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The effects of varying concentrations of cadmium (Cd) on the development of Lycopersicon esculentum cv. Micro-Tom (MT) plants were investigated after 40 days (vegetative growth) and 95 days (fruit production), corresponding to 20 days and 75 days of exposure to CdCl 2 , respectively. Inhibition of growth was clearly observed in the leaves after 20 days and was greater after 75 days of growth in 1 mM CdCl 2 , whereas the fruits exhibited reduced growth following the exposure to a concentration as low as 0.1 mM CdCl 2 . Cd was shown to accumulate in the roots after 75 days of growth but was mainly translocated to the upper parts of the plants accumulating to high concentrations in the fruits. Lipid peroxidation was more pronounced in the roots even at 0.05 mM CdCl 2 after 75 days, whereas in leaves, there was a major increase after 20 days of exposure to 1 mM CdCl 2 , but the fruit only exhibited a slight significant increase in lipid peroxidation in plants subjected to 1 mM CdCl 2 when compared with the control. Oxidative stress was also investigated by the analysis of four key antioxidant enzymes, which exhibited changes in response to the increasing concentrations of Cd tested. Catalase (EC 1.11.1.6) activity was shown to increase after 75 days of Cd treatment, but the major increases were observed at 0.1 and 0.2 mM CdCl 2 , whereas guaiacol peroxidase (EC 1.11.1.7) did not vary significantly from the control in leaves and roots apart from specific changes at 0.5 and 1 mM CdCl 2 . The other two enzymes tested, glutathione reductase (EC 1.6.4.2) and superoxide dismutase (SOD, EC 1.15.1.1), did not exhibit any significant changes in activity, apart from a slight decrease in SOD activity at concentrations above 0.2 mM CdCl 2 . However, the most striking results were obtained when an extra treatment was used in which a set of plants was subjected to a stepwise increase in CdCl 2 from 0.05 to 1 mM, leading to tolerance of the Cd applied even at the final highest concentration of 1 mM. This apparent adaptation to the toxic effect of Cd was confirmed by biomass values being similar to the control, indicating a tolerance to Cd acquired by the MT plants.

Chromium is a chemical element that occurs in two principal distinct forms: trivalent (Cr(III)) and hexavalent (Cr(VI)). As chromium toxicity depends on its oxidation state, the concentrations of both the species should necessarily be determined, and not only that of total chromium. Using X‐ray spectrometry allied to chemometrics, this work presents a new method for chromium speciation, with no prior separation and/or preconcentration of Cr(III) and Cr(VI) species. Spectra of several solutions containing different concentrations of Cr(III) and Cr(VI) were obtained. The data were treated through principal component analysis and partial least squares regression. The results obtained show that direct speciation using a conventional X‐ray spectrometer is possible, with calculated limits of detection and quantification for Cr(III) and Cr(VI) being lower than 17 and 50 µg g−1, respectively. Copyright © 2010 John Wiley & Sons, Ltd.

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Recebido em 25/8/09; aceito em 13/1/10; publicado na web em 23/4/10 A CLEAN, FAST AND SIMPLE METHOD TO DETERMINE THE ENERGY VALUE OF DRIED FOODS AND BREAKFAST CEREAL. The Energy Value (EV) corresponds to the sum of the energetic contributions from food macronutrients (proteins, carbohydrates and fats) and is required on the labels of pre-packaged foods. The determinations of these parameters are based on distinct analytical procedures, each one being time-consuming, laborious and producing residues. This work presents multivariate models to determine the EV contents of industrialized foods for human consumption by using X-ray fluorescence spectra of samples with known parameters, determined through conventional methods. The proposed method is an alternative to conventional analytical methods and does not require any reagent, given the demands of the "green chemistry". Keywords: energy value; green chemistry; X-ray fluorescence. INTRODUÇÃOA dieta adequada de um adulto, segundo as recomendações internacionais, deve envolver um consumo diário de 2000 kcal. Para que a dieta seja caloricamente balanceada, 45 a 55% deste total devem ser provenientes de carboidratos; 12 a 13% de proteínas; 10% de açúcares e 20 a 30% de gorduras. 1A energia que um alimento fornece ao organismo para que ele possa realizar suas funções biológicas é chamada de valor energético (VE).2 Nos países em que existem legislações sobre a rotulagem dos alimentos, informações sobre VE devem ser apresentadas obrigatoriamente em todos os produtos industrializados. 2,3Através do rótulo, o consumidor adquire dados para escolher os alimentos a fim de balancear sua dieta, evitando excessos e deficiências que possam acarretar problemas de saúde. 4,5 Bryant e Atwater estudaram o comportamento dos alimentos verificando a disponibilidade de seus macronutrientes, ou seja, o quanto é liberado de calor na queima (oxidação) destes nutrientes. 6 Os resultados permitiram constatar que, em média, cada grama de proteína ou de carboidrato libera 4 kcal de energia, enquanto para cada grama de gordura este valor é 9 kcal.6 Desta forma, para obter VE pela relação estabelecida por Bryant e Atwater (Equação 1) é preciso obter as quantidades, em gramas, de carboidrato (C), proteína (P) e gordura (G) presentes em cada grama de amostra (g/g). 7 VE = 4C + 4P + 9G(1)Os valores obtidos por Bryant e Atwater com relação à disponibilidade de seus macronutrientes foram resultados de estudos feitos a partir da ingestão mista (variada) de alimentos e por isso são conhecidos como fatores gerais de Atwater.7 Estudos têm sido feitos para verificar os valores específicos para cada tipo de alimento, constando pequenas variações nos fatores gerais e levando a constantes adaptações da Equação 1. Mesmo assim, a equação, tal como sugerida inicialmente, é aplicada e aceita pelos métodos oficiais atualmente. 7A determinação dos macronutrientes é feita a partir de procedimentos analíticos distintos, o que tende a aumentar os erros envolvidos no cálculo de VE pela equação de Bryant e Atwater, pois ...