Modelling the effects of orange pomace using response surface design for gluten-free bread baking

The development of gluten-free bread creates many challenges; producing bread that will match the properties of its wheat counterpart can be difficult. Fruit by-products are know from literature to contain a high level of dietary fibre which could improve the bread properties and fibre contents of gluten-free bread. Therefore, a mathematical design was created; three variables were identified from preliminary tests (water (85-100% flour weight, OP 0-8% flour weight and proofing time 35-100 min) as being crucial in the development of acceptable bread. Results illustrated longer proofing times (p < 0.05) and lower orange pomace levels (OP) (p < 0.001) produced a bread with a greater specific volume. OP had the most significant (p < 0.0001) effect on hardness at 2 h and 24 h post-baking. The optimised formulation was calculated to contain 5.5% OP, 94.6% water and a proofing time of 49 min. Total fibre content of the control bread (2.1%) was successfully increased to 3.9% in the OP containing bread. Substituting gluten-free flours with orange pomace flour can help improve the total dietary intake of a coeliac while not negating on the quality properties of the bread.