There is currently an emerging problem of protein malnutrition in Ethiopia. This food formulation was done to increase the accessibility of nutrient rich food products for the consumers. Lupine (Lupinus spp.) is a legume crop which is an excellent source of protein. The aim of this study was to investigate the effect of tef, lupine varieties and blending ratio on the chemical composition of injera and sensory acceptability of Ethiopians staple food. The effect of blending ratio and lupine varieties (Australian sweet lupine and Dibettered lupine seed) were studied. The formulations were generated by using mixture design software. Lupine variety and blending proportion had significant (P<0.05) effect on proximate, mineral and anti-nutritional compositions of blended injera. The nutritional compositions of formulated injera ranged from 60.37 to 66.97%, 1.76 to 2.05 %, 11.78 to 18.84 %, 2.53 to 4.01 %, 2.83 to 3.16%, 72.55 to 81.32% and 393.19 to 400.91 kcal/100g for moisture content, total ash, crude protein, crude fat, crude fiber, utilizable carbohydrate and gross energy, respectively. The result showed that the crude protein content highly increased as the proportion of lupines increased. Crude protein and crude fat contents were higher for injera blended with dibettered lupine seed variety while crude fiber content was higher for those blended with Australian sweet lupine variety because of the raw material. Mineral content of composite injeras varied from 12.26 to 14.98 mg/100g, 2.39 to 2.83 mg/100g, and 145.31 to 163.96 mg/100g for iron, zinc and calcium contents respectively. All three mineral contents were higher in tef blended with dibettered lupine seed variety. The Tannin and phytic acid contents ranged from 9.59 to 11.95mg/100g and 98.91 to 120.64 mg/100g, respectively. As the sensory acceptability scores data indicated for both lupine varieties blended with tef for the production of injeras of up to 15% lupines almost all sensory attributes showed higher scores without significantly different among them but after 15% lupine addition there were observed drop of the sensory acceptability scores. In a 7 point hedonic scale, the composite sample tef injeras with 10% dibettered lupine seed variety addition had the highest scores of 6.09, 6.22, 6.09 and 6.18 in eye size, aroma, rollability and overall acceptability respectively. Therefore, this study showed significant increment in protein content of injera and provides insights for use of lupine-tef flour mixture at home and industry level for enriched injera.
Keywords: Anti-nutritional factors, Australian sweet lupine, Composite injera, Dibettered lupine seed, nutritional composition, minerals