Influence of the viscoelastic properties of rice dough on the mechanical properties and the microstructure of rice crackers was experimentally investigated to predict and control the quality of the rice cracker in the early stage of the lengthy manufacturing process. Various rice doughs steamed for 5, 30, or 60 min and kneaded for 5, 10, or 15 min were examined. Longer steaming and kneading resulted in lower G' and G″ and higher tan δ, specific volume of the rice crackers, decreased nonuniform and deficient network, and thinner cell wall in rice cracker sections. There was a high correlation between tan δ of rice dough and specific volume of the rice cracker samples (R2 > 0.79). The hardness of the rice crackers increased with extending the kneading time for 5 and 30 min as the tan δ increased, while those of the rice crackers made from the rice doughs steamed for 60 min decreased inversely. These results indicated that qualities of rice crackers can be predicted and quantified by measuring viscoelasticity of actual rice doughs during the process. PRACTICAL APPLICATIONS: Improved methods to control quality of end product in manufacturing process and to develop new products with unique textures are desired. We established the new method to quantify the rice dough and this method has already been used for confirming equivalency or improvement of rice dough during manufacture of rice crackers when instrument or condition have changed.
Keywords: hardness; rice cracker; rice dough; specific volume; viscoelastic properties.
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