AN APPROACH FOR POTENTIAL IMPROVEMENTS IN PROTEIN FUNCTIONALITY: DIFFERENT METHODS OF PROCESSING WHOLE-GRAIN SORGHUM

Sorghum (Sorghum bicolor (L.) Moench) represents the world's fifth most important cereal crop. As it is free of gluten-forming proteins, sorghum has excellent potential to be included in the diet of individuals with celiac disease or other gluten-related disorders. Food products to which this cereal is added have a high potential to be classified as promoting good health due to sorghum's bioactive compounds. As few processed foods and ingredients are made with sorghum, such products reach fewer people worldwide. However, sorghum consumption and its use in food formulation present some nutritional and technological challenges. Starch and protein are the main chemical components of all cereal grains. Both play essential roles in the nutritional quality of grains and affect utilization and end-use quality through their functionality. Unlike wheat proteins, sorghum proteins are not highly functional because they are encapsulated in protein bodies, making their participation in forming viscoelastic mass fibrils unavailable. Sorghum proteins are classified into prolamins (kafirins) and non-prolamins. In the whole grain, kafirins correspond to about 55% of the total proteins. Kafirin can potentially have some functionality as a viscoelastic material, as it has formed "viscoelastic masses" when coacervated in glacial acetic acid. However, processing could be critical to fully unlocking this possibility. Consumption of sorghum, specially pigmented grains, presents other challenges due to multiple anti-nutritional components that negatively affect feed efficiencies, such as condensed tannins, phytic acid, and trypsin inhibitor, which are responsible for inhibiting protein digestibility and bioavailability of minerals. The nutritional and technological bottlenecks of whole-grain sorghum can be minimized using various technological processing approaches. In this way, the processing of sorghum is considered a prerequisite for its use in the manufacture of improved food products since these technological processes can significantly affect the physical structure of the tissue, the nutrient content, and the functionality of the grains and, consequently, of sorghum products. In this context, advanced processing and value-adding technologies must be investigated to develop new sorghum-based food products with high consumer acceptance. The employment of four processes [dry milling (mechanical), thermoplastic extrusion (traditional thermal), high hydrostatic pressure (non-thermal), and fermentation (biological treatment)] could overcome the nutritional, technological, and sensory inconveniences of using whole-grain sorghum in food formulation. Different processing methods applied to sorghum flour can influence variably the performance of this cereal in gluten-free products to which they are added. A complete technological, physical-chemical, and biological characterization is necessary to decide which food product best suits the whole-grain sorghum flour from each of the suggested processes. However, few studies have emphasized the potential use of sorghum in industrial food formulations so that this cereal can be included in the diet as a healthy, sustainable, tasty, and convenient alternative with improved technological and nutritional characteristics.