Grain Fractionation to Improve the Nutritional Intensity of Cereal Products

International audienceCereal products are generally produced using purified flours extracted from the wheat grain endosperm by themilling industry. However, whole grains contains appreciable concentrations of micronutrients, phytochemicalsand fibres that are mostly eliminated with the bran. These nutritionally interesting compounds are distributedwithin the peripheral layers of the grain (i.e. pericarp, testa and aleurone layer as the major tissues) whichshow distinct structure and mechanical properties. New dry fractionation processes were investigated in orderto recover these compounds while keeping a matrix effect (in contrast with wet extraction processes). Startingmaterial was either whole grain to partially incorporate the peripheral tissues into ”enriched” flours or milledbran to produce specific ”functional” cereal-based ingredients. A multi-scale approach, from grain batchesto specific molecules, was used to find out the key factors which govern the grain fractionation and theirgenetic variability and further develop the new processes. Grains were dissected into their main constitutivetissues which were individually characterised in terms of composition, structure, mechanical properties andmicro-milling behaviour. This approach allowed to determine the involvement of each of the main peripheraltissue in the bran rigidity, elasticity and extensibility and gave informations on the way to dissociate them.Biochemical markers were also identified and could be used to track each of the different tissues in the differentmilling fractions produced from complex processes. On the basis of the knowledge acquired from modelstudies, combinations of conventional (milling, grinding, sieving) and advanced technologies (pre-treatments,debranning, abrasion, attrition, jet-milling, air-classification) demonstrated the possibility to produce flourscontaining selected peripheral compounds or to prepare different fractions of contrasted composition frombrans