Cereal Chem. 80(1): [52][53][54][55] Enzymes are good tool to modify wheat proteins by creating new bonds between the protein chains. In this study, the effect of the addition of glucose oxidase (GO) and transglutaminase (TG) on the wheat flour proteins is presented. The modification of wheat proteins was determined by analyzing the changes in gluten quality, alveograph parameters, and protein modifications. The amount of wet gluten increased with the addition of GO and TG, but the gluten quality was not improved in any case. Regarding the alveograph parameters, the effect of GO was readily evident obtaining wheat dough with higher tenacity and lower extensibility than the control, while TG led to doughs with lower tenacity and that were also less extensible. The protein modifications were characterized by free-zone capillary electrophoresis (FZCE). FZCE data indicated that TG polymerizes mainly glutenins and, of those, the high molecular weight glutenin subunits were the most affected. 2 Corresponding

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The effect of Aelia spp. and Eurygaster spp. wheat bugs on the protein fractions of different wheat cultivars has been studied by size‐exclusion high‐performance liquid chromatography (SE‐HPLC) and free‐zone capillary electrophoresis (FZCE). Those methods were used to quantify and characterize the extent of protein modification. A decrease in the amount of alcohol‐insoluble polymeric proteins along with an increase in the alcohol‐soluble polymeric proteins and gliadins were observed in damaged wheat. The high molecular weight (HMW) and low molecular weight (LMW) glutenin fractions were barely detected in the incubated damaged wheat from some cultivars, which indicated hydrolysis of those proteins by the bug proteinases. In damaged wheats, both incubated and unincubated, gliadin electrophoregrams revealed the presence of some new peaks with mobilities similar to the ω gliadins. The overall results suggest that the bug proteinases are potent enzymes that appear to be nonspecific because they hydrolyze all gluten proteins.

The extent of modi®cation of wheat amylase activities caused by Aelia and Eurygaster attack on wheat grain was determined in different Spanish cultivars subjected to varying degrees of attack. High variation in diastatic activity and a-amylase and b-amylase activities was found between cultivars, but no relationship could be established between these activities and bug damage within cultivars. Scanning electron micrographs of the cross-section of damaged kemels showed an empty cavity under the bite point. The surrounding cell walls and protein matrix were absent, but the starch granules were intact. Since wheat damaged by Aelia and Eurygaster does not have altered amylase activities, it appears that amylolytic enzymes are not involved in the alteration of bug-damaged wheat.

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