Unlocking Grain Nutrition Through Technology

ESPOO, FinlandIts commonly known that whole grains are more nutritious than milled grains, mainly because of the nutrients contained in grains branthe portion removed in the milling process. But scientists in the HEALTHGRAIN project of the European Union have found ways to create new healthy ingredients by innovative milling techniques and processes for cereal grains.

The bioaccessability of many of the healthful compounds, such as fiber, micronutrients and phytochemicals, that are concentrated in the bran layers of cereal grains is low because they are trapped in strong cell wall structures which resist conventional milling. Often they are concentrated near contaminants such as microbes, mycotoxins, pesticide residues, heavy metals. Scientists are developing new milling technologies, including partial grain debranning, fine grinding and classification of grain fractions, to manufacture flours with high levels of selected parts of the outer layers.

One technique examined was removing the grains outermost layers by partial debranning by combining peeling or pearling with milling (grinding and sieving). This creates flours with specific composition and controlled bioactive content, as monitored by the marker methodology. These have a better nutritional content than regularly milled flours, while ensuring product safety.

Researchers have also identified biochemical markers in the different portions of the grain (pericarp, intermediate layers, aleurone layers, germ) to determine the composition of the fractions after fractionation operations. This involves more-rapid methods for fractionation monitoring and new devices coupled with microscopy and microspectroscopy to help the development of fractionation with improved resolution. The scientists are looking at the effects of temperature, water content and enzymatic pretreatments of the grain in terms of the composition.

Another way to create healthier grain ingredients is to use millers bran, a byproduct of the milling industry, as a source of healthy ingredients. Careful limited grinding and sieving of the bran allowed concentration of aleurone cells and aleurone layer, source of most of the bioactive compounds of the grain. Further purification by electrostatic classification resulted in practically pure aleurone cells with excellent nutritional properties.

Ultrafine grinding of bran in ambient or cryogenic conditions resulted in an increase in bioactive compounds bioaccessibility. Classification using a electrostatic separator created fractions of very different compositions from the starting bran. One ingredient, with concentrated fine aleurone particles, showed a good accessibility of antioxidants and minerals compared to bran and untreated aleurone.

The work was conducted by INRA, in close collaboration with different partners in charge of analyses (VTT, KU Leuven, University of Helsinki, University of Uppsala, Puratos, TNO), development of analytical equipment (Branscan), and industrial demonstration and cost evaluation (Barilla, Buhler, SD-Tech).