Caractérisation des facteurs influençant la structure de l’amidon et ses conséquences sur la valorisation du froment indigène

Characterization of the factors influencing the strach structure and this consequences on the indigenous wheat valorization

Context

During last decades, the agronomic evolution of the wheat culture in our areas was important. It, comes, moreover, of the progress made in the optimization the intrants, in particular of the effectiveness of plant health protections and the application of suitable nitrogen fertilization, but also of the improvement of the ears fertility and the average weight which allowed a strong progression of the yield (more than 3000 kg/ha in Belgium during 20 last years). It results from this progress that the conditions of filling and maturation of the grains strongly changed and can have involved important modifications on the composition of the major components of the grain and more particularly of the starch structure. In parallel, the appreciation of the quality of the batches of wheat within the various transformation chains seems to bring more and more problems, particularly within the flour-milling-bakery network. Indeed, recently, it was shown that the relation "Hagberg Falling Number (FN)-amylase activity" was not always respected, and that the measurement of the FN, based on the reduction of the starch paste viscosity of the flours under the action of the enzymes, could also cover with the aspects related to the starch composition and structure. These various observations bring to the need for studying more in-depth the starch of the grain as well as the relations existing between its technological qualities and the phytotechny applied to the culture, following the example protein fraction of the grain, already largely studied.

Objectives

The project is integrated in a framework of a better valorization of indigenous wheat into the three main transformation chains (flour-milling-bakery, starch industry and animal feeds) by the means of a better understanding of the starch properties. The major objective consists in the characterization of the factors linked to the genetic, the phytotechny (quantity and fractionation of the nitrogen fertilization, protections fungicidal, dates of sowings...) and the environment which are likely to influence, on the one hand, the structure of the starch (granules size, amylose content, pasting properties, degree of polymerization of amylopectin...) of wheat and, on the other hand, the enzymatic activities (amylasic) present in the grain which can degrade this starch. The long term objectives of the project provide are to provide to the various actors of the transformation chains precise farming routes with an aim of producing starches of differentiated quality.

Results obtained

The research undertaken during the first convention showed significant differences between the characteristics of the starches (granules size, amylose content, starch damage, thermal properties) resulting from varieties selected and cultivated according to various farming methods. These unsuspected differences observed on the intrinsic characteristics of starch and consequently its functional properties; allow a differentiated use for indigenous wheat lots and consequently a better valorization of these lots. Like the potato transformation chain, the varieties and cultivation methods should be chosen according to the industrial final applications. The study of the enzymatic aspects revealed that it is very difficult to separate the properties the starch itself from the hydrolytic action of alpha-amylases. This is why the wheat lots should be directed according to the intrinsic characteristics of the starch but also according to their inseparable amylolytic activities.

Partners

This project is the result of a collaboration between the FUSAGx (Unité de Technologie des Industries agro-alimentaires and Unité de Phytotechnie des Régions tempérées) and the CRA-W (Department Valorisation of agricultural products.