Hans-Dieter-Belitz-Institute for Cereal Grain Research

Chemical Analysis

In combination with baking tests and rheological measurements chemical and analytical methods provide a comprehensive description of the properties of a flour. Previous investigations have shown that the baking quality of wheat flour is determined by the presence or absence of specific gluten protein components on one side, and by their amount on the other side. Therefore, methods have been developed at HDBI to determine the type and the quantity of gluten protein components in flour. In one method a small quantity of flour (100 mg) is extracted sequentially with different solvents into fractions that are analysed qualitatively by reversed-phase high-performance liquid chromatography.

In a second method, which has been developed for poorly equiped laboratorys, the amounts of gluten protein components in the fractions are determined spectrophotometrically with specific dyes. A crucial point is that the method has to be calibrated by using the protein freactions under study. The results can be used for the differentiation of wheat cultivars or for the prediction of the baking performance of flours.

Persons suffering from coeliac disease have to stick to a life-long gluten-free diet. They have to consume so-called gluten-free foods, which have to be checked for their gluten content by suitable methods that are sufficiently selective and sensitive. For this puropse ELISA methods based on different antibodies are being used. In addition, methods based on HLPC with fluorescence detection and on liquid chromatography-mass spectrometry (LC-MS) are currently being developed at HDBI.

Chromatogram of the HPLC-separation of a glutenin extract
Chromatogram of the HPLC-separation of gluten protein components. ω: ω-gliadins; HMW/LMW: high-/low-molecular weight subunits of glutenin

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