DAN - Artigos em revistas internacionais
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- Vitamin content of fish and fish products consumed in PortugalPublication . Dias, M. Graça; Sánchez, M V; Bártolo, H; Oliveira, LuísaPortuguese Food Composition Table only includes values for vitamins A, B1, B2, PP determined before 1963. Most fish and fish products consumed in Portugal are not included in international food composition tables. Aims: To study vitamin content of fish and fish products consumed in Portugal. Design: Vitamins A, E, D, B1, B2, B6, B12, PP and Folate content was determined in fifty-six samples of raw and cooked fish and fish products, collected between October 1999 and February 2002. A total of thirty-four species (thirty fish and four molluscs) were analysed raw. Twelve fish species and two molluscs were also analysed cooked at least by one cooking method in a total of twentytwo cooked samples. Vitamins A, E, D, B1, B2, B6, PP contents were determined by HPLC methods. Folates and B12 contents were determined by microbiological methods. Results: Vitamin profiles differed significantly between species. Variability in vitamin content was observed and was wider for lipossoluble vitamins. Excluding values under the Limit of Detection, the results varied over a factor of 100 for vitamins A, E, D, a factor of 20 for B6, B12 and niacin and a factor of 15 for B1 and B2. Folate showed the lower variability (factor < 5). Conclusion: The wide variability of vitamin content between species observed strengthens the importance of producing data derived from a selection of species representative of the national food habits.
- Lack of detectable allergenicity of transgenic maize and soya samplesPublication . Batista, Rita; Nunes, Baltazar; Carmo, Manuela; Cardoso, Carlos; Helena, São José; Almeida, António Bugalho de; Manique, Alda; Bento, Leonor; Ricardo, Cândido Pinto; Oliveira, Maria MargaridaBackground: The safety issues regarding foods derived from genetically modified (GM) plants are central to their acceptance into the food supply. The potential allergenicity of proteins newly introduced in GM foods is a major safety concern. Objective: We sought to monitor, in potentially sensitive human populations, the allergenicity effects of 5 GM materials obtained from sources with no allergenic potential and already under commercialization in the European Union. Methods: We have performed skin prick tests with protein extracts prepared from transgenic maize (MON810, Bt11, T25, Bt176) and soya (Roundup Ready) samples and from nontransgenic control samples in 2 sensitive groups: children with food and inhalant allergy and individuals with asthmarhinitis. We have also tested IgE immunoblot reactivity of sera from patients with food allergy to soya (Roundup Ready) and maize (MON810, Bt11, Bt176) samples, as well as to the pure transgenic proteins (CryIA[b] and CP4 5-enolpyruvylshikimate- 3-phosphate synthase). Results: None of the individuals undergoing tests reacted differentially to the transgenic and nontransgenic samples under study. None of the volunteers tested presented detectable IgE antibodies against pure transgenic proteins. Conclusion: The transgenic products under testing seem to be safe in terms of allergenic potential. We propose postmarket testing as an important screening strategy for putative allergic sensitization to proteins introduced in transgenic plants.
- A Proteomic Study to Identify Soya Allergens- The Human Response to Transgenic versus Non-Transgenic Soya SamplesPublication . Batista, Rita; Martins, Isabel; Jenö, Paul; Pinto Ricardo, Cândido; Oliveira, Maria MargaridaBackground: In spite of being among the main foods responsible for allergic reactions worldwide, soybean (Glycine max) derived products continue to be increasingly widespread in a variety of food products due to their well-documented health benefits. Soybean also continues to be one of the elected target crops for genetic modification. The aim of this study was to characterize the soya proteome and, specifically, IgE-reactive proteins as well as to compare the IgE response in soya-allergic individuals to genetically modified Roundup Ready soya versus its non-transgenic control. Methods: We performed two-dimensional gel electrophoresis of protein extracts from a 5% genetically modified Roundup Ready flour sample and its non-transgenic control followed by Western blotting with plasma from 5 soya sensitive individuals. We used peptide tandem mass spectrometry to identify soya proteins (55 protein matches), specifically IgE-binding ones, and to evaluate differences between transgenic and non-transgenic samples. Results: We identified 2 new potential soybean allergens – one is maturation associated and seems to be part of the late embryogenesis abundant proteins group and the other is a cysteine proteinase inhibitor. None of the individuals tested reacted differentially to the transgenic versus non-transgenic samples under study. Conclusion: Soybean endogenous allergen expression does not seem to be altered after genetic modification. Proteomics should be considered a powerful tool for functional characterization of plants and for food safety assessment.
