Effect of Process Variables on Rice Flour Functional Properties, and Porous Structure of Rice and Wheat-Based Leavened Food Products

RESEARCH BACKGROUND: Various processing techniques significantly affect physicochemical and functional properties of rice flour and the quality of the final products. This study aims to modify rice flour with different treatments and to select the best one to develop rice and wheat-based leavened food products. EXPERIMENTAL APPROACH: Eight treatment combinations were applied on rice flour according to 2(3) factorial design considering three variables at two levels, namely, pretreatment of rice grain (heat-moisture treatment, dual modification treatment: soaking of rice grains in NaHCO(3) solution followed by heat treatment), grinding method (dry or wet grinding), and flour particle size (75−180 and <75 µm). Eight dough samples were prepared by mixing 50 g rice flour from each treatment with 50 g wheat flour. Then, the dough samples were subjected to fermentation and gelatinization under pressure (externally applied 1.0 kg/cm(2) initial air pressure) in a pressure adjustable chamber. RESULTS AND CONCLUSIONS: Rice flour sample with particle size of 75-180 µm that underwent heat-moisture treatment followed by wet grinding improved the gas retention capacity of the leavened dough. With the externally applied initial air pressure of 1.0 kg/cm(2), we obtained highly porous and better textured rice and wheat-based leavened food products. NOVELTY AND SCIENTIFIC CONTRIBUTION: Rice flour can be modified using the described method to improve its functional properties, and the textural and structural properties of rice and wheat-based leavened food products. Also, conducting fermentation and gelatinization under pressure is a novel food processing technique, which contributes to restricting the escape of gas from leavened rice/wheat composite dough mass.