Quality evaluation of the porous crumb structure of leavened baked goods, especially bread, has become a vast study area of which various research studies have been carried out up to date. Here is a brief review focusing on those studies with six main parts including porous crumb structure development, crumb cellular structure analysis, application of fractal dimension for evaluating crumb cellular structure, mechanical and sensorial properties of crumb structure, changes of porous crumb structure with staling, and modifications to obtain a well-developed porous crumb structure and retard staling. Development of the porous crumb structure mainly depends on dough ingredients and processing conditions. Hence, certain modifications for those factors (incorporating food hydrocolloids, emulsifiers, improvers, etc.) have been conducted by cereal sciences for obtaining well-developed porous crumb structure and retard staling. Several image analysis methods are available for analyzing microstructural features of porous crumb structure, which can directly affect the mechanical and sensorial properties of the final product. A product with a well-developed porous crumb structure may contain the property of higher gas retention capacity which results in a product with increased volume and reduced crumb hardness with appealing sensorial properties.

Porous crumb structure of rice‐related leavened food products developed under air pressure conditions during fermentation and gelatinization in a fabricated fermentation chamber were characterized. Therein, four samples were prepared under three pressurized conditions (sample pressurized by the leavened gas itself, 1 kg/cm2 initial pressure, 1.5 kg/cm2 initial pressure) along with a control (unpressurized). Crumb volume, specific volume, bulk density, pH as well as crumb texture profile and cellular structure were analyzed. Results revealed that fermentation and gelatinization under air pressure (slightly higher than the atmospheric air pressure) conditions in the fabricated fermentation chamber help to arrest leavening gas within the dough mass to improve the properties of porous crumb structure. Sample fermented and gelatinized at 1 kg/cm2 initial pressure presented better crumb mechanical and cellular structural properties compared to the other two pressurized samples and the control.

Research background. Various processing techniques impart significant impacts on physicochemical and functional properties of rice flour and the quality of the final products. This study aims to modify rice flour from different treatment combinations and to select the best treatment combination in developing rice-wheat-based leavened food products. Experimental approach. Eight treatment combinations were applied on rice flour according to 23 factorial design considering three variables at two levels namely, pre-treatment for rice grain modification [heat-moisture treatment, dual modification treatment (soaking rice grains in a NaHCO3 solution followed by heat treatment)], grinding technique (dry grinding, wet grinding), and flour particle size (75-180 µm, <75 µm). Eight dough samples were prepared by mixing 50 g of rice flour from each treatment with 50 g wheat flour. Thereafter, the dough samples were subjected to fermentation and gelatinization under pressurized condition (externally applied 1.0 kg/cm2 initial air pressure condition) in a pressure adjustable chamber. Results and conclusions. Results rendered that rice flour sample that underwent heat-moisture treatment followed by wet grinding and particle size at 75-180 µm, impart to improve the leavened gas retention capacity and obtaining highly porous and better textured rice-wheat based leavened food products under 1.0 kg/cm2 externally applied initial air pressure condition. Novelty and scientific contribution. Rice flour can be modified according to the present method to improve functional flour properties and the textural and structural properties of rice-wheat based leavened food products. Also, conducting fermentation and gelatinization under pressurized condition is a novel food processing technique, which contributes in restricting the escape of leavened gas from rice-wheat composite dough mass.

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Well-porous structured leavened food products with a proper texture have a high demand in the dynamic food market. Hence, the current study was focused to formulate a leavened food product with a proper porous and better-textured crumb using rice-based composite flour (CF). Nine CF samples were prepared according to Taguchi’s orthogonal array by taking three variables (corn flour, finger millet flour, green gram flour) at three levels (0, 5%, 10%). Nine dough samples were prepared from each CF sample and subjected to fermentation and gelatinization under 1 kg/cm2 initial air pressure condition. Results revealed that crumb sample prepared from CF4 (Rice: Wheat: Corn: Green gram, 50:40:5:5) showed higher crumb volume, specific volume, lower bulk density and better crumb cellular structure properties which did not significantly different (p>0.05) to CF1 (Rice: Wheat, 50:50). Further, CF4 imparted to have the lowest crumb hardness, gumminess and chewiness. Thus, CF4 was selected as the best CF sample, which yielded a leavened food product with better textural and structural properties. Keywords: composite flour, fermentation, porous-crumb structure, rice flour, Taguchi’s orthogonal array