The efficiency of cysteine to remove mercury from sliced and minced shark was evaluated. Treatment with 0.5% cysteine at pH 2.0–2.5 and subsequent washing with sodium chloride (5%) failed to remove the mercury from the sliced shark. The efficiency of 0.5% cysteine at pH 7.0 in removing mercury from minced shark was 40–45% (dry material), obtained by two of the three methods studied. This removal rate was considered relatively low for it failed to attend to the practical proposal of decontaminating species of fish highly contaminated by mercury. The need for fuller understanding of the mechanisms involved in the removal of mercury by cysteine was also considered.
INTRODUÇÃO: Localizada em Caçapava, SP, Brasil, indústria produtora de lingotes de chumbo provocou contaminação ambiental na região do Vale do Paraíba, com chumbo e cádmio. Com o objetivo de avaliar o grau de contaminação do leite produzido na região, devido à possível ingestão, pelo gado, de gramíneas e águas contaminadas, foram determinados os teores de chumbo e cádmio no leite. MATERIAL E MÉTODO: Foram analisadas 218 amostras de leite in natura e pasteurizado. O cádmio e o chumbo foram determinados por espectrofotometria de absorção atômica com chama. RESULTADOS E CONCLUSÕES: Das amostras analisadas, 43 apresentaram teores de chumbo acima do limite máximo estabelecido pela legislação brasileira que é 0,05 mg/kg. O valor da mediana encontrada para o chumbo foi 0,04 mg/L. Os níveis de cádmio em todas as amostras foram menores que o limite de quantificação do método que é 0,02 mg/L. Apesar da contaminação ambiental, os níveis encontrados para o cádmio no leite estão abaixo do limite estabelecido pela legislação brasileira que é 1,0 mg/kg.
Recebido em 4/1/09; aceito em 19/7/09; publicado na web em 25/11/09 Different methods to determine total fat (TF) and fatty acids (FA), including trans fatty acids (TFA), in diverse foodstuffs were evaluated, incorporating gravimetric methods and gas chromatography with flame ionization detector (GC/FID), in accordance with a modified AOAC 996.06 method. Concentrations of TF and FA obtained through these different procedures diverged (p< 0.05) and TFA concentrations varied beyond 20 % of the reference values. The modified AOAC 996.06 method satisfied both accuracy and precision, was fast and employed small amounts of low toxicity solvents. Therefore, the results showed that this methodology is viable to be adopted in Brazil for nutritional labeling purposes.Keywords: total fat; fatty acids; nutritional labeling. INTRODUCTIONNutritional labeling information is one of the employed strategies by the World Health Organization to avoid chronic disease.1,2 Since inadequate ingestion of both saturated and trans fatty acids increases cardiovascular diseases risk, 3 the attention to dietary fat has increased either in health aspects and in analytical determination. Brazilian legislation demands the declaration of total fat (TF), saturated (SFA) and trans fatty acid (TFA), among other nutrients, on the label of packed foods (RDC 360/03 ANVISA/MS). 4 To commit to such legislation, laboratories must be able to verify, by means of analysis, the contents declared on labels. 5Total fat and fatty acid determination in food products comprises several steps and, depending on the type of food, laws and analysis procedures, different results should be generated. 6,7 Food lipids are constituted mainly, more than 90%, by triacylglycerol (TAG), which are esters of fatty acids and glycerol. Phospho-and glycolipids, sterols, waxes and free fatty acids are minor components of food fat. When not free, fatty acids are linked in such compounds by ester or amide bonds to other molecules but glycerol. 8 Total fat determination requires a quantitative extraction of all lipid compound classes and the breakage of bonds and interactions with nonfat compounds. As various energy amounts are involved (interactions range from van der Waals to ionic forces), appropriate solvents should be chosen for each case. The fat content of food has traditionally been determined by extraction with organic solvents, followed by extract drying and gravimetric determination. Non-polar organic solvents such as chloroform and n-hexane are used for disrupting hydrophobic and ion-dipole interactions (e.g. lipid hydrophobic chain and non-polar amino acids) whereas polar organic solvents with high dielectric constant, such as methanol, for breaking hydrogen bonds (e.g. non-lipid compounds and lipid hydroxyl, carboxyl or amino groups). [6][7][8] Several methods have been reported in the literature and are indicated for specific food matrices. Fat extraction based on Soxhlet method (reflux with diethyl ether, petroleum ether or n-hexane) extracts neutral lipid, such as t...
IntroduçãoDe acordo com a RDC 360/2003 da ANVISA -Agência Nacional de Vigilância Sanitária, é obrigatória a declaração dos níveis de ácidos graxos trans na rotulagem dos alimentos embalados no Brasil (MINISTÉRIO DA SAÚDE, 2003a). As informações nutricionais, na rotulagem dos alimentos, contribuem para a escolha de dietas mais saudáveis. A ingestão inadequada de ácidos graxos trans pode aumentar o risco das doenças cardiovasculares, as quais são a principal causa de morte no mundo (MOZAFFARIAN et al., 2006;HAWKE, 2004; OMS, 2003).Cerca de 80% dos ácidos graxos trans da dieta provêm das gorduras parcialmente hidrogenadas, obtidas em processo industrial de hidrogenação de óleos vegetais insaturados, como óleo de soja. Na hidrogenação, os isômeros predominantes são monoenoicos cis e trans formados pela migração e isomerização das duplas ligações. Entretanto, os ácidos graxos trans podem ocorrer naturalmente, em pequenas quantidades, na gordura de animais ruminantes (leite e carne), sendo formados pelo processo de biohidrogenação no rúmen dos animais, por ação de enzimas bacterianas (MARTIN et al., 2007; MAZOFFARIAN et al., 2006).Os óleos vegetais polinsaturados de sementes como de soja, milho e canola representam uma fração importante da dieta humana e, nos últimos anos, o consumo destes óleos tem aumentado enquanto que o das gorduras de origem animal diminuiu. Ácidos graxos trans também se formam, em AbstractThis paper describes the results of fatty acids composition, mainly trans, in refined polyunsaturated vegetable oils, commercialized in the city of São Paulo, Brazil during the years 2005 and 2007. The following samples were analyzed: 34 of soybean oil, 7 of sunflower oil, 2 of canola, and 6 of corn oil. The fatty acids were transesterified in a cold process and analyzed with optimized conditions by gas chromatography in a 100 m capillary column (SP 2560). Sixteen samples of soybean, two of canola, and four of sunflower oil showed levels of trans fatty acids higher than 2.0% (w/w methyl ester). In accordance with RDC 360/2003 of the Brazilian Sanitary Survey Agency (ANVISA), the trans fatty acid content must be on the nutrition facts label all food labels. Samples with less than 0.2 g of trans fatty acids per serving are considered free of them. The serving for vegetable oil is 13 mL. Therefore, the label of several vegetable oil samples analyzed should contain levels of trans fatty acids higher than zero. The vegetable oil refining process improvement, like the controlling of deodorization temperature, could contribute to meet the recommendations of the World Health Organization to minimize the trans fatty acids levels in food and to preserve the population health.
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