Rice paste viscosities and gel texture resulting from varying drying and tempering regimen

摘要

Background and objectives Heated‐air drying followed by tempering (HAT) is effective for increasing rough rice drying rates without compromising head rice yield (HRY). However, relatively little is known about the specific nature of the effects of HAT regimens on end‐use properties of rice. This study determined the effects of drying air conditions (air temperature and relative humidity) and tempering durations on changes in rice paste viscosities and gel texture. Findings Rice paste viscosities and gel texture were not only dependent on drying air temperature but also on how long the rice was exposed to a given temperature during drying and tempering. Air relative humidity (rh) had an indirect effect on rice end‐use properties. Using different HAT regimens, peak viscosity was altered by 16%, final viscosity by 21%, breakdown by 24%, and setback by >500% compared with control samples. Gel strength was increased by approximately 40% with HAT regimens. Conclusions Heated‐air drying and tempering conditions must be carefully selected, not only to minimize HRY reductions but also to minimize variations in the functional properties of rice intended for specified end uses. Likewise, HAT regimens could be selected to produce desired properties for specified end uses. Significance and novelty Inconsistencies in rice flour functionality are a hindrance to an expansive use of rice in end‐use, gluten‐free product development. This study shows that drying, a critical postharvest operation, could introduce variations in rice flour quality, which also implies that HAT regimens could deliberately be utilized to produce flour for various end‐use applications.