Abstract
Isolation and characterisation of Lactic Acid Bacteria (LAB) associated with the fermentation of maize and sorghum for the production of ogi were evaluated for the development of starter cultures. Changes in pH and LAB counts were investigated during the cereal based-product fermentation. A decrease in pH was observed during the natural fermentation from 0hr to 48hrs. The LAB were isolated, characterised and identified using cultural, morphological and physiological methods. The isolates were: Lactobacillus plantarum, Lactococcus lactis, Lactobacillus acidophilus, Lactobacillus cellobiosus, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus casei. The isolates from maize–produced ogi were capable of growing on sterilised maize grains, with Lactobacillus plantarum having the highest potential as a starter culture for ogi production from maize. Also, the isolates from sorghum-produced ogi were capable of growing on sterilised sorghum grains, with Lactobacillus delbrueckii subsp. bulgaricus having the higher potential as starter culture for ogi production from sorghum. Sterilised maize grains inoculated with pure culture of Lactobacillus plantarum showed the highest counts of 2.1 × 108 at 24 hrs of fermentation than the other Lactic Acid Bacteria. In the same vein, sterilised sorghum grains inoculated with pure culture of Lactobacillus delbrueckii subsp. bulgaricus showed the higher counts of 1.12 × 108 at 24 hrs of fermentation than the other Lactic Acid Bacterium. There was no significant difference (p ≤ 0.05) in the mean of the pH values obtained during the spontaneous fermentation of maize and sorghum. The results obtained indicated that all the six LAB isolates could be used singly as starter cultures to produce ogi within a shorter fermentation period.
Highlights
Microorganisms have been used to produce food for thousands of years
Sterilised maize grains inoculated with pure culture of Lactobacillus plantarum showed the highest counts of 2.1 × 108 at 24 hrs of fermentation than the other Lactic Acid Bacteria
In the same vein, sterilised sorghum grains inoculated with pure culture of Lactobacillus delbrueckii subsp. bulgaricus showed the higher counts of 1.12 × 108 at 24 hrs of fermentation than the other Lactic Acid Bacterium (Table 13 & 14)
Summary
Microorganisms have been used to produce food for thousands of years. Lactic acid bacteria constitute an important group of these organisms and have been associated with production of fermented foods and feeds for many centuries [1]. Some of the reasons for their widespread use are the ability to retard spoilage, preserve food as well as improve flavour and texture of foods They play fundamental role in microbial ecology of foods by synthesizing a variety of antimicrobial compounds such as organic acids, hydrogen peroxide, diacetyl and bacteriocins [2,3]. They are increasingly being recognised for their health and nutritional benefits, some strains are used as probiotics [4,5,6,7].
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