Rheology of Rice‐flour Pastes: Relationship of Paste Breakdown to Rice Quality, and a Simplified Brabender Viscograph Test

Flours from 21 nonwaxy rice cultivars, varying in amylose‐equivalent (AE) content and eating quality, were pasted at 12–13% concentration at 95C and then further cooked at the same temperature for another 60 min. The fall in apparent viscosity, measured in a coaxial cylinder viscometer, of the 95C–50 min as compared to that of the 95C–0 min paste (paste breakdown, bd p ) was calculated. The bd p values were inversely correlated to the sensory and viscoelastograph hardness of cooked rice as well to the AE contents. Paste breakdown was clearly a fundamental attribute of rice quality. It appears that starch granule rigidity/fragility, as determined by its AE, is the basic element in rice quality. This principle was then used to devise an abridged Brabender viscograph procedure. The slurry concentration was adjusted, by a simple technique described, to give a predetermined viscosity value at 95C. Then the paste was heated for another 10 min at 95C. The breakdown at 95C (BD 95 ) of the samples correlated excellently with their total and insoluble AE, sensory and instrumental measures of cooked‐rice texture, and with bd p .