| The quality and safety of traditional Chinese medicines (TCMs) are crucial for warranting the healthy, stable and sustainable development of TCM modernization, as well as for obtaining the equal international status with western medicines. However, in recent years, various mycotoxins have been detected in TCMs, resulting in serious threats to the quality and safety of TCMs, as well as to people’s health and lives. Mycotoxins, the secondary metabolites produced by fungi, have been considered as one of the major toxic and harmful exogenous substances in TCMs. The intracorporal accumulation of mycotoxins would cause cancers, and other toxic and side effects to the liver and kidney. During the processes of growth, harvesting, processing, especially storage, TCMs, under the influences of their own inner factors and the environmental conditons, are easily to become mouldy to be contaminated by mycotoxins. Scientific preservation of TCMs is very important to prevent them from being contaminated by mycotoxins, further to ensure the quality and safety of TCMs and their related products.So, in this thesis, with malt, lotus seed and nutmeg as the selected targets, and the charactersistics, the contents of moisture, mycotoxin and chemical components as the evaluated indexes, the changes of becoming mouldy and inner qualities of malt, lotus seeds and nutmeg stored under different temperature and humidity conditions, as well as in various packing materials were studied. The aim was to explore the best storage condition for preventing mycotoxins contamination to ensure the safe use of TCMs, further to provide valuable references for the establishment of storage specification for TCMs. The main results were described as follows:1. Establishment of UHPLC-MS/MS method for the determination of mycotoxins in malt, lotus seed, and nutmeg samplesA suitable ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) method was developed for the determination of 11 mycotoxins with isotope internal standard in malt, lotus seed, and nutmeg. Due to the differences of types and properties of mycotoxins in TCMs, the uses of improper pre-treatment methods will inevitably cause losses of some mycotoxins. Herein, the mycotoxins in tested samples were extracted and purified twice by using the one-step ultrasonic extraction procedure, then were directly injected for analysis to ensure the accurate quantitation. With isotope labeled AFB1 ([13C17]-AFB1) and ZEN ([13C18]-ZEN) as the internal standards, some possible errors generated in the process of mass spectrometry analysis could be avoided to improve the reliability of the method. Then, the established method was further validated in terms of linearity, sensitivity, average recovery, precision and matrix effects. The validated method was further successfully applied for the trace determination of 11 mycotoxins in 20 malt,10 lotus seed and 10 nutmeg samples. The results showed that 8 malt samples were positive for mycotoxins including AFB1, T-2 toxin, fumonasin B2(FB2), ochratoxin A (OTA) and deoxynivalenol (DON).3 lotus seed samples were detected with mycotoxins including AFB1, T-2 toxin, FB2 and ZEN. And only one nutmeg sample was examined with AFB1. These studies have demonstrated that the UHPLC-MS/MS method was simple, quick, accurate and sensitive for the analysis of multiple mycotoxins in complex matrices after one-step extraction.2. Establishment of analytical method for the determination of multi-components in malt, lotus seeds, and nutmeg samplesTwo ultrasonic extraction based LC-TOF/MS methods were established, respectively, for the quantitation of hordenine in malt, and liensinine, isoliensinine and neferine in lotus seeds. In addition, a GC-MS/MS method was developed for the simulataneous quantitation of six components in essential oil of nutmeg, and the stable fragment ions of the six components were obtained based on the optimization of the extraction procedure and GC-MS/MS method.3. Study on the preservation methods for malt, lotus seeds, and nutmeg during their storage processWith the characteristics, and the contents of moisture, mycotoxin and chemical components as the evaluated indexes, the changes of becoming mouldy and inner qualities of malt, lotus seed and nutmeg stored under different temperature and humidity conditions, as well as in various packing materials for one year were investigated. It was suggested that the plastic bag was the preferred packaging material for the storage of malt, lotus seed, and nutmeg. The packaged samples should be placed under shady and cool, dry, dark, ventilative conditions or indoor environment. In addition, different woven bags or kraft bags should be selected for malt, lotus seeds, and nutmeg, respectively.4. Formulating the storage specification for malt, lotus seed, and nutmeg based on composite design-response surface method and the trans-cultivation modeBased on the CCD-RSM method and the trans-cultivation mode, the optimized storage conditions for malt, lotus seed, and nutmeg were investagated to provid references, further to formulate the storage specification. The susceptible fungal contamination condition in malt, lotus seed, and nutmeg were identified by CCD-RSM method as temperature of 22-37℃ and humidity over 87.5%. Particularly, when the environmental temperature was set at 30℃ and humidity at 95%, the highest contents of aflatoxins were found in malt, lotus seed, and nutmeg samples. Thus, to prevent the production of fungi, the three TCMs were suggested to be stored at temperature below 20 ℃ and humidity lower than 85%.Our study have also ellucidated that lotus seed was easily to be contaminated by aflatoxins under high temperature and humidity conditions during the storage process, while it was not so obvious for malt and nutmeg. Low temperature and humidity conditions were welcomed for the storage of the three TCMs for preventing the production of mycotoxins. |
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