Assessing Influence of Protein Source on Characteristics of Gluten-Free Breads Optimising their Hydration Level

Most gluten-free products have lower protein content than their counterparts with wheat flour. The addition of exogenous proteins could not only be a good option to compensate for this reduction but also a tool to create gluten-free products rich in protein. However, the different water-binding capacities of proteins modify dough rheology, which also affects bread volume. Therefore, this study aimed to analyse the incorporation of a high percentage (30%) of several proteins (rice, pea, egg white and whey protein) in gluten-free breads whose hydration levels were adjusted for each protein to achieve the maximum volume. In this way, the breads with vegetal proteins required a higher amount of water than the breads with animal proteins. Moreover, all enriched breads exhibited lower maximum volume values than control, and the ones with whey protein presented the lowest volumes overall. From these results, the rheological behaviour and characteristics (colour, texture and weight loss) of optimised doughs and breads were measured. The doughs with whey protein presented the highest G′ and G″ values due to their low hydration level, and the ones with egg white protein were very watery. Regarding colour, the addition of protein led to darker crusts, with the ones with whey protein being the darkest. With respect to the control, breads with animal proteins exhibited higher hardness, especially with whey protein, while the ones with vegetal proteins did not present significant differences.