Increasing the folate content of tuber based foods using potentially probiotic lactic acid bacteria

It is known that certain lactic acid bacterial (LAB) strains can produce folates, a B-group vitamin that cannot be synthesized by humans and must be exogenously obtained. The aim of this study was to select folate-producing LAB and evaluate their probiotic characteristics in order to obtain a tuber-based food with elevated folate content. Several LAB strains were isolated from a traditional Andean fermented potato product tocosh and cultured in folate-free culture medium. Five folate-producing strains (29–138 ng/mL) were selected to ferment three Andean tubers (potato S. tuberosum spp. andigena, oca Oxalis tuberosa and papalisa Ullucus tuberosus). Sterile purees were inoculated and samples were collected at 0, 6 and 24 h of fermentation and after 28 days of cold storage. Cell growth, pH and total folate were determined. All selected strains were able to grow and produce folates in the substrates and two Lactobacillus sakei strains, CRL 2209 and CRL 2210, produced the highest folate concentrations (730–1484 ng/g after 24 h fermentation). These strains were selected to ferment potato substrates supplemented with amaranth (Amaranthus caudathus) and chia (Salvia hispanica) flour to increase the nutritional value. This addition increased folate synthesis in 89–95%. Furthermore, the ability to survive under simulated gastrointestinal conditions was evaluated and cell counts of the 5 strains remained above the recommended for a probiotic candidate (8.0 log CFU/mL). In conclusion, the selected LAB could be considered potentially probiotic strains and could be used to produce novel tuber based products with elevated folate concentrations. These products could also be used as novel food matrixes for the delivery of probiotic microorganisms.