Effect of Oromo Dinich (Plectranthus edulis) flour supplemented on quality characteristics of teff-maize composite injera

Blending Oromo dinich flours with cereals-based flours significantly enhances the nutritional potential of cereals-based products. Therefore, this study aimed to develop and evaluate the quality of teff-based injera supplemented by underutilized indigenous tuber Oromo dinich (Plectranthus edulis) and maize flours. Fourteen formulations were generated using D-optimal constrained mixture design with a range of maize (5–15%), Plectranthus edulis (5–15%), and teff (70–90%). Statistical evaluation and optimization were done using D-optimal mixture design expert software. The results showed that the supplementation of more Plectranthus edulis flour in the formulations indicated better improvements in terms of protein (10–10.8%), fat (2.4–2.8%), gross energy contents (380.7–391.9 kcal/100g), total phenolic content (8.6–15.8 mg GAE/g) and total antioxidant capacity (66.20–82.7%) at the concentration of 3.32 mg/mL. The sensory acceptability of the injera was significantly (p < 0.05) liked in terms of aroma with increasing the ratio of Plectranthus edulis and maize flours. The optimum value of the blending ratio was 77.6% teff, 13.1% maize, and 9.3% Plectranthus edulis flours with desirable nutritional composition of injera, which varied for protein (10.7–10.8%), fat (2.62–2.8%) and energy (388.3–391.9 kcal/100g) and overall acceptance (5.5–6.3) with the desirability of 0.66. The optimization results indicated that supplementing Plectranthus edulis flour up to 10% with teff-maize composite flours were acceptable in terms of nutritional composition and sensory quality. Thus, supplementing underutilized indigenous Plectranthus edulis tuber flour with teff-maize flours significantly enhanced the nutritional potential of injera products.