Bioacessibilidade in vitro de espécies metálicas em chá de camomila e chá- mate: avaliação de metodologias e uso dos dispositivos de difusão em filmes finos por gradiente de concentração (DGT)

Abstract

Food and drinks, contribute to the supply of specific components that are extremely important in cellular metabolism, such as metallic species. Therefore, studying the presence and biological availability of these species in foods and beverages such as teas becomes very important to ensure food safety. In this context, the present study aims to evaluate the in vitro bioaccessibility of metallic species in commercial samples of chamomile tea and mate tea and in prepared infusions, using two different methodologies: the physiologically based extraction - PBET and the unified bioaccessibility method - UBM, and the Diffusive Gradients in Thin-films technique (DGT) to simulate absorption by the cell membrane. Chromium determinations were performed by FAAS and GF AAS. Total chromium concentrations in mate tea ranged from 0.124 to 0.352 μg L-1 among brands, and for chamomile the concentration was 0.62±0.11 μg g-1

. Bioaccessible percentages of Cr in mate tea were 39±9% with the UBM method and 83±15% with PBET. For both teas, there was a significant difference in bioaccessible percentages between the methods evaluated (p<0.05). When applying the methods (PBET and UBM) to mate tea infusions, bioaccessible percentages of chromium ranged from 43±5% to 66±7% in the PBET method and from 64±3% to 115±22% in UBM, according to the masses used. For chamomile infusions, the bioaccessible percentages ranged from 19±2.4% to 28±22% for the PBET method and from 59±26% to 74±32% for the UBM method. To apply the DGT device technique, only the UBM method and the mate tea samples, and their infusions were used. To evaluate the performance of the homemade DGT devices, studies to determine the diffusion coefficient of chromium in the agarose hydrogel and the elution factor were performed. With these data, the homemade DGT devices can be applied in aqueous solutions of Cr3+ and the recovery was 88±2%. The DGT devices were then implanted in the gastrointestinal fluids obtained after applying the UBM test to the mate tea and its infusions. The labile Cr(III) concentrations in the bioaccessible fractions of mate tea ranged from 0.06±0.01 μg g-1

to 0.079±0.002 μg g-1

. In the bioaccessible fractions of the infusions, only brand A quantified labile Cr(III), with a concentration of 0.058±0.014 μg g-1 . In an unprecedented study, the direct use of homemade DGT devices in mate tea infusions was also proposed. For sample A, the labile Cr(III) concentration in the infusion was 0.0585±0.004 μg g-1

, that is, practically the same as that determined by

the DGT devices, 0.06±0.01 μg g-1

. In this case, using the DGT technique, which is simpler when compared to bioaccessibility tests, statistically equal results were obtained. For samples B and C, the amount of labile Cr(III) found after application of the devices was 0.01±0.001 μg g-1 and 0.005±0.001 μg g-1

, respectively. The trivalent

chromium content in these infusions did not reach 10%.