobilization technology is a method using polymer, glass, inorganic salts, etc., to provide appropriate adsorption, binding, cross-linking, and entrapEnhancement of freezing-resistance of Lactobacillus rhamnosus by the application of cell immobilization