Effects of transglutaminase and glucose oxidase on the properties of frozen dough: Water distribution, rheological properties, and microstructure

The effects of transglutaminase (TG) and glucose oxidase (GOX) on the water distribution, rheological properties, and microstructure of dough after freeze-thaw cycles were studied. The results showed that, when TG (1%, w/w) and GOX (0.006%, w/w) were added to the dough simultaneously, the syneresis rate of the dough after 8 freeze-thaw cycles reduced by 12.9%, and the extensibility and maximum resistance of the frozen dough increased by 9.6 mm and 14.7 g, respectively. Moreover, the G′ and G″ values of the frozen dough were significantly increased, and the hardness and freezable water content were reduced by 60.1% and 2.9%, respectively. The LF-NMR analysis showed that the tightly bound water content increased by 4.9%, and the semi-bound water content decreased by 4.0%. The number of free sulfhydryl groups in the dough treated with the two enzymes decreased by 16.3 μmol/g. Fourier IR revealed that the content of α-helix increased by 3.1%, β-sheet increased by 5.8%, and β-turn decreased by 4.8%. Scanning electron microscope images indicated that the gluten network of the two enzyme-treated dough remained uniform and dense after multiple freeze-thaw disruptions.