Hydrothermal treatments of rice starch for improvement of rice noodle quality

Effect of acid hydrolysis combined with heat moisture treatment on structure and physicochemical properties of corn starch

Modification of starch led to new products with new desirable properties. Corn starch samples modified by acid hydrolysis combined with heat moisture treatment (AH-HMT) were made by changing pH, moisture content and treated temperature. After modification, swelling power at temperature higher than 75 °C of corn starches decreased while solubility of the starches increased. After AH-HMT, pasting temperature (PT) of all treated starch samples increased. But lower peak viscosity (PKV), trough viscosity (TV) and break down (BD) of most treated starch samples were observed. AH-HMT increased the gel hardness of all treated starches. And the biggest hardness of modified starch gel was 148.419 g, improving 93.471 g compared with native starch gel. The melting temperatures (To, Tp, Tc) of modified starch increased, but the melting range and △H decreased. The X-ray pattern remained practically unchanged with or without AH-HMT. Acid hydrolysis combined with heat moisture treatment (AH-HMT) improved the functional properties of corn starch.

The effect of heat moisture treatment on physicochemical properties of early indica rice

Early indica rice was heat-moisture treated at different temperature (90°C, 100°C and 110°C) for 3h, 5h and 7h at a moisture content of 28%, respectively. The effects of heat-moisture treatment (HMT) on the amylose content, pasting properties, texture properties, solubility and swelling power of early indica rice were studied. After HMT at 110°C for 7h, the amylose content of early indica rice increased from 25.2% to 30.6%, and its pasting temperature increased from 80.1°C to 92.2°C; the peak viscosity, trough viscosity and final viscosity were all decreased significantly. Both the solubility and the swelling power of early indica rice starches decreased after 110°C 7h heat-moisture treatment. The gel hardness of early indica rice increased significantly, but the adhesiveness decreased after HMT.

Effects of heat-moisture treatment on normal and waxy rice flours and production of thermoplastic flour materials

Different levels of heat-moisture treatment (HMT) were applied to normal and waxy rice flours. Changes in chemical composition and functional properties of both flours were investigated. It was found that HMT induced β-turn conformation of rice proteins. Levels of HMT and types of rice flour interactively influenced thermal properties and XRD patterns of flour. When heat-moisture treated flour was utilized for production of thermoplastic flour (TPF) materials, it was found that HMT improved continuity of injection molding, complete mold filling, and yielded homogenous TPF materials. HMT levels affected the mechanical, thermal and barrier properties of TPF resin and materials differently. The ratio of HMT level to native flours was proposed for use not only for resin processing and injection molding, but also for improving mechanical and barrier properties of TPF materials.

The impact of single and dual hydrothermal modifications on the molecular structure and physicochemical properties of normal corn starch

Effect of single and dual hydrothermal modifications with annealing (ANN) and heat-moisture treatment (HMT) on molecular structure and physicochemical properties of corn starch was investigated. Normal corn starch was modified by ANN at 70% moisture at 50 degrees C for 24h and HMT at 30% moisture at 120 degrees C for 24h as well as by the combination of ANN and HMT. The apparent amylose content and swelling factor (SF) decreased on ANN and HMT, but amylose leaching (AML) increased. These changes were more pronounced on dual modification. The crystallinity (determined by X-ray diffraction), the gelatinization enthalpy (determined by differential scanning calorimetry) and ratio of 1047 cm(-1)/1022 cm(-1) (determined by Fourier transform infrared spectroscopy) slightly increased on ANN and decreased on HMT. The ANN and subsequent HMT (ANN-HMT) resulted in the lowest crystallinity, gelatinization enthalpy and ratio of 1047 cm(-1)/1022 cm(-1). The gelatinization temperature range decreased on ANN but increased on HMT. However, the gelatinization range of dually modified starches (ANN-HMT and HMT-ANN) was between ANN starch and HMT starch. Birefringence remained unchanged on ANN but slightly decreased on HMT as well as dual modification. Average chain length and amount of longer branch chains (DP> or =37) remained almost unchanged on ANN but decreased on HMT and dual modifications (ANN-HMT and HMT-ANN). HMT and dual modifications resulted in highly reduced pasting viscosity. ANN and HMT as well as dual modifications increased RDS content and decreased SDS and RS content.