Physicochemical quality improvement of dried rice noodles by direct heat-moisture treatment during the drying process

Abstract

In view of the advantage of heat-moisture treatment (HMT) in modifying the properties of starchy materials, the purpose of this study was to explore the effects of directly applying HMT during the drying process on the properties of dried rice noodles. As attained to prescribed moisture content (20%–35%), the rice noodles were subjected to HMT at 110 °C for 2 h. By HMT, the dried rice noodles exhibited greater structural orderliness and thermal resistance. The relative crystallinity increased from 8.73% to 11.50% and the short-range order (the absorbance ratio of 1047 cm⁻¹/1022 cm⁻¹) increased from 0.57 to 0.72. On the contrary, the lamellar thickness, the radius of gyration, and the mass fractal dimension and pasting viscosities were lowered. Then, HMT induced dried rice noodles with restricted starch leaching during rehydration and reduced cooking loss. HMT increased microstructure homogeneity and texture properties of the cooked rice noodles. Notably, the heat-moisture treated rice noodles at 20% moisture content showed a significant higher cooking yield, about threefold of extensibility, and 1.68 folds of chewiness than the control. Our findings, if generally applicable to the processing of rice noodles, could offer a streamlined approach to increasing the quality of dried rice noodles.