Formulation of gluten-free pocket-type flat breads : optimization of methylcellulose, gum arabic, and egg albumen levels by response surface morphology

Abstract

Response surface methodology was used to analyze the effects of methylcellulose, egg albumen, and gum arabic on the sensory properties of gluten-free pocket-type flat bread baked from formulas based on pregelatinized rice flour and pregelatinized corn starch with corn flour. A rotatable central-composite design consisting of three variables (methylcellulose, egg albumen, and gum arabic), in a five-level pattern (1.37, 2, 3, 4, and 4.63 g) with 20 runs (gluten-free formulations), was prepared over three blocks. This design was used to develop models for the different sensory responses. Responses were affected most by changes in methylcellulose and egg albumen levels, and to a lesser extent by gum arabic levels. Individual contour plots of the different responses were superimposed, and regions meeting the maximum number of bread sensory attributes were identified. When 3 g of gum arabic was included in the bake mix, gluten-free breads comparable to regular wheat bread in the frequency of cracks, separation of layers, rollability, tearing quality, hardness, adhesiveness, and cohesiveness were obtained at methylcellulose levels ≥2.10 g and ≤4.12 g, and at egg albumen levels ≥2.18 g and ≤4.10 g. Higher levels (4.63 g) of gum arabic resulted in more cohesive products. lower levels (1.37g) of gum arabic produced loaves that were less cohesive and inferior to wheat bread in rollability. All breads possessed a perceptible corn flavor, a light-yellow crumb with apparent waxy patches, and a faster staling rate than that of regular wheat bread