Thermal exposure values for predicting changes in rice end‐use properties during drying

Abstract

Background and objectives Rough rice may incur various degrees of thermal exposure during heated‐air drying, which may cause variations in end‐use properties. This study employed a recently proposed method to quantify thermal exposure incurred during drying and its effects on rice end‐use properties. Findings Greater drying air temperatures and longer drying durations increased thermal exposure (GATE) values; the higher the GATE value, the more moisture lost during drying. Increasing GATE values reduced head rice yield (HRY). The most notable (≥10%) reductions in HRY occurred when GATE values were ≥30 min. Additionally, increasing GATE values increased peak and breakdown viscosities of rice but decreased both setback viscosity and rice gel strength; the impact of drying on end‐use properties was of most practical importance (≥10% change) when GATE values were ≥40 min. Conclusions The proposed GATE values would permit comparisons of the effects of thermal exposure on rice milling and end‐use properties to facilitate predictions of changes in these properties due to heated‐air drying. Significance and novelty Differences in heated‐air drying conditions contribute to the inconsistencies in functionality that hinder the wide use of rice in end‐use, gluten‐free product development. This study shows that thermal exposure (GATE) values could be useful for quantifying and comparing cumulative heat‐exposure during drying to facilitate predictions of changes in rice properties.