Studies On Fungal Communities Diversity And Origin Identification Feature Information Of Wuyi Rock Tea

Wuyi rock tea was a semi fermented Oolong Tea,one of the geographical indications protection products in China.In this study,high throughput sequencing technology was used to analyze the fungal population in 29 Wuyi rock tea samples,compared the differences of fungal diversity in Wuyi rock tea samples in different origin.The contents of 6 kinds of catechins and 11 kinds of amino acids in tea samples were determined by HPLC,and analyzed the correlation between the content of these biochemica]components and the abundance of funguses.This study also collected 74 Wuyi rock tea samples and 10 imitation tea samples form Wuyishan and surrounding areas,and stored for a year.During storage,high performance liquid chromatography(HPLC),electronic tongue and near infrared spectroscopy(FTIR)were used to determine the catechins and amino acid contents for 6 times,taste information for 3 times,and the characteristics of the chemical components for 6 times,the principal component analysis(PCA),random forest(RF)and conditional inference tree(CIT)and partial least squares regression(PLSR)were used to analyze the data.During the Wuyi rock tea samples storage,the changes of the chemical characteristics,the stability of the identification model and the contribution of each characteristic variable in the identification of the origin were studied.The results were mainly as follows:(1)The fungal diversity and community structure in 24 Wuyi rock tea samples and 5 imitation tea samples were studied with high-throughput sequencing technology and means of sequencing the rDNA fragments.After the sequencing data optimization,2438480 high quality sequences were obtained,the length of the sequences were mainly between 200?300 bp,can be classified into 873 operational taxonomic units(OTU).612 OTUs were unique in Wuyi rock tea samples,157 OTUs were common in tea samples,and 104 OTUs were unique in imitation tea samples.After the OTU representative sequences comparison,4 phyla,15 classes,44 orders,76 families and 159 genera of fungi taxa were identified,Ascomycota?Eurotiomycetes?Trichocomaceae?Eurotiales?Aspergillus?Aureobasidium were widely distributed in the tea samples.Compared with the imitation tea samples,the diversity of fungi in origin Wuyi rock tea samples was more abundant.Using the relative abundance of fungi as parameters to cluster the tea samples by euclidean distance,the results showed that the relative abundance of fungi was associated to the region and variety of Wuyi rock tea.(2)High performance liquid chromatography(HPLC)was used to determine the content of 6 kinds of catechins and 11 kinds of amino acids in tea samples.The results of correlation analysis showed that the relative abundance of fungus were related to the content of catechins and amino acids in tea samples,and the contents of catechins and amino acids in original tea samples were related to some fungus.(3)74 Wuyi rock tea samples and 10 imitation tea samples were stored for a year,the content of 6 kinds of catechins and 11 kinds of amino acids in tea samples were detected in 6 times by HPLC during storage.The results showed that the contents of catechins and amino acids in tea samples were decreased after storage,the content of tyrosine,phenylalanine,leucine,C(catechin),EC(gallic acid)and ECG(epigallocatechin gallate)were decreased by 20%.The content of catechins were measured as input parameters,the correct recognition rates of random forest(RF)origin classification model were between 83%and 86%in 6 times,the correct recognition rate was 85.53%when all catechins data as input parameters.The content of amino acids were measured as input parameters,the correct recognition rates of random forest(RF)origin classification model were between 76%and 83%in 6 times,the correct recognition rate was 82.24%when all amino acids data as input parameters.The content of tyrosine,phenylalanine,leucine,catechin,epigallocatechin gallate,epigallocatechin gallate were showed higher contribution in RF identification model of Wuyi rock tea origin.(4)The tea samples were taken 3 times of electronic tongue taste information collection during storage,the principal component analysis(PCA)showed that the taste information has been changed.Set the electronic tongue sensor data of tea samples as input parameters,the correct recognition rate of CIT Wuyi rock tea origin identification model was 94.97%.The relative importance of GPS,STS,SRS,SPS sensors data in the identification model of Wuyi rock tea origin was higher than other sensors.(5)The stored tea samples were analyzed by near infrared spectroscopy(NIR)for 6 times in one year,the prediction accuracy of NIR-PLSR model reached 88.53%.The data of 6700-8000cm-1 scanning wavelength range in near infrared spectrum was showed good performance in NIR-PLSR model,the prediction accuracy of reached 91.00%.In short,Wuyi rock tea has obvious origin characteristics.Affected by the tea aging,the identification information in Wuyi rock tea will change after one year storage.But the origin recognition model which based on the feature variables,still effective in origin identification of Wuyi Rock Tea.