No abstract

No abstract

Present work seeks to systematically analyse the individual and synergistic effects of some gluten-crosslinking enzymes (transglutaminase, glucose oxidase and laccase), along with polysaccharide and gluten degrading enzymes (alpha-amylase, xylanase and protease), in breadmaking systems. Except glucose oxidase (GO) and laccase (LAC), enzymes affected significantly to viscoelastic properties of dough. Results confirmed the strengthening effect exerted by transglutaminase (TG). However, alpha-amylase (AMYL), xylanase (XYL) and protease (PROT) promoted a similar decrease in all dynamic moduli analysed, particularly after 180 min of incubation. Addition of XYL to TG containing samples showed to be an interesting alternative to prevent excessive dough strengthening. Bread quality parameters were significantly affected by individual enzyme addition, except when LAC was used. TG diminished loaf specific volume and provided a finer crumb structure. Polysaccharide degrading enzymes and PROT led to better shape, greater specific volume and void fraction of loaves. Significant interactions between TG and all the other enzymes except GO, were proved. According to crumb texture evolution during storage, bread staling increased with TG addition, whilst AMYL, XYL and PROT exhibited a significant antistaling effect.

No abstract

Enzymes are used in baking to improve dough handling properties and the quality of baked products. Glucose oxidase (GO) is an enzyme with oxidazing effect due to the hydrogen peroxide released from its catalytic reaction. In this study, the macroscopic effect of increasing glucose oxidase concentrations on wheat dough rheology, fresh bread characteristics and its shelf life during storage was determined. A reinforcement or strengthening of wheat dough and an improvement of bread quality can be obtained with the addition of GO, although inverse effects were obtained when excessive enzyme levels were added. The analysis of the gluten proteins at molecular level by high performance capillary electrophoresis and at supramolecular level by cryoscanning electron microscopy revealed that the GO treatment modified gluten proteins (gliadins and glutenins) through the formation of disulfide and nondisulfide crosslinks. The high molecular weight glutenin subunits showed to be the most susceptible glutenin fraction to the oxidation action of GO. Excessive addition of GO produced an excessive crosslinking in the gluten network, responsible of the negative effect on the breadmaking properties.