Location: Healthy Processed Foods ResearchTitle: Improvement in storage stability of infrared dried rough rice Author
|Ding, Chao - NANJING UNIVERSITY OF FINANCE AND ECONOMICS|
|Khir, Ragab - UNIVERSITY OF CALIFORNIA|
|Wood, Delilah - De|
|Tu, Kang - NANJING AGRICULTURAL UNIVERSITY|
|El-mashad, Hamed - UNIVERSITY OF CALIFORNIA|
Submitted to: Food and Bioprocess Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2016
Publication Date: 2/16/2016
Citation: Ding, C., Khir, R., Pan, Z., Wood, D.F., Tu, K., El-Mashad, H., Berrios, J.D. 2016. Improvement in storage stability of infrared dried rough rice. Food and Bioprocess Technology. 9(6):1010-1020.
Interpretive Summary: The objective of this study was to investigate the effect of infrared (IR) drying followed by tempering and natural cooling on the change of physicochemical characteristics of rough rice during up to 10 months of storage. Besides the high drying rate and milling quality of rice obtained by using IRD as our previously reported, this research also showed that IRD had positive effects on the stability of rice color, microstructure, gelatinization, pasting, and cooking and texture properties. After 4 months of storage, the increments of yellowness index, water uptake, and volume expansion ratio of the rice samples dried with IRD were respectively reduced to 73.7%, 23.7% and 85.5% of those dried with ambient air. The denaturation and annealing effect of IRD on protein and starch could reduce the changes in microstructure, the gelatinization temperature, enthalpy and viscosity. The physicochemical properties were better maintained during storage for the rice dried by IR.
Technical Abstract: The objective of this study was to develop infrared drying (IRD) method to improve the stability of physicochemical properties of rough rice during storage. The effect of IRD on the physicochemical properties of stored rough rice was compared with that of hot air drying (HAD) and ambient air drying (AAD). Freshly harvested M206 rice was dried to a targeted moisture content of 16% by using IRD, HAD, and AAD. The dried rice samples were then stored at 35.0±1.0°C and a relative humidity of 65.0±3.0% for up to ten months. The physicochemical and cooking properties of rice samples were periodically determined over the storage duration. Compared with AAD, the rough rice dried with IRD and stored for 4 months, yellowness index, water uptake and volume expansion ratio were reduced by 26.3%, 76.3% and 14.5%, respectively. IRD likely caused a slight denaturation of protein and annealing of starch that located on the surface layer of rice kernels, resulting in decreased gelatinization temperature, enthalpy, viscosity, and reduced the changes in microstructure, but retained cooking characteristics after storage. Therefore, IRD is recommended as a promising technique that achieves high rice drying efficiency and improved stability of physicochemical properties of rice during storage.