The development of analog rice offers a promising strategy to enhance the nutritional value of staple foods in regions where rice is a major carbohydrate source. Because consumer acceptance depends strongly on texture, understanding how composite ingredients interact as a hydrocolloid matrix is essential for engineering analog rice with desirable physical and structural characteristics. This study examined how a composite system of sago starch, fermented kidney bean flour (FKBF), and modified cassava flour (Mocaf) contributes to textural formation and microstructural integrity. The objective was to determine how variations in the sago-to-FKBF ratio influence the functional properties of the hydrocolloid matrix, with Mocaf fixed at 20%.

Five formulations were prepared with sago-to-FKBF ratios of 30:50 (F1), 35:45 (F2), 40:40 (F3), 45:35 (F4), and 50:30 (F5). Texture Profile Analysis (TPA) quantified hardness, springiness, cohesiveness, gumminess, and chewiness in cooked analog rice. Scanning Electron Microscopy (SEM) characterized starch granule behavior and structural uniformity, enabling evaluation of structure–function relationships governing texture.

The sago–FKBF ratio was the principal factor influencing physical performance. Sago-rich formulations (F4 and F5) exhibited greater hardness, elasticity, and structural strength. F5 showed the highest hardness (355.90 ± 14.39 g) and strong springiness (3.63 mm), reflecting the gelling characteristics of amylopectin-rich sago starch, which forms a cohesive and elastic matrix during gelatinization. The compact network created by sago enhanced mechanical stability and mouthfeel. In contrast, higher FKBF content disrupted starch network formation. SEM revealed porous, discontinuous structures with cavities and weak granule fusion. Proteins and fibers in FKBF likely competed with starch for water, limiting swelling and reducing gel strength.

This study demonstrates that the physical properties of analog rice can be predictably tuned by adjusting the hydrocolloid composition of the flour blend. A sago-dominant system promotes formation of a robust gelatinized network essential for achieving rice-like texture, whereas excessive FKBF weakens structural integrity. These findings provide a practical framework for improving analog rice and highlight the importance of starch-rich components for creating fortified staple foods that meet consumer expectations.