The Use of Response Surface Methodology to Optimise Malting Conditions of Tef (Eragrostis tef (Zucc.) Trotter) as a Raw Material for Gluten-free Foods and Beverages

Celiac disease is a condition, in which case the person’s body reacts to the prolamins of wheat, rye, barley, and oats. The only way to treat CD is a total lifelong avoidance of gluten consumption. In this study Tef (Eragrostis tef L.), which belongs to the family poaceae that is regarded as gluten free, was used as raw material. The objective of this study was to optimize the malting conditions to produce a gluten free malt of high quality for gluten free foods. Tef, with a thousand kernel weight of 0.3–0.4 g, needed special arrangements like small sieves etc. Tef has a remarkable agronomical advantage that the water requirement is probably the lowest of any major cereal.

Response surface methodology was used to investigate the influence of the three malting parameters, vegetation time, degree of steeping and temperature on the quality of tef malt. Each predictor variable was tested at three levels. Vegetation times were 4, 5 and 6 days, degrees of steeping were 46, 50 and 54 % and vegetation temperatures were 16, 20 and 24 °C.

Kilning temperatures of 65 °C were used. The used analyses were based on methods outlined in EBC or by MEBAK. The raw material was yielded 2006 in Utah, USA.

A range of malt quality parameters was determined including extract, apparent attenuation limit, gelatinisation temperature, á-amylase activity, â-amylase activity, limitdextrinase activity, Kolbachindex, alpha amino nitrogen, viscosity, and colour. The achieved values slightly deviate from the calculated ones. The obtained attributes were 52.1 % extract, 69.1 % AAL, 84 U/g á-amylase activity, and 187 U/g â-amylase activity, 1062 U/kg limit dextrinase activity, 5.9 EBC colour, 285 mg/100 g FAN and 2.782 mPa x s viscosity.

This publication shows clearly that on the one hand RSM is a prove method for testing the malting conditions of unknown cereals and on the other hand Eragrostis tef is a crop with a potential as a raw material for malting purposes.

BrewingScience - Monatsschrift für Brauwissenschaft, 61 (May/Juni 2008), pp. 94-104