Starch Hydrolyzing Enzymes for Retarding the Staling of Rice Bread.

Previous attempts have been made to obtain gluten-free bread of acceptable quality for bread specific volume and crumb texture. Rice bread is a good alternative to celiac patients, but it has a very rapid staling during storage. Rice starch is more prone to retrograde during storage than wheat starch, and the special hydrophobic nature of the rice proteins requires specific enzymes to be used in the rice bread process. To retard rice bread staling, two different starch hydrolyzing enzymes (alpha-amylase of intermediate thermostability and cyclodextrin glycoxyl transferase [CGTase]) have been tested and their effect on fresh bread quality and staling during storage has been evaluated. The addition of alphaamylase improved bread specific volume and crumb firmness but very sticky textures were obtained. The addition of CGTase produced even higher specific volume and similar crumb firmness with better texture. Both enzymes decreased the ability of amylopectin to retrograde during storage. The firming kinetic was lowered by the alpha-amylase but not the limiting firmness, while the rice crumb from CGTase firmed quickly with a very short range of firmness increase. Results revealed that the starch hydrolysis brought about by the alpha-amylase was not sufficient to retard staling. CGTase was considered a better antistaling agent because of its starch hydrolyzing and cyclizing activity.