Journal of Food Processing & Technology

Abstract

Optimization of Formulation and Process Conditions of Gluten-Free Bread from Sorghum using Response Surface Methodology

Shimelis Admassu Emire and Dawit Demelash Tiruneh

Grain and flour characterizations of two improved sorghum varieties (Gambella-1107 and 76T1#23) grown in Ethiopia was conducted from the perspective of their incorporation into Gluten-Free Bread (GFB). The sample varieties were evaluated for physicochemical and functional properties and their antinutrient compositions. In addition, GFB was produced from sorghum flour (50% flour weight basis), corn flour (20%), potato flour (10%) and chick pea flour (20%). Response Surface Methodology (RSM) was used to optimize the formulation and process conditions. The independent variables (factors) for the experiment were egg albumin level, milk powder level, baking temperature and time. The investigated responses were volume expansion, moisture loss, loaf height and bread hardness. Overall optimization, conducted by overlaying the 3-D plots under investigation, was able to identify an optimal range of the independent variables within which the four responses were simultaneously optimized. The point chosen as representative of this optimal area corresponded to egg albumin (2.5% flour-weight basis), milk powder (7.5%), temperature (220°C) and baking time (35 min), process conditions under which the model predicted volume expansion (597 cm3), moisture loss (4.02%), loaf height (3.43 cm) and bread hardness (3.88 N/g). The optimum GFB contain 78.9% dry matter, 12.3% crude protein, 3.9% crude fat, 2.4% crude fiber, 1.7% total ash and 58.6% total carbohydrates. Sensory evaluation indicated that the overall acceptability of the optimum GFB was much more similar to commercial GFB produced by local bakeries than the existing formulated GFB. Hence, the optimum formulation and process conditions can be used as starting point for bakers to produce GFB and to contribute to the eradication of the celiac problems in Ethiopia.