Applied Microbiology and Beneficial Microbes

Riboflavin (vitamin B2) is a crucial vitamin for metabolic processes such cell development, energy generation, and redox potential. The incorporation of probiotic strains with the potential to produce riboflavin and the development of functional foods such as fermented soymilk has huge societal importance. For process optimization of fermentation kinetics,the fermentation process of soymilk inoculated with different combinations(1%,2%,2% for each) of starter and probiotics cultures were analysed for parameters i.e., probiotic count and riboflavin count at different time intervals. For probiotic count, suitable amount of sample drawn at each time interval & serially diluted in sterile normal saline and suited dilutions were plated on MRS agar plates. 5 mL fermented soy-milk combined with an equivalent amount of acetic-acid (1%) was autoclaved at 121°C for 30 minutes. To evaluate riboflavin concentration, the samples were centrifuged at 10,000g for 15 minutes. For riboflavin estimation, 0.22 µm filters were used to filter the obtained supernatant (Merck, Germany). The High-performance liquid chromatography (HPLC) was used for analyzing the supernatant obtained from fermented soy-curd using a reverse-phase C18 column and fluorescence detector having excitation wavelength 440 nm and emission wavelength 520 nm. The samples were analysed using an isocratic elution technique with a flow rate of 1mL per min and a methanol/water (35:65v/v) mobile phase. As a control, pure riboflavin is used. The soymilk fermented with L. plantarum MTCC 25433(2%), L. plantarum MTCC 25432 (2%), and L. plantarum (2%) and L. acidophilus (2%) from standard dahi cultures showed maximum riboflavin production at 12 hours of incubation.