Evaluation of functional properties of physically treated sorghum flours and development of gluten-free sorghum bread

Recently, sorghum production and utilisation experienced a considerable increase in the food industry due to its outstanding nutritional and functional properties as a gluten-free material. Depending on the genotype, it is a good source of antioxidants and contains a high amount of slowly digestible and resistant starch. This study evaluated the effect of physical (heat) treatment on the functional and rheological properties (water and oil absorption capacities etc.) of commercial sorghum flour. Gluten-free bread were also developed with the use of sorghum as base material and the addition of other gluten-free ingredients and the utilisation of heat treatment. Bread quality and texture profile characteristics (hardness, springiness) were evaluated, and an organoleptic test was also performed. Heat treatment proved to be beneficial in improving some of the functional properties of sorghum flour: it increased water absorption capacity by 20% compared to the control flour. It also improved the development of dough and the texture profile of bread on the baking day but resulted in a rapid quality decrease during storage. Sorghum bread with 10 % fibre content received the highest score during sensory evaluation, and a higher fibre content combined with heat treatment caused a significant decrease in hardness values. In conclusion, physical treatment had a favourable effect on some of the functional properties of sorghum flour and bread, especially water absorption capacity and dough development, and according to the organoleptic evaluation results sorghum bread products can potentially compete with other gluten-free bakery products.