Quantification, identification and comparison of oligopeptides on five tea categories with different fermentation degree by Kjeldahl method and ultra-high performance liquid chromatography coupled with quadrupole-orbitrap ultra-high resolution mass spectrometry

• Published in: Food chemistry 2022-06, Vol.378, p.132130-132130, Article 132130
• Main Authors: Zhao, Feng, Qian, Jiang, Liu, Hui, Wang, Chi, Wang, Xiaojuan, Wu, Wenxi, Wang, Danhong, Cai, Chunping, Lin, Yu
• Format: Article
• Language: English
• Subjects: Bio-function; Chromatography, High Pressure Liquid; Fermentation; Fermentation degree; Kjeldahl method; Mass Spectrometry; Oligopeptide; Oligopeptides; Peptide patterns; Tasted; Tea; UHPLC-Quadrupole-Orbitrap-UHRMS
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2022.132130

•An oligopeptide quantification method for tea was developed.•Oligopeptide amounts and patterns of five tea categories were compared.•Withering and post-fermentation were key for oligopeptide enrichment.•A total of 902 abundant peptides were identified.•Certain oligopeptides with biological or taste activities were screened out. Peptides with different lengths or amino sequences could have specific tastes or bio-activities. So far, either the quantity or pattern differences of peptide among various of teas were unknown. Here, firstly, we developed a method for tea oligopeptide quantification and made comparison of their contents. Secondly, we applied ultra-high performance liquid chromatography coupled with quadrupole-orbitrap ultra-high resolution mass spectrometry (UHPLC-Quadrupole-Orbitrap-UHRMS) to sequence oligopeptides. As a result, the total amount of oligopeptides in white tea and dark tea were higher, followed by black tea and green tea, finally with oolong tea. It suggested that withering which undergoes with endogenous protease and post-fermented that undergoes with a participation of exotic micro-organisms were key in oligopeptide enrichment. Thirdly, a total of 902 abundant identified peptides, most of which were tripeptide, tetrapeptide, pentapeptide, and hexapeptide were screened against several existing peptide databases. There were a series of taste peptides and bio-active peptides existing.