Development of a Gluten-free Bread with a High-protein Rice Flour and Effects of Alpha-amylase Enzyme Addition

Gluten-induced conditions such as celiac disease, wheat allergy, and non-celiac gluten sensitivity (NCGS) require the removal of common bakery products, including bread and cookies, and also pasta. The food industry has been developing gluten-free foodstuffs (GFF); however, these have been shown to contain low protein, fiber, and micronutrient levels, while being high in fat content and glycemic index. Bread is a staple food and is the most studied and consumed of GFF. Throughout this study, the flour obtained from a high-protein rice cultivar called Frontière was used for the elaboration of GF breads with the addition of alpha-amylase enzyme to replace starch. Proximate analysis, physico-chemical properties and consumer acceptance were evaluated. Four formulations of bread (T1: white rice flour, T2: white rice flour with α-amylase enzyme, T3: brown rice flour, T4: brown rice flour with α-amylase enzyme) were developed. For the physicochemical analysis, baking loss, specific volume, texture, and color were evaluated. In addition, a sensory analysis was performed. The data were statistically analyzed by ANOVA and LS-means (P < 0.05). Both formulations with α-amylase enzyme (T2 and T4) presented significant (P < 0.05) higher baking loss values (%) than T1 and T3 independently from the type of flour used. Also, formulations T2 and T4 displayed greater specific volume values of the breads (5.78 ± 0.02 cm3/g and 5.73 ± 0.04 cm3/g, respectively) compared to the breads without enzyme. Crust and crumb color reported significant differences (P < 0.05) for L*, a*, and b* values. However, those differences were not associated with α-amylase enzyme addition, but with the type of flour used. For texture, significant lower values (P < 0.05) were found in hardness, chewiness, and cohesiveness for the α-amylase treated breads (T2 and T4). Sensory characteristics were also positively influenced (P < 0.05) by α-amylase addition and purchase intent before and after health claim. The study demonstrated that the addition of α-amylase enzyme in combination with either white or brown high-protein rice flour can improve specific volume values, significantly enhance texture parameters (hardness, chewiness, and cohesiveness), and sensorial properties which are desired attributes in GF breads.