| As a berry fruit,mulberry is rich in nutrients,has a variety of functions such as anticancer and antioxidant,and is deeply loved by consumers.At present,in the analysis of fruit,there are few studies on mulberry metabolites,and there is a lack of high-throughput analysis methods,especially in terms of quality formation and variety breeding.Therefore,in this thesis,a quasi-targeted metabolomics method was established for the quality analysis of different varieties and different growth periods of mulberry samples,and the results of the study were as follows:1.Establish a method for quasi-targeted metabolomics semi-quantitative analysis of metabolites based on liquid phase mass spectrometry platform.First of all,the mass spectrometry scanning of mulberry samples is carried out by the LC-QTOF/MS full sweep method to obtain the information of all small molecule metabolite mother ions and daughter ions of the mulberry sample,and then the LC-QQQ/MS is used to detect the sample for secondary detection,and the detection method is based on the ion information obtained by the full sweep,and the sample is detected by quasi-targeted metabolomics method.Finally,251 kinds of metabolites were obtained,including amino acids(31 kinds),organic acids(22kinds),phenolic acids(21 kinds),flavonoids(45 kinds),sugar alcohols(16 kinds),lipids(10kinds),alkaloids(9 kinds),nucleosides(31 kinds),amines(8 kinds),etc.,and the verification methods mainly included linearity,accuracy and stability.The results show that the gradient of different concentrations shows a good linear relationship with the peak height,and the relative standard deviation(RSD)obtained by the sample during repeated injection is also appropriate,indicating that the method is feasible.2.Based on quasi-targeted metabolomics,the quality differences of different varieties of mulberry were studied.The test determined mulberry varieties included purple mulberry((Indian mulberry,Japanese 4 ploid mulberry,Dashi,Zhong shen No.1),white mulberry(Bai Sang No.4,Bai Yuwang,Xiao Baie)and red mulberry(Jane 4).The experimental results show that there are obvious differences between the quality indexes and small molecular metabolites of different varieties of mulberry extracts.Among them,the total phenol content and antioxidant activity were in order of purple mulberry> red mulberry >white mulberry,while the total sugar content was the opposite;the protein content was the highest in the purple mulberry in Indian mulberry and medium mulberry No.1.The metabolites of different varieties of mulberry were analyzed by quasi-targeted metabolomics technology,and the content of flavonoids and phenolic acids was higher than that of purple,red and white mulberries,which may be the main reason for the high total phenol and antioxidant activity;compared with white mulberry,the amino acid content of white mulberry was higher;compared with red mulberry,the sugar content in white mulberry was higher.Correlation analysis found that the total sugar in the mulberry phenotype index was positively correlated with 25 metabolites and 46 metabolites,proteins were positively correlated with 34 metabolites and 16 metabolites,and total phenols and antioxidant activities were positively correlated with most phenolic acids and flavonoids,such as neochloroic acid,parahydroxybenzoic acid,ferulic acid,genistein,rutin,hypericin,etc.Among them,the total phenol was positively correlated with 61 metabolites and negatively correlated with 45 metabolites,and the antioxidant activity was positively correlated with 68 metabolites and negatively correlated with 12 metabolites.3.Based on metabolomics,the quality detection and difference analysis of mulberry metabolites in different growth periods were studied.The materials selected are purple(Da Shi),white(Bai Yuwang)and red(Hong Guo72C001)mulberry.The experimental results showed that there were significant differences in the quality index and small molecular metabolites of mulberries in different growth periods.The protein content of mulberries decreased with the maturity of mulberries at different growth stages,and the total sugar content increased;the total phenol content and antioxidant activity of purple mulberries increased with the growth of mulberries,white mulberries decreased with mulberry maturity,and red mulberry had no obvious change.Using pseudo-targeted metabolomics technology to analyze different growth periods,it was found that amino acids and sugar alcohols in different varieties of mulberries gradually accumulated with the growth period of mulberries;flavonoids and phenolic acids in white and purple mulberries increased with the growth period.In addition,the organic acids such as maleic acid,malic acid,quinic acid,and pantothenic acid decreased continuously during the development of mulberry. |
