Antioxidant Properties of Ethiopian Traditional Bread (Injera) as Affected by Processing Techniques and Tef Grain (Eragrostis tef (Zucc.)) Varieties

The purpose of this study was to compare antioxidative potential of methanolic extracts of three tef grain (Eragrostis tef) varieties (white, brown and red tef) and their respective injera (pancakelike, soft, sour, circular flatbread and a staple food for majority of Ethiopians) and enriched one with fenugreek. Injera was prepared from dough fermented for 18 hours and 72 hours. The level of IC50 values of free radical and reducing power of various tef varieties varied from 0.6 to 0.88 mg/ml and 2.25 to 2.5 mg/ml respectively. The highest free radical scavenging activities (0.6 mg/ml) and reducing power (2.25 mg/ml) was observed in red tef while the lowest scavenging activities and reductive potential were shown in white tef (0.86 mg/ml) and (2.5g/ml), respectively. Total phenol content was higher in red tef (11.47 mg GAE/g) as compared to brown tef (9.72 mg GAE/g) and white tef (8.28 mg/ GAE/g). Total flavonoids for white, brown and red tef were 1.03 mg/CE/g, 1.78 mg CE/g and 2.13 mg CE/g, respectively. The phenol and flavonoid levels of three tef varieties were significantly affected (P<0.05) by processing. In all the four total antioxidants parameters, antioxidant activities of injeras decreased in the order of red tef injera > brown tef injera > white tef injera in the same processing conditions. The study showed that partly fermented tef injera (18 hrs of fermentation) had high antioxidant capacity than fully fermented tef injera (72 hrs of fermentation) among the same tef varieties. However, partly fermented tef injera extracts showed lower antioxidant activities than raw tef flour.