Supplementation of Spirulina (Arthrospira fusiformis) and Oyster Mushroom (Pleurotus ostreatus) at Different Fermentation Stages of Injera, an Ethiopian Fermented Flatbread, Influences Its Nutritional Content, Antioxidant Properties, and Sensory Characteristics

Abstract

For most Ethiopians, injera is a staple diet, and it is a soft, circular, sour, fermented flat bread that resembles a pancake and is mostly made from teff (Eragrostis tef) and other grains. This study is aimed at evaluating the impact of adding spirulina (Arthrospira fusiformis) and oyster mushrooms (Pleurotus ostreatus) in the three stages of injera fermentation. After baking, the proximate composition, fatty acid profile, mineral analysis, and antioxidant properties were determined. The sensory evaluation of the injera was performed via a 5-point hedonic measurement. Compared with the 7-day fermented and unfermented injera, the 2-day fermented injera with algae and mushrooms contained more protein (119% to 142% increase) and total lipids (30% to 77% increase). Compared with their unfermented and 7-day fermented counterparts, the mushrooms and algae fermented for 2 days presented greater concentrations of methyl esters of pentadecanoic acid, 14-methyl-, 9-octadecenoic acid (Z)-, and 9,12-octadecadienoic acid (Z, Z)-. The percentage of inhibition of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical was lower in the methanol extracts of the injera that contained unfermented supplements (39%–43%) than in the methanol extracts of the injera that contained 2- or 7-day fermented supplements (73–77%). The injeras that contained only algae (E4, E7, and E10) were selected as their primary choice by the panelists. Adding supplements such as algae and oysters to the injera increased the nutritional content of the injera.