The viability of probiotic microorganisms may be affected if they are exposed to very acidic solutions. There was a greater reduction in the number of viable cells 1e2 h after exposure of the probiotic and symbiotic formulations containing pepsin to acidic condition at pH 1.5 as opposed to other acid solutions throughout the storage period (Tables 3 and 4). Viable cells of L. paracasei were greater than 8 log CFU/g throughout the storage period at pH 2.5 and pH 3.5 (Tables 3 and 4). These formulations maintained the number of viable cells above the minimum recommended (6 log CFU/g), demonstrating a great tolerance of the microorganism to high pH values. optimal growth temperature is usually at 37 C. However, studies with different species of the Lactobacillus genus verified that FOS favorably contributed to the continuous increase of viable probiotic cells during refrigerated storage of curd containing Lactobacillus acidophilus (Rodrigues et al., 2011), and fermented soy milk containing L. acidophilus, Lactobacillus plantarum, and Lactobacillus
rhamnosus