Comparative Effects of Inulin, Psyllium Husk, and Carob Seed Germ Flour as Fiber-Enriching Ingredients on the Quality of Baromi-2 Rice Flour-Based Gluten-Free Bread

Abstract

A novel type of rice called Baromi-2 offers big advantages over wet-milled rice flour in cost, processing time, and environmental protection. This study assessed the impact of different dietary fibers on the quality characteristics and antioxidant activity of gluten-free bread made from Baromi-2 rice flour (BRF). Bread formulations were prepared using inulin, psyllium husk, and carob seed germ flour at substitution levels of 5% and 10% (w/w) based on Baromi-2 rice flour, labeled as I5/I10, P5/P10, and C5/C10, respectively. A control formulation without fiber addition was included for comparison. All breads were produced using the straight dough method, comprising kneading, resting, and proofing steps. Results showed that psyllium husk and carob seed germ flour significantly reduced bread volume, creating denser textures, while inulin led to a softer bread with greater baking loss, likely due to its higher gelatinization temperature. Structural analysis revealed that inulin-enriched bread (I5, I10) had more porous structures, enhancing mechanical strength, whereas psyllium and carob seed flour bread (P5, P10, C5, and C10) had compact structures associated with higher hardness and chewiness. Antioxidant activity increased with fiber concentration, peaking in the C10 formulation (63.33% and 45.12%). Principal Component Analysis (PCA) revealed strong associations between fiber types and quality traits, particularly specific volume and baking loss. Inulin proved most effective for improving texture, highlighting its potential for enhancing gluten-free bread quality. These findings emphasize the essential role of fiber type and concentration in influencing textural, structural, and antioxidant properties in gluten-free bread formulations.