Experimental study on drying characteristics of rice by low‐field nuclear magnetic resonance
Hongchao Wang, Gang Che, Lin Wan, Menggang Liu, Wen-sheng SUN
Abstract
Abstract This article is purposed mainly to analyze the drying characteristics in the internal moisture of rice at different drying temperatures using low‐field NMR. The signals of the relaxation time were applied to determine the moisture content and dynamic characteristics of various phases. According to the experimental results, the migration of strongly chemically bound water and other phases of water was a bi‐directional process. The first half of the process can be dried at high temperatures to remove moisture rapidly, while the second half can be lowered to reduce the moisture gradient. Besides, the first half was dried at 65°C and the second half at 35, 45 and 55°C, which led to an increase in energy consumption by 9.62%, 6.99%, and 2.54% as well as an extension to the drying time by 65, 40, and 18 min. The results will provide a theoretical basis for optimizing the drying process for rice. Practical Applications Low field nuclear magnetic resonance was applied to study the drying characteristics of rice, and to determine the variation pattern and migration characteristics of water in different phases of rice with varying temperatures during the drying process. On this basis, a high‐quality variable temperature drying method was proposed. Moreover, this method is applicable to the variable temperature of the rice drying process.