Studying the effect of soymilk on survival of lactobacillus acidophilus in probiotic yoghurt drink

Prebiotics are defined as non-digestible food ingredients that benefit their hosts by selective stimulation of growth or activity of one or limited number of bacteria in gut. Probiotic products, when administered in adequate amounts, by improving internal microflora of body, confer an effective influence on the host from nutritional and health view. Consuming synbiotic products (simultaneous presence of probiotics and prebiotics) has more beneficial effects on consumer's health. In this study effects of replacing soymilk with milk (as a product containing prebiotics) in 3 levels, 0, 30 and 50% (w/w) on the survival of lactobacillus acidophilus, during storage of probiotic yoghurt drink were studied. Statistical analysis showed that replacing soy milk, resulted in significant increase (P<0.05) in total count of live probiotic bacteria in comparison to control samples and score of flavour is decreased by increasing of soymilk in formulation. Generally in all samples, during storage period, total count of live probiotic bacteria, pH and acceptability of flavor decreased, while acidity increased. All samples obtained the least required number of live probiotics according to FIL/IDF standard (6 log CFU/g).