The bioactive compounds of cereals are concentrated in the peripheral layers of the grains (bran) but most of them have a low bio-accessibility. In the HEALTHGRAIN project of the European Union, new tools for process monitoring were developed that support commercial implementation of innovative milling techniques including partial grain debranning, fine grinding and classification of grain fractions, resulting in flours and ingredients with enhanced nutritional properties.
The wheat grain is a heterogeneous structure with bio-active compounds unevenly distributed within its different parts. The bioactive compounds (fibres, micronutrients and phytochemicals) are mostly concentrated in the grain outer layers, each having its own compositional profile. Therefore levels of bioactive compounds in whole meal flour are at least two times higher than those in white flour. However, some of the bioactive compounds have a low bio-accessibility in peripheral layers as they are trapped in strong cell wall structures which resist conventional milling. They can also be localized close to undesirable contaminants such as microbes, mycotoxins, pesticide residues, heavy metals. Therefore novel technologies have been developed for the transformation of the grains to better exploit their nutritional potential and to ensure food safety requirements.
In order to develop new dry processing techniques, new tools based on new insights in grain tissue composition, structure and properties have been obtained. Biochemical markers of the different grain tissues (pericarp, intermediate layers, aleurone layers, germ) have been identified and allow to determine the tissue composition of the technological fractions and deduce the behaviour of the different grain parts upon fractionation operations. More rapid methods for fractionation monitoring using spectral signature of tissues are on the way. New mechanical devices coupled with microscopy and microspectroscopy have been
|Contact: Xavier Rouau|
VTT Technical Research Centre of Finland