Infodoc : Sciences, Techniques et Culture

Celiac patients cannot tolerate gluten, the protein from wheat, rye and barley that gives to dough the viscoelastic properties required to develop bakery products of good quality. Its lack results in liquid batter rather than dough, yielding breads with a crumbling texture, pale colour and poor mouth-feel. Many studies have been carried out in the last years, testing potential ingredients and complex formulations with the aim of reproducing gluten functionality and developing gluten-free breads as similar as possible to wheat ones. In this thesis, unicellular protein, legume flours and cheese whey have been studied as potential protein sources to improve gluten-free bread characteristics. Preliminary trials were performed to develop basic gluten-free formulations and optimize the brea[...]

Celiac patients cannot tolerate gluten, the protein from wheat, rye and barley that gives to dough the viscoelastic properties required to develop bakery products of good quality. Its lack results in liquid batter rather than dough, yielding breads with a crumbling texture, pale colour and poor mouth-feel. Many studies have been carried out in the last years, testing potential ingredients and complex formulations with the aim of reproducing gluten functionality and developing gluten-free breads as similar as possible to wheat ones. In this thesis, unicellular protein, legume flours and cheese whey have been studied as potential protein sources to improve gluten-free bread characteristics. Preliminary trials were performed to develop basic gluten-free formulations and optimize the bread making process. In the first study, starch, starch-vegetable and flour based formulations were prepared, and unicellular protein was added to increase bread protein content. Inclusion of unicellular protein caused a decrease in bake loss, an increase in hardness and a darkening of crumb and crust color. In a second study, four formulations prepared with legume protein sources (chickpea flour, pea protein isolate, carob germ flour and soya flour) were compared, with the aim of substituting soya flour. Carob germ flour bread presented the lowest specific volume and the highest hardness. Chickpea bread exhibited the best baking characteristics and, in general, good sensory behaviour, although its taste decreased consumer preference. Both chickpea flour and pea protein isolate could be promising alternatives to soya flour, due to its high allergenicity. A third study was performed to evaluate the effect of water and/or soya substitution by fresh and ripened liquid cheese whey in gluten-free bread. Combination of ripened or fresh whey and soya flour increased batter visco-elasticity and decreased bread specific volume. Breads with water or ripened whey and without soya were the most preferred by consumers, probably due to the softest texture and colour. In summary, specific improvements in gluten-free bread baking and sensory characteristics have been achieved during this research on gluten-free protein sources. Finally, the last study included in this thesis demonstrates that NIRS methodology can predict accurately the concentration of gluten content in flours and batters. However, it should not be considered as a reliable method for determining gluten content contamination in gluten-free products.