Assessment of Preservative Ability of Aqueous and Ethanolic Extracts of Onion (Allium cepa L ) on Soybean Daddawa- A Condiment

Abstract

Reports have indicated that lipid peroxidation is a key factor in soybean daddawa deterioration and Alliums are rich in antioxidants. The present study was carried out to investigate the preservative abilities of aqueous and ethanolic extracts of Onion (Allium cepa L) on stored soybean daddawa compared with Sodium Chloride treated samples. Soybean (Glycine max (L). Merr.) seeds fermented into soybean daddawa was preserved with both extracts (at 3, 5 and 7% concentration) and NaCl (at the concentrations of 0, 3 and 5%). The samples stored at 30±2°C for up to 14 days were analyzed for peroxide value (POV), free fatty acid (FFA), pH, titratable acidity (TTA), water absorption capacity (WAC) and fat absorption capacity (FAC). Type of solvent used in extraction did not have significant effect on all the storage indices. Extracts of Onion significantly lowered the POV, FFA and TTA generated in stored soybean daddawa. The pH of stored soybean daddawa samples treated with the NaCl and aqueous extract was not significantly affected while the ethanolic extract significantly reduced the pH from 8.26 – 8.34 to 5.72 – 5.89. The tested extracts lowered the WAC significantly while the FAC of treated soybean daddawa was not significantly affected compared to those treated with NaCl. Results of this study indicate that both extracts of Onion are more effective in lowering peroxidation in stored soybean daddawa and thus could be exploited for soybean daddawa preservation.