Determination of aluminum and zinc in infusion tea cultivated in north of Iran

Estimated daily intake of epichlorohydrin and certain heavy metals of bagged and loose black teas

This study aimed to determine the levels of epichlorohydrin (ECH) and some metals in 3 brands of bagged and loose black teas which are widely marketed in Alexandria markets, Egypt, and estimate the acceptable daily intake as a safety indicator. Gas chromatography-mass spectrometry results revealed that ECH levels significantly differed between the tested brands steeped for 2 min and tea bags contained higher levels than in loose teas and the levels increased by increasing the steep time. These levels of ECH in all the tested brands either in tea bags or loose teas were higher than the guideline value of 0.10 μg/L. Also, the results illustrated that the adding of sucrose or washing of bags with deionized water for 1 min significantly decreased the levels of ECH. In addition, inductively coupled plasma optic emission spectrometry (ICP-OES) results illustrated that the levels of Al, Pb, and Cd were too low in infusions compared to the established guidelines. Because of the high consumption of tea in Alexanria city, Egypt, it is necessary to determine the contribution of tea to the daily dietary intake of ECH, Al, Pb and Cd. In case of the bagged teas, the calculated daily intake of ECH was on average about 55.37 times greater than that in loose teas. The consumption of both bagged and loose teas infusion could not pose a risk for population as the health hazard index was < 1. It can be concluded that consumers who prefer to use tea bags should rinse these bags before preparing the tea brewer, and do not increase the steeping time to more than 2 min.

Metal concentrations in traditional and herbal teas and their potential risks to human health

Food and beverage consumption is an important route for human exposure to metals. Traditional tea (Camellia sinensis) is a widely-consumed beverage, which may contain toxic metals. This study determined total and infusion concentrations of 5 metals including Al, As, Cd, Cr, and Pb in 47 traditional and herbal teas from 13 countries and assessed their potential risks to human health. The data showed that herbal teas exhibited higher As (0.26mgkg^-1), Cd (0.19mgkg^-1) and Pb (2.32mgkg^-1) than traditional teas. Black tea from India had high Cr at 31mgkg^-1 while white tea from China had low Cr at 0.39mgkg^-1. Arsenic, Cd and Pb did not exceed the WHO limit for medicinal plants excluding one herbal tea with 1.1mgkg^-1 As and 26.4mgkg^-1 Pb. However, Cr in 47% herbal teas and 73% traditional teas exceeded the Canada limit of 2mgkg^-1. Metal concentrations in tea infusions were below the MCL for drinking water except for Al. Total Al and its infusion was lower in herbal teas (47-1745mgkg^-1 and 0.09-3.95mgL^-1) than traditional teas (50.3-2517mgkg^-1 and 0.02-7.51mgL^-1), with 0.9-22% and 4-49% of the Al being soluble in infusion. The Al concentrations in infusion in all black tea and 83, 75 and 25% of the green, oolong and herbal teas exceeded the secondary MCL for drinking water at 0.2mgL^-1. However, the weekly intake of Al from drinking tea (0.001-0.39 and 0.003-0.56mgkg^-1 for children and adults) was lower than the provisional tolerable weekly intake for Al at 1.0mgkg^-1. Our data showed that it is important to consider metal intake from tea consumptions, especially for Cr and Al in heavy tea drinkers.

Multivariate data reduction and discrimination of black and green teas due to the physical fractionation pattern of selected metals determined in their infusions

An analytical scheme for the physical fractionation of Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sr and Zn in black and green teas infusions was proposed. It was based on the ultrafiltration/centrifugation through five membranes having molecular weight cut-offs of 100, 50, 30, 10 and 5kDa. The concentrations of the studied metals in the highest and the lowest molecular weight fractions were found to classify and discriminate the analyzed teas infusions much better than the total metals concentrations. The differences in the physical fractionation patterns of these metals assessed for both tea varieties was profound and let to simply classify the infusions of different black and green teas by principal component analysis and linear discriminant analysis.