Evaluation of Preservative Efficacy of Aqueous and Ethanolic Extracts of Garlic (Allium sativum L.) on Soybean Daddawa – A Condiment

Abstract

On the understanding that lipid peroxidation is a key factor in soybean daddawa deterioration and Alliums are rich in antioxidants, this study was carried out to investigate the preservative efficacies of aqueous and ethanolic extracts of garlic on stored soybean daddawa compared with common salt (sodium chloride). Soybean (Glycine max (L). Merr.). Seeds fermented into soybean daddawa were preserved with both extracts (at 3, 5 and 7% concentration) and NaCl (at the concentrations of 0, 3 and 5%). All samples were stored at 30±20 C for 14 days and analysed for peroxide value (POV) (meq/kg of extracted oil), free fatty acid (FFA) (% oleic acid), pH, titratable acidity (TTA) ((mg lactic acid per g)), water absorption capacity (WAC) (%) and fat absorption capacity (FAC)(g/ml). The POV of stored daddawa without preservative (0 % NaCl) increased from 3.92 to 17.00 while those of sodium chloride treated daddawa increased from 3.70 to 12.20. On the contrary, in both garlic aqueous extract and garlic ethanolic extract treated daddawa, the POV range recorded at the end of storage were 4.17 – 4.20 and 4.92 – 5.80 respectively. Similarly, at the end of storage, a significantly (P<0.05) lower values of FFA (0.003 – 0.004) and TTA (0.040 – 0.067) were observed in garlic extract treated daddawa compared with 0.018 – 0.068 and 0.069 – 0.092 that were respectively obtained in control samples. Solvent used in extraction did not have significant (P>0.05) effect on all the storage quality indices. The pH of stored soybean daddawa samples treated with garlic extracts (7.99 – 8.74) was not significantly (P>0.05) different from both the positive (8.04 – 8.72) and negative (8.26 – 8.76) control treated daddawa. At the end of 14 days of storage, both the WAC (135 – 145) and FAC (0.6 – 0.7) of garlic extracts treated soybean daddawa were not significantly (P>0.05) different from 150 – 155 and 0.6 – 0.8 that were respectively observed in control samples. Results of the present study indicate that both garlic extracts could be considered as a probable alternative for preservation of soybean daddawa even at 3 % preservative  concentration.

Keywords: Antioxidant, garlic, NaCl, preservation, soybean daddawa