Effect of Fermentation on the Microbial, Proximate and Mineral Composition of Mung Bean (Vigna radiata)

Abstract

Aims: To examine the effect of fermentation on the microbial, proximate and mineral composition of mung bean. Study Design: Mung bean seed were obtained from local farmers in Ondo State, Nigeria. Unfermented sample was used as positive control. The study was carried out in the research laboratory, Federal University of Technology, Akure, Nigeria between December, 2012 and March, 2013. Methodology: The bean was divided into two portions A and B. Portion A was fermented for 7 days and B was analyzed raw. The physiochemical, microbial, proximate and mineral properties of the fermented sample were monitored during the period of fermentation. Results: The pH decreased significantly from 6.87 at 0 hour to 4.73 at 96 hours of fermentation and increased to 6.10 at 168 hours. There was also significant increase in total titratable acidity (TTA) value. There was a progressive significant increase in the bacteria count from 2.0x108 cfu/g to 2.5x108 cfu/g and significant decrease to 5.5x107 cfu/g on the last day. The fungi populations also increased from 2.8x104 sfu/g to 9.6x105 cfu/g as fermentation progressed. Seven bacteria viz; Staphylococcus aureus, Bacillus coagulans, Bacillus licheniformis, Bacillus subtilis, Bacillus megaterium, Leuconostoc mesenteroides, and Lactobaillus plantarum were isolated. Four fungi namely: Aspergillus niger, Aspergillus flavus, Penicillium italicum and Saccharomyces cerevisae were also isolated. The proximate analysis revealed that there was significant increase in the moisture content from 4.81 to 8.94%, a slight increase in protein content from 25.45 to 25.63% and a significant reduction in the carbohydrate content from 51.82 to 48.95%. The mineral composition (mg/g) such as potassium increased significantly from 17.35 to 25.59%, zinc from 0.74 to 0.79% and calcium from 2.49 to 3.27%. Conclusion: The proximate and mineral compositions as observed in the results suggest that fermentation may significantly improve the nutritional value of mung bean.