Process Optimization And Quality Characterization Of Tef Flour For The Industrial Manufacturing Of Injera

Tef [Eragrostis tef (Zucc.)Trotter] is an Ethiopian indigenous tropical cereal crop and it has beenrncultivated for many years in Ethiopian highlands. Tef injera making in industry scale holds arnsignificant economic and social interest but requires a thorough study of how the processrnvariables affect the product quality. Tef is the main staple in the country mostly used to makerninjera. Injera is Ethiopian flat bread which is mostly made from tef flour. The general objectivesrnof this thesis was optimizing injera making process (milling, kneading and Absit or scolded doughrnpreparation) and identify the quality characteristics (tef flour and dough which includes flourrnfunctional and textural properties, dough rheological properties, injera sensorial quality andrnstarch digestibility of injera) of tef flour, dough and injera for industrial manufacturing by 1)rninvestigating the effects of mill type (hammer, disc, and blade), kneading conditions and injerarnabsit preparation on injera sensorial quality; 2) assessing the effect of mill type and kneadingrnconditions on starch digestibility, tef dough fermentation kinetics and phytate to mineral molarrnratio;3) studying tef flour characteristics and its dough rheological properties as affected by millrntype; and 4) introducing software based inhere quality evaluation technique. Standard methodsrnwere adopted for all analysis and determinations. Injera made with disc mill flour had higherrnoverall sensorial acceptability (6.6) than that obtained from hammer mill (4.2) and blade millrn(4.1) flours. The injera made with blade mill flour obtained the lowest rapidly available glucosern(52.6) and rapidly digestible starch (47.3). Based on its higher injera overall acceptability andrnmoderate starch digestibility, DM flour was preferred.rnTef flour from blade mill had contained higher BD (0.77 g/mL) and FC (12.67 mL). On the otherrnhand, flours from disk mill had higher WSI (7.94 g/100g) while lower was for hammer mill (4.17rng/100g). A lower value (64%) of dispersibility was recorded on flour from disk mill. The highest hardness (2.09 N) and gumminess (0.75N) was recorded tef gels from blade mill. Tef flourrnprepared from hammer mill showed significantly lower values of G’1 and G”2 and higher valuesrnof Tan δ than other mill type flours. Tef flours from disk mill had significantly higher peak andrnbreakdown viscosity but lower trough viscosity values. Tef dough stickiness and forwardrnextrusion was significantly (p

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