FORMULATION OF GLUTEN-FREE POCKET-TYPE FLAT BREADS - OPTIMIZATION OF METHYLCELLULOSE, GUM-ARABIC, AND EGG-ALBUMIN LEVELS BY RESPONSE-SURFACE METHODOLOGY

Response surface methodology was used to analyze the effects of methyl cellulose, egg albumen, and gum arabic on the sensory properties of gl uten-free pocket-type flat bread baked from formulas based on pregelat inized rice flour and pregelatinized corn starch with corn flour. A ro tatable central-composite design consisting of three variables (methyl cellulose, 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 pr epared over three blocks. This design was used to develop models for t he different sensory responses. Responses were affected most by change s in methylcellulose and egg albumen levels, and to a lesser extent by gum arabic levels. Individual contour plots of the different response s were superimposed, and regions meeting the maximum number of bread s ensory 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, tearin g quality, hardness, adhesiveness, and cohesiveness were obtained at m ethylcellulose levels greater than or equal to 2.10 g and less than or equal to 4.12 g, and at egg albumen levels greater than or equal to 2 .18 g and less than or equal to 4.10 g. Higher levels (4.63 g) of gum arabic resulted in more cohesive products. Lower levels (1.37g) of gum arabic produced leaves 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.