PRODUCTION AND CHARACTERISTICS OF NON-DAIRY PROBIOTIC DRINKS FROM SOYBEAN (GLYCINE MAX L.) AND TIGERNUT (CYPERUS ESCULENTUS L.)

Abstract

Probiotic foods are functional foods which provide healthy benefit beyond nutrition. In this study, non-dairy probiotic drinks were produced from tigernut extracts and soymilk. In the production of this probiotic drinks, fresh tigernut and soybean were, evaluated microbiologically, physically and chemically. Afterwards, isolated microorganisms were characterized and identified using standard methods. Isolates identified as Lactic acid bacteria (LAB) were further screened for their probiotic potential, LAB with the best probiotic properties were used in the production of non-dairy probiotic drinks following standard methods. The effect of probiotication on the physicochemical, nutritional and antinutritional composition of soymilk and tigernut milk were determined, and the probiotic drinks were evaluated for their sensory properties and shelflife stability, the viability of the probiotics in the drinks was also monitored. Generally, sixty five (65) microorganisms were isolated from soybeans and tigernut of which 40 (61.54%) were bacteria and 25 (38.46%) were fungi. The species of bacteria isolated from the samples include; Bacillus subtilis, Staphylococcus aureus, Lactobacillus fermentum, Lactobacillus plantarum, Micococcus luteus, Listeria monocytogeness, Serratia spp, Proteus vulgaris, Escherichia coli and Lactobacillus casei. Similarly, the species of fungi isolated were Aspergillus niger, Saccharomyces cereviseae, Candida tropicalis, Mucor mucedo, Penicillium chrysogenum and Aspergillus flavus. Two out of the three LABs isolated which showed good probiotic properties were molecularly identified as Lactobacillus fermentum and Lactobacillus plantarum. Probiotication of the drinks with the two probiotics resulted in the reduction of the pH of the drinks, and consequentially increased its total titratable acidity (TTA). The antinutrients content of the drinks reduced, whereas, the antioxidant property and mineral content of the drinks increased. It was also observed that the probioticated drinks had a higher score for all the sensory attributes which made them to compare favourably with the dairy yogurt as against their unprobioticated counterpart. Generally, the overall acceptability of the probioticated drinks prepared was found to be above average. Refrigeration of the probioticated drinks supported and maintained the growth and survival of the probiotic microorganisms throughout the storage period with minimal probiotic count of 3.40 x 107cfu/ml. Storage at ambient temperature did not maintain the growth and survival of the probiotics, as there were reduction in their count as the storage period increases most especially at week 4 and 5 where probiotics counts reduced to zero (0.00). This consequentially permits the growth of other spoilage microorganisms like Listeria monocytogens, Staphylococcus aureus, and some moulds in the drinks. In conclusion, results obtained from this research have shown that the milk extracted from soybean and tigernut and the probiotication process were sufficient to produce probioticated soymilk and tigernut milk that could compete with available probiotic drinks in the market