| Rice is the most important food crop in China.The drying method and internal quality of rice seeds will directly affect the emergence of rice seedlings and seedling properties during seasonal cultivation,and have an important impact on the yield of food crops.In order to study the change and flow of water during drying and drying of rice seeds,this paper,based on the LF-NMR technology,uses the spectrum and imaging test of Nuclear Magnetic Resonance instrument.Qualitative and quantitative visualization of water transfer in rice seeds during drying was studied.In addition,as food adulteration is profitable in recent years,adulteration and insufficient purity of rice seeds are more common.Rice seeds with low vigor level are indistinguishable from normal seeds in appearance,and are often mixed into seeds with good quality and high vigor,which cannot be distinguished and detected by naked eyes.In this paper,LF-NMR technology was used to analyze the lateral relaxation distribution curve of rice seeds with different adulteration ratios,combined with stoichiometry,to explore the identification of adulteration of rice seeds,providing a scientific and rapid new method for seed adulteration identification.The main research content,test process,test results and conclusions of this paper are summarized as follows:（1）In order to study the change and flow of water in rice seeds during drying,LF-NMR technology was used to dry rice seeds on cement floor.The NMR echo signal and attenuation data of the samples were measured by LF-NMR hard pulse echo sequence CPMG.With inversion analysis software,the transverse relaxation time T2and the relaxation map of the inversion data were obtained.The differences and changes of transverse relaxation time T2were used to distinguish the existence and mutual transformation of water within seeds.The test results showed that the most ingredient was bound water,while the semi-bound water and free water proportion were very little.With the uninterrupted growth of drying time,the content of bound water shows a important decrease,while the content of semi-bound water and free water does not change much.There is a certain infiltration and mutual transformation between different states of water when the external environment is unstable.（2）In order to judge the internal water flow of rice seeds during drying,LF-NMR imaging software was used to obtain intermittent proton density weighted images.According to the light and dark area signals of image data,the water distribution inside the seeds could be clearly distinguished.The results showed that the brightness of seed embryo was the highest,which proved that the water content of rice seed embryo was the highest.The brightness of seed coat was second,indicating that the epidermis had a high moisture content due to water exchange and moisture retention with the outside world.The endosperm part is the darkest,which proves that endosperm is mainly composed of starch,the material structure is single,the water content is the least.Through continuous observation before and after days of dry LF-NMR pseudo color map,is the first remove found adhered on the surface of the seed of the free state of water,followed by the capillary to the seed surface transfer inner moisture,the water stored up used for embryo also lost moisture germinate.（3）In order to study the identification of adulteration and identification of different adulteration ratios of rice seeds,this study used LF-NMR technology to add artificially aged inactive rice seeds into normal viable rice seeds at different ratios.Five gradient adulteration samples with adulteration ratios of 0%,30%,50%,70%and 100%were obtained,and the data of the adulterated samples in each group were collected and processed by NMR.The results showed that LF-NMR could distinguish the different adulteration ratios of rice seeds.For seeds with high adulteration rate and poor vigor level,the signal amplitude A21of T21peak area was getting smaller and smaller,indicating that seed binding water content was getting less and less.The peak area A22of the initial time of the transverse relaxation time T22showed no obvious change,indicating that the free water level did not change significantly.It was proved that LF-NMR data can quickly distinguish the adulteration of rice seeds,providing fast,accurate and non-destructive theoretical basis and technical support for seed adulteration identification.（4）Based on the above data statistics of adulteration results,two chemometrics methods,PCA and systematic clustering Analysis,can be used to obtain the data classification information of each adulteration gradient.Measurement results show that the rice seed samples of different adulteration ratio on the PCA scoring diagram and the system tree graph are showing a clear separation of different adulteration ratio obtained the very good distinguish,presents a certain regularity distribution,detailed classification,clearly visible and higher identification accuracy,fast for rice seed adulteration recognition,standardize the rice seed market provides a good basis. |
