Curie-point pyrolysis–gas chromatography–mass spectroscopic analysis of theabrownins from fermented Zijuan tea

Zijuan tea theabrownins (ZTTBs) was extracted from a type of fermented Zijuan tea and separated into fractions according to molecular weight. The extract was found to contain predominantly two fractions: <3.5 kDa and >100 kDa. These two fractions were analyzed for chemical composition, structural characteristics by Curie-point pyrolysis–gas chromatography–mass spectroscopy (CP-Py–GC/MS). The affects of pyrolysis temperature on pyrolytic products were also investigated. The fraction >100 kDa produced 50 GC/MS peaks during pyrolysis at 280 °C, 70 peaks at 386 °C, and 134 peaks at 485 °C. Fourteen of the products formed at 280 °C, 12 of those formed at 386 °C, and 21 of those formed at 485 °C were identified with match qualities of greater than 80%. The fraction <3.5 kDa gave 51 peaks during pyrolysis at 280 °C, 99 peaks at 386 °C, and 257 peaks at 485 °C. Six products formed at 280 °C, four products formed at 386 °C, and 61 products formed at 485 °C were identified with match qualities of greater than 80%. Pyrolysis temperatures of 485 °C and 386 °C were found suitable for the two fractions respectively. CP-Py–GC/MS revealed that, the fraction >100 kDa mainly consisted of phenolic pigments, esters, proteins, and polysaccharides, while the fraction <3.5 kDa contained no polysaccharide. CP-Py–GC/MS is an effective tool for the composition difference and structural characteristics of ZTTBs as well as other complex macromolecular plant pigments.