Viscoelastic properties and bubble structure of rice-gel made from high-amylose rice and its effects on bread

Rice gel is a novel form of processed rice, where gelatinized rice is sheared at high speed to create a gel with unique viscoelastic properties, which can partially replace wheat flour in bakery products. In this study, the viscoelastic properties and bubble structures of rice gels made from two high-amylose rice cultivars and two different ratios of rice to water were studied, focusing on the effect of cooling the gelatinized rice before high-speed shearing (cooled rice gel) as opposed to shearing the gelatinized rice while hot (hot rice gel). Increasing the water content and cooling the rice before high-speed shearing generally decreased the dynamic storage (E′) and loss moduli (E″) in the viscoelasticity measurement and introduced fewer but larger and uniform bubbles in the rice gel. In addition, breads made from cooled rice gel showed significantly higher volume than those made from hot rice gel. The application of mechanical shearing to gelatinized starch has a great potential in creating novel food materials with characteristic textures, and can also be used for the processing of cereals other than rice.