Edible mushroom species: mineral profile, bioaccumulation of metals and preparation of certified reference material

No presente estudo foram determinadas as concentrações de vinte e cinco elementos (Al, As, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Sn, Sr, V e Zn) em três espécies comestíveis de cogumelos, Lentinula edodes (Shiitake), Pleurotus ostreatus (Shimeji) e Pleurotus eryngii (Cardoncello) coletadas no Cultivo Cogumelos Imperial, Petrópolis, Rio de Janeiro. As amostras foram coletadas trimestralmente durante o ano de 2010. Um grama de amostra foi seco em estufa, homogeneizado em processador doméstico e pesado em cadinho de porcelana. Após a pré-digestão com adição ácido nítrico concentrado procedeu-se à mineralização em forno mufla na temperatura de 450º C por 12 h. As cinzas foram solubilizadas com 2 mL de ácido nítrico 10 % (v/v) e o conteúdo transferido com água desionizada para frasco de polipropileno de 15 mL. Utilizou-se para a determinação dos elementos as técnicas analíticas ICP-MS, utilizando Rh como padrão interno e EAA chama. Dois materiais de referência certificados do National Institute of Standards and Technology (NIST), Apple Leaves n° 1515 e Mussel Tissue n° 2976 foram utilizados obtendo valores de recuperação em torno de 98 %, com exceção para o Sn (51 %). Os resultados demonstraram que os cogumelos estudados são alimentos com altos teores de Fe, Mg, Mn, Mo e Zn com mais de 30 % das quantidades recomendadas para ingestões diárias para estes nutrientes conforme a RDC nº 269 e a portaria nº 27. Os cogumelos também apresentaram uma razão muito baixa Na/K, caracterizando-os como alimentos recomendados para hipertensos e as concentrações de Cd, Pb e As estão abaixo dos limites máximos permitidos preconizados pela legislação em vigor...In this study we determined the concentration of twenty-five elements (Al, As, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb , Sb, Se, Sn, Sr, V and Zn) in three species of edible mushrooms, Lentinula edodes (shiitake), Pleurotus ostreatus (Shimeji) and Pleurotus eryngii (Cardoncello) from Petropolis, Rio de Janeiro. Samples were collected quarterly during the year 2010. One gram of sample was oven-dried, homogenized in domestic processor and after a pre-digestion with concentrated nitric acid addition proceeded to mineralization in a muffle furnace at a temperature of 450 ° C for 12 h. The ashes were solubilized with 2 ml of nitric acid 10 % (v/v) and transferred with deionized water to a polypropylene 15 mL bottle. For the elements determination it was used ICP-MS, using Rh as internal standard and FAAS. Two certified reference materials from NIST, Apple Leaves nº 1515 and Mussel Tissue nº 2976, obtained recovery values around 98 %, except for the Sn (51 %). The results showed that the mushrooms are foods with high levels of Fe, Mg, Mn, Mo and Zn over 30% from the recommended daily intake for these nutrients according to Brazilian Legislation. The mushrooms also showed a very low ratio Na/K, characterizing them as recommended foods for hypertensive and their concentrations of Cd, Pb and As are below the recommended maximum limits allowed by Brazilian legislation. Two mushrooms, Shiitake and Cardoncello, as candidates of certified reference material was prepared and a collaborative study took place with ten laboratories. Nine elements, Ca, Cd, Cu, Fe, K, Mg, Mn, Na and Zn, had their concentrations certified. In bioaccumulation studies, factors were determined for 14 elements Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Rb, Sr, V and the results showed thate Al, Ca, Mn, Sr are bioexcluded elements. It was concluded that among the morphological structures, cap and stem, the elements are in greater quantity in the cap