Differentiation of tea (Camellia sinensis) varieties and their geographical origin according to their metal content

The metal content of 46 tea samples, including green, black, and instant te as, was analyzed. Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Sr, Ti, and Zn were de termined by ICP-AES. Potassium, with an average content of 15145.4 mg kg(-1 ) was the metal with major content. Calcium, magnesium, and aluminum had av erage contents of 4252.4, 1978.2, and 1074.0 mg kg(-1), respectively. The a verage amount of manganese was 824.8 mg kg(-1). There were no clear differe nces between the metal contents of green and black teas. Pattern recognitio n methods such as principal component analysis (PCA), linear discriminant a nalysis (LDA), and artificial neural networks (ANN), were applied to differ entiate the tea types. LDA and ANN provided the best results in the classif ication of tea varieties. These chemometric procedures were also useful for distinguishing between Asian and African teas and between the geographical origin of different Asian teas.