Characteristics of gluten-free bread: quality improvement by the addition of starches/hydrocolloids and their combinations using a definitive screening design

To establish factors affecting the quality of gluten-free bread based on rice semolina supplemented with field bean semolina and improving its final quality, a new study with definitive screening design was conducted after an appropriate choice of six factors: agar–agar, water, two types of gums gum arabic and locust bean gum, and two types of starches tapioca starch and corn starch. We investigated the effect of the aforementioned parameters on specific volume, hardness, chewiness, and springiness of breads. The results showed that specific volume of gluten-free breads increased significantly (p < 0.05) with the addition of gum arabic, tapioca and corn starches, and water; addition of agar–agar, gum arabic, tapioca starch and water affected the hardness. With regard to chewiness, the results showed that gum arabic and water and also the interaction between them had a significant effect. Gum arabic, tapioca and corn starches, and water affected the springiness. In addition, we observed the interactions among the additives. For all the tested parameters, water and gum arabic had statistically significant (p < 0.0001) effect and affected all the properties of examined breads. These factors were retained for process characterization of optimized gluten-free bread. The final optimum formulation of rice/field bean contained 1.5% of gum arabic and 71.5% of water. The optimum gluten-free bread with gum arabic showed high volume, good textural, structural, and sensory qualities with high acceptability compared to the gluten-free control bread without any improver.