Flavor composition changes in leaves before and after processing of Broussonetia papyrifera

【Objective】To elucidate the flavor substance changes of Broussonetia papyrifera fresh leaves before and after processed by tea making technology,the free amino acids,fatty acids and volatile components were determined and evaluated. It provided reference for the processing and utilization of the fresh B. papyrifera leaves.【Method】The content free amino acids and fatty acids wereanalyzed by the method of national standard in fresh leaves and leaf products of B. papyrifera.Then,the changes of volatile components was used gas chromatography-ion mobility spectroscopy(GC-IMS)to analyze.【Result】After processed,the free amino acids content was reduced by 39.39% and glycine(Gly)and methionine(Met)were disappeared,asparagic acid(Asp)and glutamic acid(Glu)increased by 5.55 and 3.32 times,respectively.The content of sweet amino acid and bitter amino acid decreased by 78.70% and 82.88% respectively. Unsaturated fatty acids were decreased,butthe types and contents of saturated fatty acids increased,especiallythe content of C11:0 increased by 7.16 times and two kinds of saturated fatty acids C17:0 and C20:0 were newly increased. GC-IMS analysis showed total 60 volatile components were detected in fresh leaves,42 of which were known,accounting for 82.82%. The total of58 volatile components were detected in leaf products,and 39 known components accounting for 81.05%. The aldehydes,alcohols and terpenes would be significantly reduced while ketones,esters and organic acids would be produced in large quantities. In particular,(E,E)-2,4-hexadienal,caproic acid,2-methyl-1-pentanol,2-methyl-1-butanol,cyclohexanone,2-methyl-ethyl butyrate and other ingredients not found in the freshleaves were added. In addition,volatile components that could not be identified by GC-IMS database were significantly increased in the leaf products of B. pyrifera.【Conclusion】Free amino acid and fatty acid in B. pyrifera leaves decrease after processing. The aldehydes,alcohols and terpenes with fresh fragrant and floral smellare significantly decreased,while the ketones,esters and organic acids with fruit and acidity smell are increased. It can guide the processing technology of leaves and the evaluation of aroma quality of products according to the changes of volatile components.