Summary The aim of this study was to propose a treatment to reduce the content of total polyphenols (TPP) and to obtain flour without significant morphological changes in the starch granules. The response surface methodology (RSM) was used to predict the influence of temperature and time on TPP extraction. Research work was conducted using the central composite design methodology. Results showed that the effect of temperature was more significant than that of time. A quadratic fit of data regarding temperature and linear data adjustment as to time was obtained. A scanning electron microscopy analysis of starch showed no morphological change in the granules at the temperature studied. Starch granules presented a size distribution ranging from 6 to 25 μm being 35% of granules <15 μm, and 65% of granules >15 μm in size, respectively.

The present work evaluates the potential of sorghum with high content of tannins for wholegrain flour production. Two types of mills were used: a roller mill (RM) and a blade (BM) mill. The impact of moisture and grinding on yield, physical, chemical and thermal properties were evaluated. Maximum yield was obtained using a BM with 25% moisture in the grain, resulting in 60.9% versus 28% (g flour/g of wholegrain sorghum) for the RM. Grain moisture and milling type affected flour colour and ashes. For both mills, the pasting and thermal properties of flour with grain moisture variation were significantly different from the untreated control sample. By studying the procedures for flour production and quality characteristics, it is possible to produce flour with good physical attributes, which can contribute to the development of gluten-free foods based on sorghum for the celiac population.

Summary Beer is an alcoholic beverage made with barley as a basic raw material, and therefore, it is not suitable for people with coeliac disease. During the brewing process, the elimination of the haze‐active precursor is performed at the stabilisation stage. Some breweries use silica gel (SG) as stabilisation precursor. This work presents the studies conducted to identify the stage where the addition of SG is more convenient in order to reduce gluten, and the effect on the yeast nutritional value due its incorporation. The incorporation of SG during fermentation allows the reduction in more gluten than the others brewery stages studied, without changing significantly the yeast nutritional value of beer. Furthermore, the use of SG promotes the reduction in polysaccharides which obstruct filtration.