The Application Of NMR And MRI In The Process Of Growth And Storage In Navel Orange

Always people have been aware the relationship between moisture content and easy corruption in food, and through concentration and dehydration process which can effectively extend the shelf-life of food. However, the types of food is different, even if have the same moisture content, but have different corruption. If we can take the effective methods to control the moisture migration in food, which will improve the stability of product and have positive significance for the shelf-life of food. Therefore, it is necessary to study the role of water and the migration behavior of water in food, as this will have important guiding significance for food processing and the mechanism of preservation. NMR&MRI is an effective method to study molecular diffusion, it can research the molecule of water fat and sugar in food system, these molecule often carry some important message: structural information, elements in their environment information, the information of food processing and the internal change and so on, and NMR technology which have feature of nondestructive testing technology the technology used in food science to the study has obvious advantages.The overall objective of my thesis was to develop Nuclear Magnetic Resonance (NMR) relaxometry and Magnetic Resonance Imaging (MRI) based techniques to study the processing of growth and storage of navel orange. In thesis, we have explained the relationship between main chemical components and NMR parameters. At different ways of dealing and temperatures, the NMR parameter changes in properties during navel orange storage, and approaching the corruption mechanism from the micro-degree.The first part of the main article was to study the growth process of navel orange, the results showed that relaxation time T2* was slow downward trend with the growth, it showed that the capacity of macromolecular materials combination water to reduce, and macromolecular material consumed more than generated material. Relaxation time T21 and T22 with the main chemical components higher and higher values in the early time, the latter part greater impact on the free water. Internal navel orange, the main water exist as free state , this part of water have the longer relaxation time T23. Growth in the process of navel orange, the T23 relaxation property changes more significantly, the trend has been on the increase, which promoted the T21 and T22 representative of the water activity with water until closed to maturity. Internal navel orange the different relaxation time of representative different existence state water, the relaxation time T21, T22 and T23 become stable and the role result of the various physical and chemical indicators gradually formed a special Orange flavor, fruit can be picked. Through correlation analysis showed that between variables have the correlation, and the relationship between acidity and total sugar and relaxation time T21, T22 and T23 have significantly correlated (p <0.05), the variables are highly significant. The result of-correlation analysis further explain using NMR relaxation time judgment the relationship between he physical and chemical indicators and mature of fruit has certain reliability, meanwhile explain moisture migration movement is an important factor to judgment fruit mature in navel orange. And through MRI images can be directly reflected internal proton density changes during growth of navel orange.The second part of the main article was to study navel orange with different treatment, the trend of magnetic resonance parameters and the physical and chemical properties, the results showed: although different approach, had the same trend line, according the relaxation time of change trends, we divided navel orange storage process into three phases: after maturity, stable and decomposed period. During navel orange storage, T23 increased and the activity of small molecules increase, due to the impact of respiratory metabolism, consumption more small molecule material during storage. Despite the loss of moisture, the free moisture content increase, water-poietic outweigh the losses; we found that navel orange with water dealing having the shortest storage period about 60 days. From magnetic resonance parameters we saw that navel orange using of 2,4-D plus carbendazim, fruit wax and ozone water treatment could extend storage period about 20 days at least. From the magnetic resonance parameters T21 and T22 of the navel orange investigate corruption mechanism, we believe that macromolecular material degradation for small molecular materials, the peel lost water holding capacity and form free water more than water consumption was the main influencing factors in addition to microbial role.The third part of the main article was to study the navel orange storage at different temperature, in the storage period the change of moisture situation. The result showed that the navel orange storage at low temperature with a longer storage time and lower T21, T22 and T23 relaxation time values, and explain storage at low temperature can inhibite effectively the mobility of water which is material for the quality change of navel orange, conducive to the storage of navel orange and extension of its storage period. From proton density, small molecule sugar and water is metabolites, which promoted the strength of NMR signal, and the navel orange storage under low temperature has higher proton density than navel orange under room temperature, so having high proton density, it is the reason that low-temperature storage with longer time from proton density. Using SPSS 11.5 statistical software analysis found the probability P value of less than 0.01 between the combined result soluble solids content and relaxation time T23 and corresponding proton density, and among them having highly significant and the impact of the relaxation time greatest.