Xiangli Kong1,2, Dan Qiu3, Xiaoting Ye4, Jinsong Bao1, Zhongquan Sui4, Jiewei Fan5, Wenzhou Xiang5. 1. Institute of Nuclear Agricultural Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China. 2. Engineering Research Center of Starch and Vegetable Protein Processing, Ministry of Education, South China University of Technology, Guangzhou 510640, People's Republic of China. 3. College of Chemical Engineering, Ningbo University of Technology, 89 Cuibai Road, Ningbo, Zhejiang 315016, People's Republic of China. 4. Department of Food Science and Engineering, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China. 5. CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, Guangdong, People's Republic of China.
Abstract
BACKGROUND: Currently there is much interest in the application of physical modification techniques such as heat-moisture treatment (HMT). The effects of HMT on normal and waxy rice starches, subject to different levels of moisture content and duration of heating, were investigated. RESULTS: Water solubility index (determined at 90 °C) decreased after HMT for normal and waxy rice starches, while swelling power (determined at 90 °C) showed inconsistent results (decrease for normal type, increase for waxy type) after HMT. Values in pasting parameters of normal and waxy rice starch increased initially, but the extent of increase slowed down with moisture content and length of treatment increasing. HMT decreased gelatinization temperatures with 4 h and 8 h treatment, but when length of treatment was prolonged to 16 h gelatinization temperature increased. Degree of crystallinity decreased for all treatments, and decreased much more at higher levels of moisture content. CONCLUSION: Variations in levels of moisture content and duration of heating had significant effects on physicochemical and crystalline properties to different extents.
BACKGROUND: Currently there is much interest in the application of physical modification techniques such as heat-moisture treatment (HMT). The effects of HMT on normal and waxy rice starches, subject to different levels of moisture content and duration of heating, were investigated. RESULTS:Water solubility index (determined at 90 °C) decreased after HMT for normal and waxy rice starches, while swelling power (determined at 90 °C) showed inconsistent results (decrease for normal type, increase for waxy type) after HMT. Values in pasting parameters of normal and waxy ricestarch increased initially, but the extent of increase slowed down with moisture content and length of treatment increasing. HMT decreased gelatinization temperatures with 4 h and 8 h treatment, but when length of treatment was prolonged to 16 h gelatinization temperature increased. Degree of crystallinity decreased for all treatments, and decreased much more at higher levels of moisture content. CONCLUSION: Variations in levels of moisture content and duration of heating had significant effects on physicochemical and crystalline properties to different extents.