Determination of probiotic properties of lactic acid bacteria and yeasts isolated from three lacto‐fermented cereals mixed with whey, citrus, and tomato pomace

Abstract

This study tested the probiotic activities of bacteria and yeast isolates from three lacto-fermented cereal (LFC) products which were earlier shown high probiotic efficacy in farm animals. LFC products were freshly produced by solid-state fermentation using fresh whey without a starter culture. LFCa is a mixture of barley, whey, citrus pomace, LFCb of rye, whey, citrus pomace, and tomato pomace and LFCc of LFCb with an addition of ground thyme leaves at the end of fermentation. Six bacteria and two yeast species were isolated from LFC products and tested for probiotic activities. Candida spp and Saccharomyces spp exhibited low probiotic activities. However, lactic acid bacteria (LAB) isolates, namely, Lactobacillus plantarum O33, Pediococcus pentosaceus 10, Lactobacillus paracasei spp. paracasei O54, Enterococcus spp., Lactococcus lactis spp. lactis O3, and Lactobacillus curvatus O32 had overall high survival rates of 76% at pH 4.0, 95% at pH 5.0, 70% at 0.30% of bile salt, high exopolysaccharide production of 85 to 150 mg/L, acceptable aggregation rates of 19% of 4 h co-aggregation with E. coli and 25% auto-aggregation, high inhibition zones of 11 to 20 mm in diameter of pathogens and resistance to three antibiotics. Multivariate tests showed that Enterococcus spp. was the one with the highest probiotic efficacy. In conclusion, these LFC products can be used as probiotic supplements. Novelty impact statement This study determined the probiotic activity of bacteria and yeasts isolated from lacto-fermented cereals, previously shown to have high efficacy in animal studies. Yeast isolates exhibited low probiotic abilities, while six lactic acid bacteria isolated exhibited strong probiotic properties. Enterococcus spp. was found with the highest probiotic activities. The results showed that the products or isolated bacteria strains can safely be used in food and feed applications for health benefits.