Feasibility study on co‐culture Bacillus coagulans and Lacticaseibacillus rhamnosus formulated in probiotic‐supplemented pigmented rice products

Based on testing inhibition to nine strains of pathogens in the gastrointestinal tract, Lacticaseibacillus rhamnosus KPS-VE9 inhibited the growth of Aeromonas hydrophila, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Serratia marcescens, Staphylococcus aureus, Vibrio parahaemolyticus, and Candida albicans, whereas Bacillus coagulans KPS-TF02 inhibited only V. parahaemolyticus when performed in brain–heart infusion agar. When these two strains of probiotics were tested using ABTS+ scavenging assay, B. coagulans KPS-TF02 and L. rhamnosus KPS-VE9 produced good levels of antioxidants, with their antioxidant activities at 1.50 and 2.00 mg Trolox equivalent/μl, respectively. B. coagulans KPS-TF02 survived well under simulated gastric and small intestine conditions with higher survival rates when the bacterium was mixed in rice-based carriers, whereas L. rhamnosus KPS-VE9 had a high survival rate only under simulated gastric conditions without rice. However, in probiotic rice products, the survival rate after storage at 4°C for 6 months was higher than that at 25°C for both probiotic strains, being only L. rhamnosus KPS-VE9 able to maintain counts higher than 106 CFU/g at the end of the storage period. No microbial contamination was observed for the rice capsules studied. The survival rates of the probiotics studied in the rice capsules when submitted to the simulated gastrointestinal conditions were, therefore, not directly correlated to their initial counts in these products. Novelty impact statement This is the first report of an application of mixed cultivars of Thai-pigmented rice and mixed culture probiotics as a novel dried-formulated probiotic product. This research investigated the probiotic properties of two probiotic bacteria (Bacillus coagulans KPS-TF02, and Lacticaseibacillus rhamnosus KPS-VE9) in developing novel probiotic products using Thai-pigmented rice (purple, red, and yellow color) as a carrier. Probiotics have antibacterial activity and show high antioxidant activities.