TRACE ELEMENTS IN ICE TEA: TOTAL CONTENT AND BIOAVAILABILITY EVALUATION

Tea is one of the most consumed non-alcoholic beverages in world and it is frequently associated to health benefits, such as the prevention of heart diseases. Besides its rich nutritional composition (antioxidants compounds, minerals and vitamins), non-essential trace elements associated with toxic effects may also be present. Nevertheless, it is well known that after eating, the food components undergo biotransformation processes along the gastrointestinal tract. Therefore, the evaluation of trace elements bioavailability is essential for the correct assessment of the nutritional benefits or risk associated with the food intake. In the present work, the total content and the bioavailability of aluminum, copper, manganese and strontium were evaluated in 16 samples of ice tea commercialized in Campinas, SP (Brazil). An in vitro simulation of the gastric (pepsin solution in 1.0 mol L-1 HCl) and intestinal juice (pancreatin and bile salts in 0.1 mol L-1 NH4HCO3) was applied for bioaccessibility evaluation and Caco-2 cells culture was used as an intestinal epithelial model (bioavailability). Trace elements determination was performed using the solution obtained from microwave acid digestion with quantification utilizing an ICP OES instrument (5100 VDV, Agilent Technologies, Tokyo, Japan). It was found that the total trace elements content in ice tea samples ranged from 289 to 3504 µg L-1, <7.9 to 23 µg L-1, 1164 to 6709 µg L-1 and 39.1 to 219 µg L-1 for Al, Cu, Mn and Sr, respectively. In general, bioaccessible fractions of these trace elements in ice tea corresponded to 50% of the total content, being the lowest Cu bioaccessible fractions observed in green ice tea samples (37% to 50%). Besides Mn bioaccessibility and bioavailability fractions presented the same behavior (green ice tea > black ice tea > mate ice tea), Sr bioavailability fractions were 50% higher in green tea than in black tea samples.