Study Of Water Contect Detection In The Rice Seed Soaking Process Based On Low Field NMR Techniques

To study the water phase state, distribution characteristics, and flow rules of rice seed during the soaking process, the technology of low field nuclear magnetic resonance in-situ nondestructive testing and the method of continuous soaking, intermittent soaking, medical soaking and hot water treatment were used to research the soaking process of different varieties rice seeds.The water phase inside of the seed was distinguished by the characteristics of multiple components of the transverse relaxation time T2;The moisture change and flow pattern of rice seed were analyzed by the difference of the amplitude of T2 relaxation spectrum;The quantitative research on rice seed soaking was studied by the relational model of transverse relaxation time, water phase, water stratification and relaxation spectrum signal amplitude with the moisture content. This study presents a nondestructive method of moisture detection, the change and transfer of rice seed moisture can be more directly and accurately revealed the in the soaking process, it provides data support and theoretical basis for the best soaking conditions of rice seeds and the model construction of water transfer in the process of seed soaking.The research contents, results and conclusions of this paper are summarized as follows:(1) To study the water phase and distribution characteristics of rice seed in soaking process, the detection technology of low field nuclear magnetic resonance was used which was fast, nondestructive and accurate. The transverse relaxation time T2 of rice seed was measured through the Carr-Purcell-Meiboom-Gill sequence (CPMG), the inner water phase and its change rules were distinguished according to the difference transverse relaxation time T2.Test results show that:it found that the internal moisture of rice seeds in soaking process exists two states, bound water and free water, and presents three water stratification, inner, middle and outer water by different length T2 spectrum inversion of transverse relaxation time T2;Both water state and stratification can estimate water absorption rate through the regression equation; it also found that the total water content of rice seed continues to rise in the process of soaking by the difference of T2 inversion spectrum signal amplitude, but because of the different ways of judgment and classification, there was a slightly different in the way of water flow. Low field NMR intuitively reveals the changes of water inside the rice during seed soaking process, and also provides an efficient seed moisture detection method.(2)The technology of nuclear magnetic resonance which has the advantage of non-destructive, non-invasive was used to study the change of rice seed moisture during soaking. The change and flow process of different moisture state was analyzed by the multi-component characteristics of relaxation time and relaxation spectrum. The change of water content in seed soaking process was studied by the regression equation of total peak area and water absorption rate. Shennong No.9816?Qishanzhan and Xiuzinuo were soaked 48 hours monitored by using low field nuclear magnetic resonance. Transverse relaxation time T2 inversion spectrum was collected by CPMG sequence each 6h, so as to analyze the effects of soaking process on moisture distribution of internal rice seed. The results show that the water absorption rate of rice seeds can be reasonably estimated by the peak area of the relaxation spectrum; In the 6h seed soaking process, the content of bound water and total water were increasing with the immersion time but free water showed irregular changes.It found that the highest water absorption rate was Xuizinuo and the lowest is Shennong 9816 according to the T2 spectrum inversion signal amplitude, during the same soaking time. The test results show that the water absorption of amylopectin is better than amylose.(3) The changes of water absorption during soaking process was studied by using the technology of low field nuclear magnetic resonance in-situ nondestructive testing and the method of continuous soaking, intermittent soaking, medical soaking and hot water treatment.The changes of water state and absorption characteristics were analyzed by the transverse relaxation time T2 inversion in the soaking process. The test results showed that the internal moisture distribution of rice seeds was changed by soaking process, the water absorption of rice seed was highly sensitive to various water soaking method, but not to the initial moisture. By the intermittent soaking methods of soaking 2h, dry 1h, soaking 2h,40% formalin and 50 times medicament liquid and improving the soaking temperature could increase the water absorption of rice seed in soaking process; By the intermittent soaking methods of soaking 3h, dry 1h, soaking 1h, saturated lime water and 300 times strong chlorine liquid could reduce the water absorption; With the increasing temperature of seed soaking, the water absorption was significantly enhanced. The test provides an effective method for the determination of water content in rice seed soaking process, also provides data support and theoretical basis for seeking the best soaking condition.(4) To study the internal moisture flow of rice seed in soaking process and visualize the internal moisture transfer process, the low field NMR and MRI techniques were used to monitor the soaking process of Shennong No.9816, Qishanzhan and Xiuzinuo in 48h. Spin echo, (SE) pulse sequence was used to obtain the proton density weighted image each 6h, so as to analyze the effects of soaking process on rice seed internal moisture distribution. The test results show that NMR is an effective moisture detection technology, the internal moisture distribution and dynamic flow of seeds can be directly detected by the proton density weighted image. It found that water entered the seed originally from the embryo, and finally reached the endosperm by the permeability of seed coat. The research results can provide data support for the theoretical model construction of water transmission of rice seed during the process of soaking.