Grain and Flour Quality of Ethiopian Sorghum in Respect of their Injera Making Potential EIAR Senayit Yetneberk, Lloyd W. Rooney, John R. N. Taylor and H.L. de Kock UP
Introduction Injera is an Ethiopian fermented leavened flat bread made from various cereal flours Sorghum injera (TI 76#23) It is characterized by having eyes (honeycomb-like holes) on its top surface
Introduction (continue) Tef is preferred for the best quality injera for softness and rollability Staling is a common problem to almost all baked products from sorghum Notwithstanding this, nearly 80% of the sorghum produced in Ethiopia is used for the production of injera (Gebrekidan and GebreHiwot, 1982)
Objectives 1. To confirm the role of grain quality in sorghum injera making 2. To determine the sorghum grain physicochemical factors involved in injera making quality 3. To establish objective indicators for rapid evaluation of sorghum cultivars in terms of injera making quality
Materials Twelve sorghum cultivars grown in two growing seasons at the Melkassa Agricultural Research Center, Ethiopia A white tef cultivar DZ-01-196 with excellent injera making quality is used for comparison o These cultivars had different endosperm texture and pericarp color o Four cultivars had pigmented testa
Measured parameters Kernel characterization Flour characterization Evaluation of injera quality attributes
Kernel characterization Thousand kernel weight (TKW) Glume color presence of a pigmented testa Pericarp thickness Endosperm texture
Kernel characterization (continues) Grain hardness using o Extraction rate using TADD mill o Endosperm corneousness by image analysis o Endosperm visual evaluation Test weight (hectolitre weight) Pericarp thickness image analysis
Flour characterization Water solubility index Water absorption index Pasting property Flour gel property
Evaluation of injera quality attributes A descriptive sensory analysis for objective measurements of the attributes of injera Instrumental texture analysis of fresh and stored injera o Over a storage period of 48 hrs using a three-point bending rig attachment
Endosperm corneousness (image analysis) Germ Germ PGRC/E Intermediate 69341 Germ Floury CR:35: 5 NOT SC-108 vitreouso More o Endosperm texture varied from floury to vitreous o Vitreous sorghum cultivar had a high extraction rate (89.7%) after abrasive decortication COPY
Differences in pericarp thickness (image analysis) al CR:35:5 SC-108 P P P Pericarp thickness ranged from thin to thick Pericarp thickness affects o o o Milling performance Flour quality Storage property
20 15 10 5 0-5 0 5 10 15 20 25 30 Double compression of sorghum and tef flour gel aged for 24 hrs at 4 C sorghum (76 TI#23). and tef (DZ 01 196) o The breaking point of sorghum flour gel was much lower compared to tef flour gel o Tef flour gel almost returned back to its undeformed condition
Steps in injera preparation Sorghum flour Mixing with water + addition of ersho Fermentation (48 hours) Gelatinization Second fermentation (2-3 hrs) Baking
PC 2: 26.48% 6 4 2 0 - -2-4 PGRC/E #69349 3443-2-op SC-423 Gambella 1107 76TI #23 SC-108 Tef SK-82-022 AW IS-777 CR:35:5 Seredo -6-6 -4-2 0 2 4 6 PC 1: 43.65% PGRC/E #69441 Plot of the first two principal component scores of the cultivars o Principal components (PCs) are orthogonal directions of maximum variance in the original data PC 2 : 26.48% 1.0 0.5 0.0-0.5-1.0 white-bs white-ts white-ts sweet-at sweet sweet eye eye eye eye eye eye eye eye dis dis dis dis dis dis dis dis eye eye eye eye eye eye eye eye even even even even even even even even shiny shiny shiny shiny shiny shiny shiny shiny gritty gritty gritty gritty fluffy eye eye eye eye size size size size eye eye eye eye size size size size bitter-at sour-at sour sticky bitter red-bs red-ts -1.0-0.5 0.0 0.5 1.0 rollable rollable rollable rollable rollable rollable rollable rollable soft soft soft soft soft soft soft soft Plot of the first two principal component loading vectors of sensory attributes
PGRC/E #69349 1hr 48 hr 24 hr Effects of storage time on maximum force required to bend injera from sorghum (PGRC/E #69349)
SK82-022 Tef 3443-2op 76TI #23 Effects of cultivars on maximum force required to bend injera AW after 48 hrs of storage Tef injera had a higher score of 8.2 for softness in a sensory evaluation
Parameter Maximum force required to bend injera (texture analysis) (after 24 hr of storage) (after 48 hr of storage) Significant correlations vs vs Sensory textural attributes and correlation coefficients Rollability 0.47* Softness 0.51*, rollability 0.52*, grittiness 0.54** Hardness (TADD) vs Softness 0.70***, rollability 0.66*** Endosperm texture (visual rating) vs Softness 0.59** Vitreousness (image analysis) vs Softness 0.59** Test weight (hectoliter weight) vs Softness 0.61**, rollability 0.54**
Parameter RVA parameters Significant correlations (continues) Peak viscosity (flour) vs Stickiness 0.46* Final viscosity (flour) vs Shininess 0.48* Setback viscosity (flour) vs Shininess 0.50* Hot-paste viscosity (flour) vs Stickiness 0.50* Water solubility index (flour) vs Fluffiness 0.48* Sensory textural attributes and correlation coefficients Water absorption index (flour) vs Stickiness 0.45*, fluffiness 0.70***
Conclusion Cultivars with floury endosperm, relatively lower test weight with low extraction rate were positively correlated with soft and rollable sorghum injera texture Water solubility index of the flour was positively correlated with fluffiness of injera These parameters have potential to be used as indirect indices in predicting the quality of sorghum injera in ESIP
Proposed selection criteria at early generation stage Parameter/method Acceptable ranges Remarks Pigmented testa (Chlorox Bleach Test) Absent These methods require Pericarp color (visual rating) Endosperm texture (visual rating) 3-5 White preferred Water solubility index (whole flour) 2.5 g/100 g Water absorption index (whole flour) 1.5 g/g small sample size and are predictive tests for injera making potential
Proposed selection criteria at advanced generation stage Parameter/method Acceptable ranges Hardness (TADD) (extraction rate) 56.0-79.0% Test weight (hectolitre weight) 71.0-75.0 kg/hl Sensory textural attributes of fresh injera Softness Score of 6.7 Stickiness Score of 2.0 Fluffiness Score of 6.8 Roll ability Score of 7.2 Remarks The sample size from advanced lines is large enough to prepare the actual product
Proposed selection criteria at advanced generation stage Parameter/method Grittiness Maximum force required to bend injera (texture analysis) (after 24 hr of storage) (after 48 hr of storage) Acceptable ranges Remarks Score of 2.7 The sample size from advanced lines is large enough to prepare the 0.27 N actual product 0.33 N
Future research needs It is required to test a larger number of sorghum lines, about 15-20 cultivars across 2-3 locations Test exclusively soft and hard endosperm sorghum cultivars to more clearly understand the effect of grain endosperm texture In-depth study on the structural properties of starch components of the cultivars with high and low staling properties is required
Acknowledgements The South African National Research Foundation for sponsoring me to attend this conference The organizing committee for inviting me to present my work