Monitoring of essential and heavy metals in green tea from different geographical origins

Abstract

The present study measured the concentrations of toxic metals (Cd, Pb) and other elements (Ca, K, Mg, Na, P, Mn, Fe, Zn, Cu, Co, Cr, Ni) in tea leaves and their infusions. The total metal contents were determined by atomic absorption spectrometry. Phosphorus concentration was determined using an ultraviolet–visible spectrophotometer. Assessment of the mineral composition enabled determination of the leaching percentage and the risk of exceeding provisional tolerable weekly intake for Cd through daily tea consumption. The concentrations of bioelements were analyzed based on the recommended daily intake values for each. According to recently established standards, green tea was found to be a rich source of Mn. The average Pb and Cd levels in a 200-mL beverage were 0.002 and 0.003 mg, respectively. Indian teas had the highest percentage of Cd leaching (43.8 %) and Chinese tea had the lowest (9.41 %). Multivariate analysis techniques such as factor analysis and cluster analysis were used to differentiate samples according to geographical origin (China, India, or Japan). Potassium, P, Mn, Fe, Cu, Co, and Cd were effective descriptors for the identification of tea samples from China, India, and Japan.

Dietary Content and Potential Health Risks of Metals in Commercial Black Tea in Kampala (Uganda)

“…Levels of potassium were higher in locally manufactured branded tea, than in non-branded and imported branded tea. The observed concentrations of potassium are a result of specific incorporation of potassium within a binding ligand of the tea leaves (Brzezicha-Cirocka, Grembecka, & Szefer, 2016). The studied black teas showed high potassium contents in agreement with previous researches (Table 3).…”

“…Toxic metal concentrations in teas were below WHO and USFDA limits ( Table 1). Levels of metals in tea plants depend on age of the tea leaves, soil conditions, rainfall, altitude, and genetics (Jamshidpour, faramarzi, Mahmoudi, & Varmira, 2016;Brzezicha-Cirocka et al, 2016). The amount of HM in tea leaves may be interpreted as an indicator for contamination of the environment by heavy metals (Gebretsadik & Chandravanshi, 2010).…”

Evaluation of Macro- and Microelement Levels in Black Tea in View of Its Geographical Origin

“…The bulk teas were homogenized and representative samples were mineralized in an electric furnace and then analyzed by flame atomic absorption spectrometry (FAAS) according to the previously published procedure by Brzezicha-Cirocka et al [19, 20]. …”

“…These techniques have been applied to elemental and organic composition data, obtained using various analytical techniques including HPLC [6–8], GC-MS [9–11], 1 HNMR [12], FT-NIRS [13], ICP-MS [5, 14–16], and FAAS [17–20]. Our previous studies have showed that FA and CA are efficient tools of green, fruit, and Pu-erh tea diversification [19, 20]. These two multivariate techniques applied to green tea data enabled differentiation of samples according to their provenance [19].…”

“…Our previous studies have showed that FA and CA are efficient tools of green, fruit, and Pu-erh tea diversification [19, 20]. These two multivariate techniques applied to green tea data enabled differentiation of samples according to their provenance [19]. Moreover, it was also possible to diversify Pu-erh tea according to its type of confection, whereas fruit teas were differentiated according to their type [20].…”