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| dc.contributor.author | Hilemichael, Wendu | |
| dc.date.accessioned | 2020-03-11T10:17:14Z | |
| dc.date.available | 2020-03-11T10:17:14Z | |
| dc.date.issued | 2020-03-11 | |
| dc.identifier.uri | http://hdl.handle.net/123456789/10216 | |
| dc.description.abstract | Injera, Ethiopian fermented bread, is made mainly from teff (Eragrostis teff). On average, two-third of Ethiopian diet consists of injera and it accounts for about two-thirds of the daily protein intake and has a high nutritional value, as it is rich in calcium, iron and zinc. Unfortunately, injera has a shelf life of only 3-4 days essentially due to mould (especially three fungal species Aspergillus niger, Penicillium sp and Rhizopus sp) spoilage. Nowadays, the use of plant extract as natural preservatives is increasing due to their antimicrobial activities, beside this they have high acceptability by consumers in regards to their health effect as well as their flavor and aroma improvement. In this research, the effect of aqueous and ethanolic extract of garlic, cinnamon, and clove on the shelf life of injera at different concentrations (2% ,5% and 10%) and different storage temperatures (30oC and ambient temperature (24±2oC)) were evaluated. The preservatives were added immediately before baking and their effect on shelf life (microbial quality) and sensory quality were analyzed. Sensory quality analysis was done using 5-point hedonic scale. For microbial analysis, total plate count and yeast & mould count were conducted. From the result obtained, the average sensory quality of the control was 4.4 followed by injera prepared from teff flour with addition of 2% aqueous extract of garlic and cinnamon with mean value of 4.2 and 4, respectivelly. Injera prepared from teff flour with addition of aqueous and ethanolic extract of clove shows the minimum over all acceptability, due to a bitter flavor of cloves cause by eugenol. Antimicrobial activities of the preservatives investigated could prolong the shelf life of injera up to 10 days at ambient storage temperature by using ethanolic extract of clove with 10% addition followed by 10% addition of aqueous extract of garlic which extend the shelf life of injera up to 8 days. At 30oC the maximum, shelf life of injera observed was 7 days by using ethanolic extract of clove and aqueous extract of garlic with 10% addition. In general, as the concentration of spices added increased, the sensory quality decreased whereas the microbial quality increased and the maximum shelf life of injera were observed at ambient temperature than 30oC | en_US |
| dc.language.iso | en | en_US |
| dc.subject | Chemical Engineering | en_US |
| dc.title | Improving Shelf Life of Injera by Using Natural Preservatives | en_US |
| dc.type | Thesis | en_US |
