Effects of high and low molecular weight glutenin subunits on rheological dough properties and breadmaking quality of wheat

High molecular weight (HMW) or low molecular weight (LMW) subunits of diffe rent chemical state (reduced, reoxidized with KBrO3, or KIO3) or gliadins w ere added in 1% amounts to a base flour of the wheat cultivar Rektor and mi xed with water. The corresponding doughs were then characterized by microsc ale extension tests and by microbaking tests and were compared to doughs fr om the base flour without additives. The maximum resistance of dough was st rongly increased by HMW subunits in a reduced state and by HMW subunits reo xidized with KBrO3. A moderate increase of resistance was caused by HMW sub units reoxidized with KIO3 and by LMW subunits reoxidized with KBrO3 or KIO 3. This resistance was strongly lowered by LMW subunits in a reduced state and by gliadins. The extensibility of dough was significantly increased onl y by gliadins and reduced HMW subunits; HMW subunits reoxidized with KBrO3 had no effect, and all other fractions had a decreasing effect. In particul ar, glutenin subunits reoxidized with KIO3 induced marked decrease of exten sibility, resulting in bell-shaped curve extensigrams, which are typical fo r plastic properties. The effect of reoxidized mixtures (2:1) of HMW and LM W subunits on maximum resistance depended on the oxidizing agent and on the conditions (reoxidation separated or together); extensibility was generall y decreased. Bread volume was increased by addition of HMW subunits (reduce d or reoxidized with KBrO3) and decreased by LMW subunits (reoxidized with KBrO3 or KIO3) and by a HMW-LMW subunit mixture (reoxidized with KBrO3). Th e volume was strongly decreased by addition of reduced LMW subunits. A high bread volume was related to higher values for both resistance and extensib ility.