ABSTRACT
Plants are rich sources of antimicrobial agents because they produce wide array of bioactive molecules. Locally fermented beverages are consumed in parts of Nigeria. The processing is mostly done by people with simple household utensils. This study was conducted to investigate the microbial load, nutrition composition and shelf life of locally fermented beverages.
Pennisetum glaucum (millet grains), Cyperus esculentus (tiger nut), Musa acuminata (banana) and Citrus sinensis (orange) were purchased from Oba market in Benin City, Edo State. One kilogram (1kg) of millet grains were cleaned and steeped in twice its volume of clean water (1:2 w/v) for 24 hr in a covered plastic bucket at ambient temperature. The steeped millet grains were washed and wet milled with the adjuncts (banana, orange and tiger nut) using a well cleaned disc attrition mill. Water was added to the extent that the mixture can be easily sieved to remove the chaffs, the slurry was left to settle for 4hrs and then the supernatant was decanted from the slurry and Saccharomyces cerevisiae was introduced. Bacterial and fungal were isolated and identified using cultural techniques. Elemental mineral composition and proximate analysis were carried out using standard methods.
Bacterial count of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 6.41 ± 5.38 x 104 to 8.51 ± 6.21 x 104 cfu/ml, 3.13 ± 3.18 x 104 to 4.08 ± 3.98 x 104 cfu/ml, 3.22 ± 3.43 x 104 to 3.86 ± 2.14 x 104 cfu/ml and 3.37 ± 3.45 x 104 to 3.92 ± 2.33 x 104 cfu/ml respectively. The fungi count of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 2.94 ± 3.33 x 103 to 3.82 ± 3.83 x 103 cfu/ml, 2.55 ± 4.02 x 103 to 3.59 ± 3.41 x 103 cfu/ml, 2.42 ± 3.08 x 103 to 3.42 ± 3.06 x 103 cfu/ml and 2.63 ± 3.11 x 103 to 3.64±3.12 x 103 cfu/ml respectively. Bacterial isolated from the different samples were Bacillus sp., Proteus sp., Staphylococcus aureus and Escherichia coli, while fungi isolated were Aspergillius niger, Fusarium sp. and Penicillium sp. The titratable acidity value of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 2.81 ± 0.41 to 4.03 ± 0.74 g/l, 3.72 ± 0.79 to 4.27 ± 0.87 g/l, 4.72 ± 1.21 to 5.42 ± 1.23 g/l and 3.46 ± 0.62 to 4.01 ± 0.81 g/l respectively. pH of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 2.01 ± 0.19 to 4.63 ± 0.42, 3.28 ± 0.40 4.72 ± 0.94, 5.88 ± 1.60 to 4.20 ± 1.13 and 4.55 ± 0.42 to 3.01 ± 0.10. Protein content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 2.34 ± 0.37 to 1.50 ± 0.02 %, 3.55 ± 1.63 to 2.86 ± 0.46 %, 3.60 ± 1.51 to 2.99 ± 0.58 % and 3.54 ± 1.42 to 2.98 ± 0.60 % respectively. Carbohydrate content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 3.01 ± 0.36 to 2.51 ± 0.30 %, 4.67 ± 1.05 to 4.12 ± 1.23 %, 4.52 ± 1.13 to 4.00 ± 1.19 % and 4.33 ± 1.09 to 3.95 ± 1.10 % respectively. Lipid content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 9.60 ± 1.18 to 6.11 ± 1.00 %, 11.32 ± 2.12 to 8.42 ± 1.09 %, 11.09 ± 2.03 to 8.18 ± 1.19 % and 11.17 ± 2.04 to 8.27 ± 1.17 % respectively. Iron content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 20.07 ± 0.64 to 16.82 ± 0.51 mg/kg, 24.23 ± 2.34 to 18.69 ± 0.44 mg/kg, 24.58 ± 2.17 to 19.00 ± 0.26 mg/kg and 24.61 ± 2.54 to 18.78 ± 0.3 mg/kg respectively. Calcium content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 12.30 ± 3.52 to 10.04 ± 2.11 mg/kg, 15.32 ± 3.23 to 11.09 ± 2.04 mg/kg, 15.02 ± 3.10 to 11.01 ± 2.12 mg/kg and 15.48 ± 3.22 to 11.20 ± 2.09 mg/kg respectively. Zinc content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 19.51 ± 0.45 to 15.26 ± 0.21 mg/kg, 21.26 ± 1.38 to 19.09 ± 0.63 mg/kg, 21.52 ± 1.45 to 18.90 ± 0.45 mg/kg and 21.60 ± 1.56 to 19.18 ± 0.89 mg/kg respectively. Magnesium content of the control sample, formulated millet beers with tiger nut, banana and orange adjunct ranged from 29.94 ± 0.12 to 26.27 ± 0.34 mg/kg, 31.42 ± 1.33 to 29.11 ± 1.42 mg/kg, 31.46 ± 1.28 to 28.75 ± 1.02 mg/kg and 31.23 ± 1.52 to 29.23 ± 1.34 mg/kg respectively. This study suggest that more research should focus on the shelf stability and optimization of storage conditions of formulated millet beer, now that there is an emerging and increasing interest in probiotic products of non-dairy sources.
