SPROUTING AS A BIOTECHNOLOGICAL PROCESS TO IMPROVE THE FUNCTIONAL PROPERTIES OF CEREAL-BASED PRODUCTS

Although some studies showed that the use of flours from controlled sprouted grain can improve bread properties, the relationship between macromolecule functionality and bread features needs to be investigated, especially in the case of fiber-enriched products. In this context, the PhD project focused on the assessment of the sprouting effects on the functionality of the main macromolecules in grains (i.e., protein, starch, and fiber) and their impact on dough and bread-making properties. In the introduction chapter (Chapter 2), a literature review has been carried out, where the main effects of sprouting on the nutritional profile of grains and their health benefits were summarized. Moreover, the scaling-up of the sprouting process from domestic to industrial level, the importance of monitoring processing parameters were addressed. The first two sections (Section 4.1 and 4.2) of the Results and Discussion chapter assessed the effects of the sprouting process on technological/functionality of wholegrain flours from common wheat. In particular, wholegrain flours were obtained from single-stream milling (Section 4.1) and the recombination approach by including 20% bran to wheat flour (Section 4.2). Sprouting process caused a worsening in both gluten aggregation kinetics – suggesting a gluten weakening – and starch pasting and gelation properties. However, following the conditions obtained by the Farinograph test, it was possible to obtain a wholegrain bread with improved characteristics in terms of volume and crumb softness. Considering the positive effect of sprouting on the bread-making performance of common wheat, the process was carried out on durum wheat (Section 4.3), with the aim of improving its gluten functionality for the production of durum wheat bread. For this reason, the effects of enzymatic activities developed during sprouting on durum wheat kernel characteristics, starch and gluten behavior were investigated, as well as their relationship with the bread-making performance. Although the sprouting process caused a decrease in the gelatinization and retrogradation capacity of starch and gluten aggregation properties, bread with improved volume and crumb porosity was obtained. In particular, the best results were obtained using wheat sprouted up to 48 h. The last part of the project focused on the sprouting of quinoa (Section 4.4) and sorghum (Section 4.5), whose consumption has been constantly increasing, since they are considered environmentally sustainable crops with high nutritional value. However, from the technological standpoint, the suitability of quinoa and sorghum for achieving good bread-making performance in wheat-based formulation still needs deep investigation. As regards enriched-bread, the presence of sprouted grains at 20% replacement level showed higher specific volume and lower crumb softness compared to control. In addition, in the case of sorghum, sprouting improved the in vitro protein digestibility. In conclusion, this PhD project provides evidence of how protein and starch functionality is affected by both the type of grain used and sprouting duration. In addition, bread-making performance of wheat-based formulations can be enhanced by using sprouted grains or their main milling fractions (refined flour or bran), opening a new approach to the production of fiber- enriched baked goods.