Abstract:
Ogi is a widely consumed food product but could possess low nutritional value when poorly
processed. Fermentation had been found to improve its nutritional value, sensory properties and
shelf life. However, information on fermentation of ogi using inocula from palm wine, burukutu
and yoghurt is sparse. This study was designed to investigate the effect of processing and selected
modified fermentation methods on quality attributes of sorghum ogi.
Based on preliminary studies, ogi was processed from unmalted, malted (germinated for 72 hours,
dried at 48oC for 24 hours) and milled sorghum using Spontaneous Fermentation (SF) method for
between 24 and 72 hours. These samples were subjected to sensory evaluation using panelists.
Ogi was also produced using sample with highest overall sensory score (control), and fermented
with each of palm wine, burukutu and yoghurt inocula (0.08– 0.12 µL/500mL) as starter culture.
Microorganism in SF samples, palm wine, burukutu, and yoghurt; Palm Wine Fermented
Sorghum (PWFS), Burukutu Fermented Sorghum (BFS) and Yoghurt Fermented Sorghum (YFS)
were cultured and isolated using ISO methods. Molecular characterisation of the isolates was
done by polymerase chain reaction sequencing. Chemical, physical, functional and pasting
properties, and in-vitro protein digestibility of samples were determined by AOAC methods.
Sensory properties of the products were determined using panelists. Data were analysed using
ANOVA at α0.05.
Ogi from unmalted-whole sorghum spontaneously fermented for 72 hours had lowest overall
acceptability of 5.51, while 48 hours spontaneous fermented malted-milled sorghum had highest
score of 7.34. Lactobacillus plantarium, Bacillus subtilis, and Lactobacillus lactis were dominant
in SF samples. Lactobacillus spp. were present in palm wine, burukutu, and yoghurt.
Lactobacillus, Leuconostoc, Bacillus, Streptococcus and Saccharomyces spp.; Lactobacillus,
Staphylococcus, Acetobacter, Weissella, Leuconostoc, Lactococcus, Bacillus and Saccharomyces
spp.; and Streptococcus, Lactobacillus, Bacillus, Micrococcus and Pseudomonas spp. were the
isolated organisms in PWFS, BFS and YFS, respectively. The concentrations of the inocula
significantly affected starter culture activities, with 0.1 µL/500 mL being appropriate.
Carbohydrate, protein, fibre and ash contents of the samples varied significantly. The SF sample
had least protein content of 5.7%, while YFS had highest protein of 10.3%. Potassium was the
dominant mineral in all the samples. The YFS sample had lowest tannin (0.08±0.01%), phytate
(0.08±0.01%) and oxalate (0.99±0.01%) contents. The L*, a* and b* colour values of samples
ranged from 51.27 to 65.66, 10.08 to13.27 and 11.35 to 18.79, respectively. The loose and packed
bulk density was 0.44-0.62 and 0.58-1.82 g/mL, respectively. Total titratable acidity ranged from
0.20 to 1.83 g/L and pH from 3.50 to 5.72. Spontaneously fermented samples had lowest pH. The
swelling power and solubility of samples was 3.11-7.20 and 0.03-2.04%, respectively.
Fermenting using starter culture significantly reduced peak viscosity of sorghum ogi with SF
samples being highest (126.83±2.59 RVU). Introduction of starter culture significantly increased
protein digestibility of sorghum ogi. The PWFS had highest overall acceptability score of 7.28.
Grain milling before fermentation and induced fermentation using palm wine, burukutu and
yoghurt inocula improved the nutritional properties of sorghum ogi and were recommended for
improving qualities of similar fermented food products.
