In vitro Probiotic Potential of Autochthonous Lactic Acid Bacteria and Microbiology of Kunu Made from Mixed Grains

Abstract

Aims: This study investigated the microbiological quality of commercially-prepared kunu in comparison with those prepared under laboratory conditions using two cereals, millet and sorghum, and the in vitro probiotic potential of the autochthonous lactic acid bacteria. Study Design: Randomized complete block design. Place and Duration of Study: Food Processing Laboratory, Food Science and Technology Department, Federal University of Technology, Akure, and Akure metropolis of Ondo State, Nigeria in June 2015. Methodology: Eight Kunu samples were used; 5 obtained from different commercial processors and 3 prepared in the laboratory from a combination of two cereal grains. The samples were subjected to physicochemical and microbiological analyses. Microorganisms isolated were characterized using conventional identification tests and the lactic acid bacteria were screened in vitro for their probiotic potential. Results: Crude protein (%dry weight) of samples ranged from 33.85-58.68%; with the sample prepared from a combination of sorghum and millet having the highest content. Total ash (3.84-6.26%) and solids (7.00-9.11%) varied significantly (P=0.05) between samples. Values obtained for pH and acidity of the samples ranged from 4.14-5.01 and 1.22-3.45%. Out of 13 microbes isolated from the Kunu samples, 6 were lactic acid bacteria, 2 Bacillus spp., 3 other bacteria, 1 mould and 1 yeast. Lactic acid bacteria identified include L. acidophilus, L. plantarum, Lactobacillus jensenii, Lactobacillus cellibiosus, Leuconostoc mesenteroides, Leuconostoc cremoris. Lactobacillus acidophilus was predominant and showed the most significant antimicrobial inhibition against all three pathogenic strains tested (Escherichia coli, Salmonella enterica subsp. typhi and Shigella dysenteriae), followed by Leuconostoc mesenteroides; L. plantarum and L. jensenii varied in their activity, while L. cellibiosus showed the least activity. The isolates showed high acid tolerance, out of which L. plantarum and L. acidophilus showed the highest tolerance. Conclusion: The selected lactic acid bacteria exhibited excellent probiotic characteristics and thus can serve as potential probiotics, hence indicating that spontaneously-fermented kunu can serve as a probiotic drink.