Study On Aroma Compounds Of Orange Juice And Geographical Origin Method Research By PTR-MS

Proton transfer reaction mass spectrometry(PTR-MS)is a new kind of mass spectrometry,which is developed in the middle of the nineties of the 20 th century.Because of its advantages of high sensitivity,fast response,good specificity,without pretreatment,being analyzed quantitatively and so on,it can be used in many domains such as medical and health care,food science,and atmospheric environment,and has got extensive development and application.This study is based on the major scientific instruments and equipment project "proton transfer reaction mass spectrometer device development and application demonstration" of ministry of science and technology.On the principle of proton transfer reaction and concentration calculation,some important parameters of proton transfer reaction are listed.The structure design and the performance evaluation of ion source and drift tube of the PTR-MS are studied.Through ion optical analysis software,simulations of different types of structure of drift tube are studied.Influence on the uniformity of internal electric field distribution and the movement trajectory of ions in the drift tube are analyzed.Sampling system for liquid tests is studied.The overall performance and optimization of the instrument are evaluated on three aspects of pneumatic control,selection of quality analysis and ions detection.Volatile organic compounds of orange juice are measured by PTR-MS instrument,and analyzed on its material composition.There are certain differences between aroma substances in the chemical compositions and the absolute density of citrus squeezed orange juice from different regions and different varieties.At the same time it can provide theoretical basis for establishing the volatile aroma of orange juice mass spectrometry library.Methods of principal component analysis and fisher discriminant analysis are respectively used to distinguish four citrus juices from Chongqing and five regions of navel orange juice from Chongqing,Fujian,Hunan,Jiangxi and Guangxi.Function models to distinguish different kinds and different regions of orange juice are established,and so is the function model to estimate unknown sample types of orange juice.