Exploring the relationships between food processing and nutritional properties of wheat and sorghum-based products

The aim of this thesis is to investigate some key nutritional and compositional characteristics of wheat and sorghum, with the purpose of exploring the interplay between the food technologies behind the processing of these cereals and their potential impact on human health. Specifically, in this work we investigated: A) the effect of stone milling and roller milling on a single lot of soft wheat on the hygienic quality, technological characteristics and antinutritional, proinflammatory properties of whole grain flour, dough rheology and bread quality; B) the synergistic effect of processing technologies (fermentation and germination) on the nutrient density, physical properties, and digestibility of sorghum porridge. This thesis is organized in 6 chapters and analyses the correlation between food processing and the nutritional characteristics of cereal-based products. Chapter 1 presents a general introduction on wheat and sorghum, then focusing on two products obtained from such cereals, namely bread and porridge, respectively. It also reviews wheat-related disorders and the problem of malnutrition in Sub-Saharan Africa, thus emphasizing the importance of food technology. Chapter 2 and chapter 3 evaluate the effect of stone milling and roller milling of soft wheat, since they generate different temperatures and apply peculiar frictional and compressive forces that could affect the composition of proteins and starch. These changes in composition in turn influence the properties of the flour, dough, and bread. Chapter 2 focuses on the hygienic (mycotoxins and alkylresorcinols content) and technological characteristics of wholegrain flour, dough rheology (farinograph and alveograph parameters) and on the quality (specific volume, moisture content and crumb texture) of bread made with flours obtained from RM e SM. Chapter 3, on the other hand, examines the proinflammatory properties of flour proteins on cell cultures, as SM and RM could differently affect amylase/trypsin inhibitors' extractability, redox state and play a role in the onset/exacerbation of non-coeliac wheat sensitivity. Chapter 4 and chapter 5 analyse the synergistic effect of processing technologies (fermentation and germination) on the nutrient density, physical properties and digestibility of sorghum porridge intended for weaning food. Chapter 4 analyses the effect of fermentation and germination on the nutrient density, physical properties, viscosity, and in vitro starch/protein digestibility of sorghum porridge by comparing the following formulations: I) sorghum porridge; II) fermented sorghum porridge; III) fermented sorghum porridge fortified with ungerminated pumpkin seeds; IV) fermented sorghum porridge fortified with germinated pumpkin seeds. Chapter 5 analysed the effect of fermentation on the nutrient density, physical properties, viscosity, and in vitro starch/protein digestibility of sorghum porridge by comparing the following formulations: I) sorghum porridge; II) fermented sorghum porridge; III) sorghum porridge fortified with baobab fruit pulp; IV) sorghum porridge co-fermented with baobab fruit pulp; V) fermented sorghum porridge and fortified with baobab fruit pulp added after cooking. Chapter 6 presents the general conclusion of the whole thesis work, summarizing the main results obtained and discussing future perspectives.