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Investigation of the Effect of Hot Air Drying of Wheat Gluten on Its Viscoelasticity and Baking Performance by a Systems Analytical Model

¹Technical University Berlin, Institute of Food Technology, Seestrasse 11, D-13353 Berlin, Germany. ²Corresponding author. E-mail: meus1533@mailszrz.zrz.tu-berlin.de. ³German Research Institute of Food Chemistry and Kurt-Hess-Institute of Flour and Protein Research, Lichtenbergstrasse 4, D-85748 Garching, Germany.

Drying experiments were conducted with wet gluten according to a newly developed systems analytical model to describe the effect of drying parameters on the viscoelasticity of wheat gluten and its baking performance. Gluten was extracted from two wheat flours differing in protein, wet gluten content, and viscoelastic properties as determined by extensigrams and farinograms. The glutens extracted from doughs were mixed with wheat starch (A grade) to establish a model system in which the most important drying parameters (hot air temperature, dry matter content of the feed, add-back cycle) could be varied on different levels. The gluten-starch mixtures were dried by a flash dryer. The experiments were designed according to a factorial experimental plan in which the drying parameters were correlated with the shear time of the glutens extracted from the dried products. Aliquots of the extracted glutens were freeze-dried and used for dough-forming experiments (microfarinograms) and microbaking tests. The dough development time and the baking volume were each statistically related to the shear time. Viscoelasticity of the glutens originating from the two flours decreased with increasing hot air temperature and number of drying steps. Lowering the dry matter content of the feed resulted in a similar reduction. The declining viscoelasticity was reflected in increased dough development time and decreased baking volume. Thus, the functional relationships postulated by the systems analytical model developed for the description of the gluten drying process have been verified on the basis of the statistically evaluated results of the drying experiments. From this follows that the viscoelasticity of gluten can be controlled by varying the parameters of hot air drying processes.