Development of a Soy-Based Synbiotic Beverage

Abstract

Nowadays consumers seek foods that not only provide basic nutrition but also contain compounds that contribute to health. Thus, different products have been designed to meet this demand, especially those with probiotic and prebiotic characteristics. This study aimed to evaluate different formulations of a soy-based synbiotic beverage. The composition and process conditions were defined using a Placket & Burman factorial design in which the independent variables were process temperature, concentrations of the soy hydrosoluble extract and fructooligosaccharides (FOS) and the initial concentration of the probiotics Bifidobaterium longum, Lactobacillus acidophilus, Lactobacillus paracasei subsp. Paracasei, Lactobacillus rhamnosus. Changes to the product by addition of sucrose, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus were also studied. Response parameters were: pH, cell concentration (plate counting), and quantification of fructooligosaccharides, acetic acid and lactic acid. The specific growth rate (μ x ) and change in cell count (Δx) were determined in each formulation. The soybean hydrosoluble extract was considered a good substrate for beverage production; FOS had a greater effect at lower concentrations. At the end of all fermentation tests the total probiotic count was greater than 7 log CFU/mL, meeting the legal requirements of a functional food. Lower temperatures were better for the growth of probiotics. The addition of sucrose resulted in a lower consumption of FOS by the fermenting microorganisms, while the presence of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus represented little change concerning the evaluated characteristics. Therefore, according to the results of this study, the production of a soy-based symbiotic fermented beverage can be performed using soybean hydrosoluble extract at 10% (w/v), fructooligosaccharides at about 3% (w/v), sucrose at 12% (w/v), and the process temperature should be maintained at 35℃. Initial probiotic concentrations need not exceed 5 × 10 6 CFU/ml.