Original article Effect of grain tef [Eragrostis tef (Zucc.) Trotter] flour substitution with flaxseed on quality and functionality of injera Tewodros Girma, 1 Geremew Bultosa 1,3 * & Negussie Bussa 2 1 Department of Food Science and Postharvest Technology, Haramaya University, P.O. Box 138, Dire Dawa, Haramaya, Ethiopia 2 Medical Faculty, Haramaya University, P.O. Box 138, Dire Dawa, Haramaya, Ethiopia 3 Department of Food Science and Technology, Botswana College of Agriculture, Post Bag 0027, Gaborone, Botswana (Received 18 December 2011; Accepted in revised form 20 July 2012) Summary Injera from tef substituted with two flaxseed forms at 3%, 6% and 9% and control injera showed substi- tution had a significant effect on injera proximate, energy, titratable acidity (TA), total phenolics (TP) contents and sensory acceptability. Flaxseed forms had influence on moisture, fibre, total carbohydrate (TC) and TA. With 9% flour and whole flaxseed substitution, percentage energy, moisture, ash, crude protein, fibre and TA increase were 3.5, 27.3, 25.9, 20.4, 114.3 and 10.1, respectively. TC and pH were high for control. In all injera samples, condensed tannins and free fatty acid were insignificant. With an increase in the flaxseed substitution, most sensory acceptance increased, whereas injera eyes and colour decreased and appeared superior for control (100% tef injera). The 9% flaxseed-substituted injera showed good proximate nutritional and energy contents of functional potential of high in dietary fibre, alpha lino- lenic acid, lignans, proteins and TP of anti-oxidant nature. Keywords Energy, proximate, sensory acceptability, tef–flaxseed injera, total phenolics. Introduction Injera is the staple Ethiopian fermented bread pro- cessed from grain tef [Eragrostis tef (Zucc.) Trotter] flour. Tef is known to have better nutritional value than common cereal grains (wheat, barley, sorghum, maize and rice) because grain tef is always consumed as whole grain (Bultosa & Taylor, 2004). Grain tef bears about 11% protein, 73% carbohydrate (virtually all starch), 3% crude fibre (CF), 2.5% fat and 2.8% ash (Bultosa & Taylor, 2004). The very small size grain tef starch granules (2–6 lm) are implicated to have a fat mimetic, flavour and aroma carrier functionalities as that of small starch granules (Bultosa & Taylor, 2004). On fermentation for injera baking, about 9% of starch is known to be utilised by fermenting micro- organisms (Parker et al., 1989). Tef grain micronutrient is regarded high particularly in iron partly because of agronomic practices used in tef productions, and tef is usually consumed as injera in which mineral inhibitors like phytates are reduced on fermentation (Abebe et al., 2007). Grain tef is rich with digestible-type pro- teins, and the essential amino acid profile is regarded as well balanced when compared to FAO reference pattern (FAO/WHO, 1973) except lysine (Bultosa & Taylor, 2004). Grain tef is recommended as functional food for celiac patients (Bergamo et al., 2011), because it is gluten-free and offers in many respects more nutri- ent supply as it is consumed as whole grain often fer- mented as injera. Flax (Linum usitatissimum L.) is a perennial plant that has been used for centuries as food ingredient with health benefits because of its soluble fibre, lign- ans, high alpha linolenic acid (ALA, x-3 fatty acid) (Hall et al., 2005; Barbary et al., 2010) and proteins (Rabetafika et al., 2011). Whole grain, oil, milled or ground flaxseed forms are incorporated into diet (Truan et al., 2010) and also used as bakery ingredi- ents (Rabetafika et al., 2011). In Ethiopia, whole or crushed flaxseed is included in bread or breakfast cere- als as a healthy component and also it is consumed as roasted in stews, porridge or drinks. Cereal grains are somewhat limited in proteins, fats, some minerals and vitamins compared with animal- based foods and also in some essential fatty acids com- pared with oil seeds. Blending of the two types of grains makes a nutritionally better food than does either alone. Fermentation of cereals (Blandino et al., 2003) and their blend with oil seeds (Pohjanheimo et al., 2006) are potentially important and can improve the nutritive value such as proteins and essential fatty acids (poly unsaturated fatty acid, PUFA). It can also *Correspondent: E-mail: bultosageremew@yahoo.com International Journal of Food Science and Technology 2013, 48, 350–356 doi:10.1111/j.1365-2621.2012.03194.x © 2012 The Authors. International Journal of Food Science and Technology © 2012 Institute of Food Science and Technology 350