Influence of different fermentation raw materials on pyrolyzates of Pu-erh tea theabrownin by Curie-point pyrolysis-gas chromatography-mass spectroscopy.

ABSTRACT

SCOPE In this study, Pu-erh tea was prepared by solid-state fermentation of the sun-dried green tea, short-fermentation black tea, and black tea. Ultraviolet-visible spectroscopy, infrared spectroscopy and Curie-point pyrolysis-gas chromatography-mass spectroscopy (CP-Py-GC/MS) were used to study the characteristics and chemical compositions of the TB formed in these Pu-erh teas. METHODS AND RESULTS: The pyrolysates of the Pu-erh teas' theabrownin (TB1, TB2, TB3) were analyzed at 386°C using a Curie point pyrolysis instrument. TB1, TB2, and TB3 produced 158, 135 and 148 pyrolysis products, respectively. These compounds could be grouped as follows alkaloids, 25.23% (TB1), 25.67% (TB2), and 21.91% (TB3); phenols, 24.19% (TB1), 23.08% (TB2), and 29.91% (TB3); nitrogen-compounds, 11.79% (TB1), 11.25% (TB2), and 13.39% (TB3); hydrocarbons, 10.96% (TB1), 10.37% (TB2), and 11.37% (TB3); ketones, 10.34% (TB1), 6.58% (TB2), and 8.22% (TB3); furan, 5.40% (TB1), 4.06% (TB2), and 2.33% (TB3); alcohol, 3.30% (TB1), 4.16% (TB2), and 3.34% (TB3); fatty acids, 2.80% (TB1), 4.03% (TB2), and 1.42% (TB3); esters 2.17% (TB1), 0.99% (TB2) and 2.35% (TB3); and amines 1.61% (TB1), 2.81% (TB2), and 0.86% (TB3). CONCLUSION: Theabrownin mainly contains alkaloids (caffeine), tea pigments, polysaccharides, proteins and lipids. Its precursors include various polyphenols, tea pigments, alkaloids, polysaccharides, proteins and lipids. These compounds in the raw materials impact the chemical composition of theabrownin, and black tea is not a suitable raw fermentation material for Pu-erh tea.