HEALTHGRAIN Consortium Develops Definition for Whole Grain

Such a definition could be used by industry, by EFSA and food inspection agencies and by organisations involved in nutritional guidelines and communication to consumers.

5 May 2010 --- Cereal grain kernels consist of three main parts: endosperm, bran and germ. In Europe and worldwide most cereal products, like white bread, are based on kernels or flour after removal of bran and germ, the two parts containing most of the dietary fibre and other bioactive components. In the past decade consumers have been rediscovering whole grain based products. As a result consumption of whole grain products is growing world wide and in Europe also in countries where whole grain products were hardly known.

In a number of countries short definitions of whole grain exist stating, i.e. "Whole grain products include the entire germ, endosperm and bran. Grains that have been subjected to processing such as milling are also included." Recently more comprehensive definitions have been developed in the USA, Canada, UK and Denmark. These definitions include items such as a positive list of the grains included and specifications of allowed processes.

The HEALTHGRAIN consortium of the European Union has felt the need for developing a European definition of whole grain with the following scope:
•  More comprehensive than current definitions in most EU countries
•  One definition for Europe – when possible equal to definitions outside Europe
•  Reflecting current industrial practices
•  Useful in the context of nutritional guidelines and nutrition claims.

Such a definition could be used by industry, by EFSA and food inspection agencies and by organisations involved in nutritional guidelines and communication to consumers. A committee with Nils-Georg Asp (Swedish Nutrition Foundation, Sweden), David Richardson (DPRNutrirtion, UK), Kaisa Poutanen (VTT and University of Eastern Finland) and Jan Willem van der Kamp (TNO, Netherlands) took care of guiding the discussions and formulating the definition.

Key statements in the definition are:
• Whole grains consist of intact, ground, cracked or flaked kernel after the removal of inedible parts such as the hull and husk. The principal anatomical components - the starchy endosperm, germ and bran - are present in the same relative proportions as they exist in the intact kernel.
• Temporary separation of whole grain constituents during processing for later recombination is acceptable.

The HEALTHGRAIN Forum will develop this definition further for covering labelling issues of products consisting completely or partially of whole grains.

The EU Integrated HEALTHGRAIN project has substantially strengthened the scientific basis for a new generation of cereal based products with enhanced health benefits. The project also has formed a network of research organizations, industries and organizations communicating to consumers that will continue as the HEALTHGRAIN Forum. It has been coordinated by Academy Professor Kaisa Poutanen from VTT Technical Research Centre of Finland. Results of the project are currently being presented in the HEALTHGRAIN Conference on May 5-7 in Lund, Sweden.

At the Conference new tools for process monitoring will also be presented. These tools 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 developed to determine the local properties of tissues and of their interfaces to help the development of fractionation with improved resolution. Especially, the effects of temperature, water content and enzymatic pre-treatments have been investigated.

A way to enrich cereal products with bioactive compounds is to manufacture flours with high levels of selected parts of the outer layers. To remove the very outermost layers, partial debranning of grains in using friction (peeling) or abrasion (pearling), was combined with milling (grinding and sieving) to produce flours with tailored tissue composition and thus controlled in content of bioactive compounds, as monitored by the marker methodology. Flours made from peeled grains, peeled and pearled grains and grains with removed outermost layer and crease parts exhibited high contents of bioactive compounds and improved nutritional effects as compared to common flours.

Another way of exploiting cereal potential is to use the miller's bran, a by-product of the milling industry, as a source of healthy ingredients. Careful limited grinding and sieving of the bran allowed to prepare a concentrate of aleurone cells and aleurone layer, where most of the bioactive compounds of the grain are located. Further purification by electrostatic classification yielded practically pure aleurone cells that exhibited excellent nutritional properties.

Another approach used ultrafine grinding of the bran in ambient or cryogenic conditions, to provoke a full dissociation of the material at a sub-cellular level. This resulted in an increase in bioactive compounds bioaccessibility. Classification of the fine particles in using a electrostatic separator made it possible to prepare fractions of very contrasted compositions in starting from bran. One of these ingredients, concentrated in fine aleurone particles, showed a good accessibility of anti-oxidants and mineral compared to bran and untreated aleurone. These technologies have been experimented at large-scale by industrial partners, to determine their feasibility and economics.

The work was conducted by INRA, in close collaboration with difent 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).