314 CEREAL CHEMISTRY Effects of Sorghum Cultivar on Injera Quality Senayit Yetneberk, 1,2 Henriette L. de Kock, 2 Lloyd W. Rooney, 3 and John R. N. Taylor 2,4 ABSTRACT Cereal Chem. 81(3):314–321 Injera is an Ethiopian flat bread made from cereals, with tef preferred for the best quality injera. Because sorghum is less expensive in Ethiopia, there is great interest in improving the quality of sorghum injera. Effects of cultivar on injera quality were studied using 12 Ethiopian sorghum cultivars of varying kernel characteristics. White tef with good injera making quality was included as a reference. Injera quality was evaluated using two techniques: descriptive sensory analysis of fresh injera and instrumental texture analysis of injera stored over a storage period of 48 hr using a three-point bending rig. Principal component analysis (PCA) of sensory data associated fresh injera from sorghum cultivars 3443-2-op, 76TI #23, and PGRC/E #69349 of varying endosperm texture, with positive injera texture attributes of softness, rollability, and fluffiness. Across the two seasons, texture analysis showed injera prepared from AW and CR:35:5, both with soft endosperm, required the least force to bend after 48 hr of storage. Bending force was negatively correlated with softness (r = –0.63, P < 0.05) and positively with grittiness (r = 0.75, P < 0.01) after 48 hr of storage. Sorghum cultivar has an influence on both injera making and keeping qualities. Injera is a leavened, flat round Ethiopian traditional bread made from cereals such as tef and sorghum (Gebrekidan and GebreHiwot 1982). Its surface has essentially evenly spaced gas holes, that make up a honeycomb-like structure formed due to the production of gas during fermentation and baking. The bottom surface of injera is smooth and shiny. A good injera is soft, fluffy and able to be rolled without cracking. It should retain these textural properties after two to three days of storage, which is tra- ditionally done in a straw basket. A slight sourness is a char- acteristic taste of injera. Because injera is a leavened bread made from nongluten containing flour, it has great potential for com- mercial production internationally. Injera prepared from flour of tef [Eragrostis tef (Zucc.) Trotter], a tiny, millet like grain, is the most preferred. The annual pro- duction of tef in Ethiopia is about 1.32 million metric tons (Central Statistical Authority 1998). Of note is the fact that tef commands a higher market price than other cereals in Ethiopia (Seyfu 1993). Sorghum (Sorghum bicolor (L.) Moench) is the second most preferred cereal for injera preparation in Ethiopia (Gebrekidan and GebreHiwot 1982) with an annual grain production of 1.34 million metric tons (FAO 2001). Preparing injera from sorghum has con- siderable economic benefits over tef, as sorghum commands a much lower price. However, the problem is that sorghum injera rapidly becomes firm and friable upon storage. Gebrekidan and GebreHiwot (1982) reported that sorghum cul- tivar differences existed for injera making quality and staling. Yetneberk and Adnew (1985) developed a standard procedure for sorghum injera preparation and used it to evaluate the injera making qualities of different sorghum cultivars obtained from the Ethiopian Sorghum Improvement Program. They confirmed the existence of sorghum cultivar differences for injera making quality. It has also been found that the use of composite flour of sorghum and tef improved injera texture compared with 100% sorghum (Gebrekidan and GebreHiwot 1982; Yetneberk and Haile 1992). Zegeye (1997) conducted a consumer preference sensory test of injera from different cereals and reported that sorghum was accepted as a substitute for tef in injera preparation. The above studies indicate that sorghum cultivar does have an influence on injera making and keeping qualities. Thus sorghum cultivars with improved injera making quality could probably be selected on the basis of positive injera quality attributes. How- ever, previous researchers (Gebrekidan and GebreHiwot 1982; Yetneberk and Haile 1992; Zegeye 1997) used consumer sensory methods to evaluate sorghum injera making qualities. The use of descriptive sensory analysis and instrumental textural analysis to quantitatively evaluate injera quality has not been reported. Des- criptive sensory analysis detects, identifies, describes, and quantifies attribute differences between products and gives information on how raw material and process variables affect sensory charac- teristics (Stone and Sidel 1985). The objective of the present study was to determine the influ- ence of sorghum cultivar on injera making and keeping quality using descriptive sensory analysis and texture analysis with a view to objectively evaluate sorghum cultivars for selection in sorghum breeding. A wide range of Ethiopian lowland sorghums was used and compared with a white tef cultivar of known good injera making quality. MATERIALS AND METHODS Materials Twelve sorghum cultivars (IS-777, A ligider Wodifereja [AW], PGRC/E #69441, Seredo, CR:35:5, 3443-2-op, SK-82-022, 76TI #23, Gambella 1107, PGRC/E #69349, [(SC-423xCS-3541)-2- 1xRS/R-20-8614-2] [SC-423], [(SC-108-3xCS-3541)-19-1xRS/R- 20-8614-2)] [SC-108]) grown in both the 1999 and 2000 crop years at the Melkassa Agricultural Research Center, Nazareth, Ethiopia, were used. These cultivars had different endosperm texture and pericarp color. Seven were white tannin-free, one red tannin-free, and four tannin types as indicated by presence of pigmented testa in the latter (Table I). The cultivars are adapted for cultivation in the low- land (high temperature, erratic rainfall) areas of Ethiopia. A white tef cultivar DZ-01-196 with excellent injera making quality, grown in 1999 and 2000 at the Debre Zeit Research Center, Ethiopia, was included for comparison. All sorghum grains were decorticated to ≈80% extraction rate using an abrasive rice pearler (Miag, Braun- schweig, Germany) milled to flour using a hammer mill (3100, Falling Number, Huddinge, Sweden) fitted with a 500-μm screen. Tef was not dehulled before milling. Kernel Characterization Sorghum grains were characterized visually for pericarp and endosperm color by comparing with color plates (Rooney and Miller 1982). Glume color was determined by examining the inside of the glume after removing the kernel as described by Rooney and Miller (1982). Pericarp thickness was subjectively rated as thin, intermediate, and thick by scraping through the pericarp with 1 Food Science Research Division, Melkassa Agricultural Research Center, P.O. Box 436, Melkassa, Ethiopia. 2 Department of Food Science, University of Pretoria, Pretoria 0002, South Africa. 3 Cereal Quality Laboratory, Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843-2474. 4 Corresponding author. Phone: +27 12 420 4296. Fax +27 12 420 2839. E-mail: jtaylor@postino.up.ac.za Publication no. C-2004-0310-03R. © 2004 American Association of Cereal Chemists, Inc.