The season when tea is harvested, as well as the age of the tea can affect its quality, hence authenticating the season/age of high cost teas can be desirable. Chinese researchers have used trace elements and stable isotopes with chemometrics to characterise Pu'er tea according to its production year. Pu'er tea is prepared by drying green Chinese tea, then subjecting it to a microbiological fermentation by naturally occurring moulds, bacteria and yeasts. The tea is then pressed into a variety of shapes.
A total of 86 mineral elements and stable isotope compositions were determined from the Xiangzhujing Pu'er tea in five different production years. Different chemometric techniques were applied to find the best models to predict the production year. Mn,68Zn, and 203Tl were the best authenticity markers for enabling the successful authentication of Pu'er tea with different production years.
Read the abstract here