Food Science and Technology (Campinas)
versão On-line ISSN 1678-457X
ANDRADE, Édira Castello Branco de; TEODORO, Anderson Junger e TAKASE, Iracema. Determination of zinc in different extracts in samples of A and B vegetables. Ciênc. Tecnol. Aliment. [online]. 2005, vol.25, n.2, pp. 265-270. ISSN 1678-457X. http://dx.doi.org/10.1590/S0101-20612005000200014.
Zinc which is an essential microelement or a trace-element, part in essential humans functions. Physicochemical interactions among nutrients include: adsorption, complex synthesis and precipitation which consequently have an influence in the bioavailability. It isn't possible to measure how much of the metal is absorbed, even if one knows its total intake. However, through metal's speciation technique, which is defined as the determination of the concentration of different physicochemical forms of the elements that together represent the total amount of this in the sample, we can have new data to foresee metal's absorption. Solid samples require a selective or sequential extraction method to assess metals' speciation. In that way, total contents of zinc were analysed in samples of A and B vegetables through atomic flame the absorption spectroscopy and sequential extraction made by the following extractors: CaCl2 1M solution; Acetic acid 0.1M solution; Acetic acid solution 0.5M/Ammonium acetate 5% [pH=5.0]; NaOH 0.1M solution and HCl 0.5M solution. Grubbs test was used to reject results. For 8 samples, the amount of zinc extracted was complete, 6 samples showed at least 75%, 5 samples extracted 50%, a sample of okra extracted 27% and a sample of beet only 3% . For the majority of samples, zinc was found in at least six different chemical species. Future studies which may identify these species will surely help to evaluate the bioavailability of this metal.
Palavras-chave : zinc; sequential extraction; bioavailability.