Microbiological properties, anti-nutritional and nutritional composition of spontaneously and starter culture fermented malted acha flour

Nutrients can be made bioavailable in foods through fermentation of such foods either spontaneously or via starter cultures with consequent reduction in antinutrients. The effect of fermentation time on the microbiological properties, anti-nutritional and nutritional contents of malted acha (Digitaria exilis) flour fermented spontaneously and using starter culture was studied. Malted acha flour was fermented spontaneously and using starter culture for 72 and 48 h respectively. Two screened lactic acid bacteria with the best probiotic potential were employed from 11 bacteria isolates after they were identified using molecular method. Microbiological, antinutritional and nutritional analyses of the fermented products was performed using standard methods. There were decreases in aerobic bacteria and lactic acid bacteria counts after 72 h fermentation period with a converse increase in yeast count of the fermenting slurry during the same period. For spontaneously fermented acha flour, increases in values at P < 0.05 were recorded for crude protein (9.67 +/- 0.03 to 10.80 +/- 0.06%), crude fat (1.07 +/- 0.03 to 1.23 +/- 0.03%), moisture content (8.47 +/- 0.09 to 8.53 +/- 0.07%), and ash content (1.30 +/- 0.06 to 1.37 +/- 0.09%), within 48 h fermentation time and decreased by 72 h. Also, the mineral and vitamin contents increased with increase with fermentation time. However, decreases in values were recorded for carbohydrate content (77.30 +/- 0.06 to 76.30 +/- 0.11%) and crude fibre (2.20 +/- 0.06 to 1.73 +/- 0.03%) at 48 h and 72 h fermentation time respectively. The pH and antinutritional factors decreased with increase in fermentation time while the titratable acidity decreased. For starter culture fermentation, sample J which consist of the blend fermented with single starter (Lactobacillus plantarum), gave the highest yield for crude fat and moisture content (8.77 +/- 0.09%) after 48 h fermentation period. The bioavailability of nutrients in the acha flour increased with fermentation time compared to the unfermented flour at 0 h fermentation time at P < 0.05. Starter fermentation of acha flour with lactic acid bacteria can be used to improve the proximate composition of acha flour which can be utilized as breakfast cereal.