Dry processes to develop wheat fractions and products with enhanced nutritional quality

Numerous epidemiological studies have investigated the potential health benefits of consuming more wholegrain foods. However, in Europe, most wheat-based food products are made with refined endosperm from which the germ and peripheral layers (bran) are excluded, although these tissues have considerable nutritional potential and contain most of the micronutrients, phytochemicals and fibre of the grain. Dry fractionation technologies allow these peripheral tissues to be separated and recovered to efficiently separate valuable from detrimental components (i.e. contaminants, antinutrient compounds, irritants), in order to develop nutritionally enhanced ingredients and products. The rational development of efficient processes requires the ability to monitor the fractionation and understand the fate of grain tissues, and to take into account the various properties of the different parts of the grain in order to design an appropriate fractionation protocol. This review provides an overview of the existing processes that can be used for the production of wheat products and fractions with enhanced nutritional interest. The grain composition and properties are briefly introduced with emphasis on nutritionally interesting compounds. Tissue markers and their application in process monitoring are presented, and the physical properties that influence the fractionation properties of grain tissues are developed. The main wheat dry fractionation processes are then reviewed, including pretreatments, degerming, debranning, and bran fractionation.