286 Effect of hot air drying of wheat gluten on its stretching properties.

F. Meuser (1), A. Kutschbach (1), R. Kieffer (2), and H. Wieser (2). (1) Technical University of Berlin, Institute of Food Technology, 13353 Berlin, Germany; (2) Kurt-Hess-Institut für Mehl- und Eiweißforschung, 85748 Garching, Germany.

Model experiments were carried out to determine the effect of drying parameters on the stretching properties of wheat gluten. The wheat gluten was extracted from two wheat flours differing in wet gluten content. The gluten was mixed with wheat starch (A-grade) in order 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 in a flash drier (Ultra-Rotor). The experiments were designed according to a factorial experimental plan. For this the drying parameters were correlated with the stretching properties (Glutograph time) of the glutens extracted from the dried products. Aliquots of the extracted glutens were freeze-dried and used for baking tests. The volume of the baked products (bread) was correlated to the Glutograph time. All data were statistically evaluated. It could be shown that the stretching properties of the glutens originating from the two flours decreased with increasing hot air temperature and the number of add back cycles, respectively. Lowering of the dry matter content of the feed resulted in a similar reduction. The declining stretching properties were mirrored in decreasing volumes of the breads.