ABSTRACT
Aims: A comparative study of fungi and bacteria fermentation of soybean (Glycine max) was carried out to determine the effect of fermentation on the nutritional composition of their fermented products: tempeh and ‘soy-iru’. Study Design: The experiment was carried out in the Department of Microbiology, Ekiti State University, Ado Ekiti, Nigeria, between August, 2017 and July 2018. Methodology: Soybean was processed into ‘soy-iru’ (bacterial fermentation) and tempeh (fungal fermentation) and the microbial load, physico-chemical properties, proximate composition, levels of anti-nutritional components (trypsin inhibitor and phytic acid), anti-oxidants (total phenol, total flavonoid and DPPH), in-vitro protein digestibility and vitamins (A, B, C, D, and E) were analyzed. Results: The microbial load, pH increased progressively during fermentation, while there was a decrease in the titratable acidity (TTA) of the two products. The protein(%), ash(%) and fat(%) contents of the Glycine max cotyledons increased from 29.56, 1.86 and 24.36 in unfermented substrate to 33.61, 2.21 and 26.90, respectively, after 24hrs of fermentation to produce tempeh. However, there was a reduction in the crude fibre(%) and carbohydrate(%) content from 2.94 and 41.29 in unfermented substrate to 2.53 and 32.57, respectively, after 24hrs of fermentation. Similar trends were observed during the production of ‘soy-iru’, however the change in proximate composition was not as significant as observed in tempeh. There was significant decrease in the trypsin inhibitor and phytic acid levels of the two products. The levels of anti-oxidants, vitamins B, D, E and protein digestibility increased significantly, in both bacterial and fungal-fermented products. Conclusion: This research has therefore shown that fungal fermentation of Glycine max seeds into tempeh may be a better alternative to ‘soy-iru’ which was obtained from bacterial fermentation, because of the significant lower level anti-nutritional factors in the former.
ABSTRACT
Bacillus spp. associated with two types of fermented African locust beans iru woro and iru pete were isolated and screened for probiotic potentials using standard microbiological techniques. The total bacterial counts for iru woro (pH 8.4) and iru pete (with pH 8.1) were 6.4314 and 6.4771 log10CFU/g respectively. In the two samples, the load of aerobic sporeformers were 6.2068 and 6.2553 log10CFU/g. In the samples Bacillus subtilis had the highest occurrence (44%), followed by B. lichenliformis (28%) and B. megaterium (24%) while B. coagulans had the least (4%). Only 28% of Bacillus isolates produced caseinase, while 28% produced haemolysin. Majority of these isolates showed tolerance to salt at concentrations less than 5% and also grew fairly at pH tending to neutral. Bacillus subtilis P14, Bacillus lichenliformis P12 and Bacillus megaterium P6 grew at 3.0% bile. Percentage hydophobicity, auto-aggregation and co-aggregation of the isolates ranged from - 49.00 to 65.00%, -53.00 to 84.00% and -69.44 to 36.08% respectively. High level of antibiotic resistance (especially to first line antibiotics) was recorded among isolates. Most of the Bacillus species isolated from the iru samples had very poor probiotic properties. Molecular and in vitro probiotic properties of promising candidates are still open to investigation.
ABSTRACT
Aim: Iru is a popular West Africa fermented soup condiment which is also consumed without cooking as snack. This product is mainly fermented by Bacillus species. The hypolipidemic activities of Bacillus spp. isolated from iru have not been documented hence the aim of this study. Place and Duration of Study: Iru sample was bought in an open market in Iworoko-Ekiti, Nigeria and transferred to the Laboratory of the Department of Microbiology, Ekiti State University, Nigeria where other studies were carried out. The study was conducted between January and June, 2012. Methodology: The properties and in vivo hypolipidemic potential of Bacillus species from iru were investigated using standard microbiological and haematological methods. Results: The cell free extracts of the Bacillus spp. did not produce significant inhibition on the selected Gram positive and Gram negative pathogens. Qualitative enzyme screening of the isolates showed all were haemolysin negative. Only B. subtilis was positive to gelatinase while all the isolates produced catalase and lipase. The average weight of the animals after inducement of hyper-cholesterolemia ranged between 60.5g - 95.3g. The amount of serum total cholesterol (TC) in the animals ranged between 124.9 mg/dl – 127.4 mg/dl while that of serum triglycerides (TG), high density protein (HDL) and low density protein (LDL) were 122.5 – 155.3 mg/dl, 10.0 – 15.3 mg/dl and 76.6 – 81.0 mg/dl respectively. The weights of hyper-cholesterolemia induced rats challenged with different species of Bacillus were relatively lower than those in the control group and also differ significantly from the control, at p˂ 0.05. The values of TC, TG, and LDL were highest in the control (saline) group while the values in the treatment group ranged between 121.3 ± 1.5 and 102.3 ± 6.8 mg/dl for TC. The treatment groups recorded lower values of values for TG (104.7 ± 1.6 - 117.4 ± 9.1 mg/dl) and LDL (42.6 ±7.4 - 59.0 ± 10.2 mg/dl) compared to the control. B. subtilis had the highest values of TC but least amount of LDL. TG in all the groups was higher than TC, HDL and LDL. The TC/HDL and the LDL/HDL of the animals in the iru group was higher than the other treatment groups but lower than the control. Conclusion: Compared to the control, hypolipidemic activities of B. lichenliformis was the best followed by B. subtilis. Iru had the least hypo-cholesterolemic effect.