Study On Traceability Of Core Origin And Low Temperature Preservation Technology Of Lu'an Guapian Tea

The existing protection standards for the geographical indication products of Lu'an guapian tea include the entire Lu'an city,while the actual production of Lu'an guapian tea is divided into inner mountains and outer mountains.The prices between different producing areas are far apart.At the same time,Lu'an guapian tea,a kind of baked green tea made entirely from leaves,is highly susceptible to oxidative deterioration when stored improperly.The discrimination of origin and preservation are two problems that need to be solved in the development of Lu'an guapian tea industry.The experiment collected the Lu'an guapian tea from the three counties(11 villages and towns)of Jinzhai,Huoshan and Yu'an processed at the same time.The main catechins,amino acids and caffeine were quantitatively analyzed by high-performance liquid chromatography.The differences of the three major metabolite contents in the Lu'an guapian tea were combined,and the pattern factors were used to screen out the characteristic factors and establish the discriminant model.A batch of fresh leaves is processed into different moisture(3%,5%,10%)of Lu'an guapian primary tea,stored in room temperature,refrigerated(4?)and frozen(-10?,-20?),regularly sampled into finished tea.Analyze the change of color and component content,the optimal condition of moisture was found,then the metabolomics analysis was adapted to find out the differential metabolites of Lu'an guapian tea between different storage temperature.The main results of the study are as follows:(1)There are differences in the components of the Lu'an guapian tea from different producing areas.The difference between the inner mountain and the outer mountain tea is significant,mainly in the amino acid content of Ile,Phe,Val,Leu and Ser;the content of Met and GA in the county area is difference.Based on the component content in the tea,the method of principal component analysis combined with support vector machine was used to realize the quantitative discrimination between the inner mountain and the outer mountain and among counties of Lu'an guapian tea,and the predictive set discrimination rate of both models reached to 95.83%.(2)During the 12-month storage of Lu'an guapian tea,the content of water extracts has been declining,and the storage of low moisture is not conducive to the retention of water extracts.The content of catechins is also declining during storage.Under the condition of same moisture,the lower the storage temperature,the slower the rate of catechin content decline,the 5%moisture frozen storage can effectively reduce the degradation of catechin.The caffeine changes little during storage.The amino acid content is presented during storage.The trend of rising before and after falling,the treatment group with low moisture is not conducive to the retention of fresh sweet amino acid.The effect of moisture is bigger compare to the storage temperature on the color of dry Lu'an guapian tea.The experiment indicates that the frozen storage of 5%moisture content is most beneficial to the preservation and storage of Lu' an guapian tea.(3)5%moisture of room temperature and low temperature(4?,-20?)storage samples show difference in content of catechins and its dimers,flavonols/glycosides,phenolic acids and organic acid.Specifically,the tea stored at room temperature is significantly higher than that of low temperature storage in content of Myricetin 3-galactoside,Maesopsin 6-glucoside,gallic acid,galloyl glucose and other substances.The low-temperature storage samples were significantly higher than the room temperature storage samples in content of proanthocyanidins,phenolic acid,isocitrate,isovite,quinic acid,etc.