ABSTRACT
One of the main problems associated with gluten-free bread is obtaining a good structure. Transglutaminase (TGase), an enzyme that catalyzes acyl-transfer reactions through which proteins can be cross-linked could be a way to improve the structure of gluten-free breads. The objective of this study was to evaluate the impact of TGase at different levels (0, 0.1, 1, and 10 U of TGase/g of protein) on the quality of gluten-free bread. The recipe consisted of white rice flour (relative amount: 35), potato starch (30), corn flour (22.5), xanthan gum (1), and various protein sources (skim milk powder [SMP] [12.5], soya flour, and egg powder). The influence of the various proteins in combination with the different addition levels of TGase on bread quality (% bake loss, specific volume, color, texture, image characteristics, and total moisture) was determined. Confocal laser-scanning microscopy (CLSM) was used to evaluate the influence of TGase on the microstructure of the bread. Baking tests showed that TGase had an effect on the specific volume of the bread. For instance, the SMP bread with 10 U of enzyme contained the most compact structure, which was reflected in the crumb texture profile analysis results (highest values) (P < 0.05), digital image analysis (highest level of cells/cm2) (P < 0.05), and CLSM micrographs (network formation). Finally, it can be concluded that it is possible to form a protein network in gluten-free bread with the addition of TGase. However the efficiency of the enzyme is dependent on both the protein source and the level of enzyme concentration.
