Effects of heat treatment on protein denaturation and starch gelatinisation in wheat flour

In the EU, chlorination of soft wheat flour has been replaced in recent years, to some extent, by heat treatment for baking of high ratio cakes. The heat treated flour has enabled recipes to be developed which generate products with longer shelf life, finer texture, moist crumb and sweeter taste. It is not fully understood how heat treatment improves the flour; however, it is known that during the heat treatment process, protein denaturation and partial gelatinisation of starch granules occur. Therefore, it is important to quantify these property variations as they have a marked affect on the quality characteristics of baked products. Heat treated flour was prepared by heating base flour in a laboratory fluidised bed dryer using a range of temperatures and times. The gluten was extracted from the flour and its quality was tested in an extensibility gluten rig attached to a texture analyser to obtain objective and comparative information on the extent of protein denaturation. Another portion of the flour was used to measure gelatinisation temperature and peak viscosity. The results indicated that heat treatment of flour decreases gluten extensibility showing that protein denaturation occurred. Also, partial gelatinisation of the starch granules took place. The effects improve the baking quality of the cake product such as texture, height and volume.