Effects of geographical origin, variety, season and their interactions on minerals in tea for traceability

In order to find formation causes of mineral fingerprints and their stability among different seasons for tea traceability, tea leaves were studied for the combined effects of geographical origin, variety, harvest season and their interactions on mineral contents. Fresh tea leaves of three varieties from three different regions were analyzed and compared during three harvest seasons. The contents of 16 minerals were determined in 81 tea leaf samples. The contributions of geographical origin, variety, season and their interactions to the content variability of each element were calculated by multi-way analysis of variance. The results showed that grown origin, variety, harvest season and their interactions had significant effects on mineral contents in tea leaves. The contents of Mg, Ni, Rb, Sr, Cd, Cs, Ba and Pb in tea leaves mainly depended on geographical origin; those of Al, Cu and U were closely related to variety; while Na, V, As, Se and Sn were mainly influenced by season. The application of stepwise linear discriminant analysis permitted 100% correct classification of the samples based on Mg, Ni, Rb, Sr, Cd and Pb, which were closely related to geographical origin and less affected by variety and harvest season.