Effect of different pressure-soaking treatments on color, texture, morphology and retrogradation properties of cooked rice

Abstract

The hydration of rice grain and the quality of cooked rice with the different pressure soaking treatments were estimated using Chroma meter (CM), Texture Profile Analysis (TPA), Scanning electron microscopy (SEM), and Differential Scanning Calorimetry (DSC). The results showed that the vacuum soaking and the high hydrostatic pressure (HHP) soaking increased the hydration degree of normal rice, while the hydration effect in waxy rice was increased only by the HHP treatment. The lightness (L*) and the color intensity (B) of cooked normal rice and waxy rice were significantly improved by the two treatments. The HHP soaking also generated the lower hardness, while the higher springiness and cohesiveness for cooked normal and waxy rice samples. These highlights were mainly attributed to the less amylose leaching and the smaller network channels formed between starch granules and other connection parts. Furthermore, the retrogradation of cooked normal and waxy rice was reduced by the HHP treatment. These findings suggest that the HHP soaking could be used for producing high-quality of cooked rice.