- Microarray analyses reveal that plant mutagenesis may induce more transcriptomic changes than transgene insertionPublication . Batista, Rita; Saibo, Nelson; Lourenço, Tiago; Oliveira, Maria MargaridaControversy regarding genetically modified (GM) plants and their potential impact on human health contrasts with the tacit acceptance of other plants that were also modified, but not considered as GM products (e.g., varieties raised through conventional breeding such as mutagenesis). What is beyond the phenotype of these improved plants? Should mutagenized plants be treated differently from transgenics? We have evaluated the extent of transcriptome modification occurring during rice improvement through transgenesis versus mutation breeding. We used oligonucleotide microarrays to analyze gene expression in four different pools of four types of rice plants and respective controls: (i) a gamma-irradiated stable mutant, (ii) the M1 generation of a 100-Gy gamma-irradiated plant, (iii) a stable transgenic plant obtained for production of an anticancer antibody, and (iv) the T1 generation of a transgenic plant produced aiming for abiotic stress improvement, and all of the unmodified original genotypes as controls. We found that the improvement of a plant variety through the acquisition of a new desired trait, using either mutagenesis or transgenesis, may cause stress and thus lead to an altered expression of untargeted genes. In all of the cases studied, the observed alteration was more extensive in mutagenized than in transgenic plants. We propose that the safety assessment of improved plant varieties should be carried out on a case-by-case basis and not simply restricted to foods obtained through genetic engineering.
- Uncertainty estimation and in-house method validation of HPLC analysis of carotenoids for food composition data productionPublication . Dias, M. Graça; Camões, M. Filomena G.F.C.; Oliveira, LuísaThe method for separation and quantitative determination of the main carotenoids in food by high-performance liquid chromatography (HPLC) was in-house validated. Tomato (Lycopersicon esculentum M.) as food matrix was used to demonstrate its linearity, repeatability, intermediate precision, detection and quantification limits, sensitivity and bias. In addition, stability of carotenoids was studied in function of temperature and time. Method accuracy was quantified through measurement uncertainties estimate based on this validation study. Furthermore, a study was conducted to evaluate variability coming from location in an experimental field composed by 12 subfields. The use of two metal free reverse phase columns and an organic mobile phase based on acetonitrile, methanol and dichloromethane enabled the separation of the six target compounds (trans-a-carotene, trans-b-carotene, b-cryptoxanthin, all-lycopene, lutein, zeaxanthin) within a 30 min run; detection at 450 nm and external calibration allowed the quantification of the analytes. Carotenoids concentration and measurement uncertainty, in mg/100 g, in tomato varieties ‘‘lido” and ‘‘for salad” were, respectively, 1.0 ± 0.14 and 0.39 ± 0.056 for trans-b-carotene, 8 ± 2.0 and 2.3 ± 0.57 for all-lycopene and 0.10 ± 0.017 and 0.08 ± 0.015 for lutein; trans-a-carotene, b-cryptoxanthin and zeaxanthin were not detected in both varieties (detection limits, in lg/100 g, 0.81, 0.57 and 0.77, respectively). For b-carotene and lutein, uncertainty associated with the entire process including small-scale within-region variation was statistically different, at a significance level of 5%, from measurement uncertainty (which includes sampling in the laboratory).
- Facts and fiction of genetically engineered foodPublication . Batista, Rita; Oliveira, Maria MargaridaThe generation of genetically engineered (GE) foods has been raising several concerns and controversies that divide not only the general public but also the scientific community. The fear and importance of the new technology, as well as commercial interests, have supported many of the ongoing discussions. The recent increase in the number of GE foods approved for import into the European Union and the increasingly global commercial food trades justify revisiting the facts and fiction surrounding this technology with the aim of increasing public awareness for well-informed decisions. Techniques that have recently become available for assessing food quality and its impact on human health, as well as the wealth of scientific data previously generated, clearly support the safety of commercialized GE products.
- Occurrence of Aflatoxins and Ochratoxin A in Baby FoodsPublication . Alvito, Paula; Sizoo, Eric A.; Almeida, Cristina M. M.; Egmond, Hans P.Infants have a more restricted diet and they generally consume more food on a body weight basis than adults. Therefore, the significance and potential health risk of any contaminant in foods consumed by infants is increased and diligent attention must be paid to this particular area. The present study aims to determine the occurrence of aflatoxin M1 (AFM1), aflatoxin B1 (AFB1) and ochratoxin A (OTA) in processed cereal-based foods (flours) and infant formulae (milk powder) available in the Portuguese market, both sold as conventional and organic origin. Mycotoxin determination was carried out using a method previously applied to duplicate diet samples. This method employed chloroform extraction, liquid–liquid extraction, immunoaffinity column (IAC) cleanup and HPLC analysis with fluorescence detection after postcolumn derivatisation. Quantification limits were 0.014, 0.004 and 0.028 μg kg− 1 for AFM1, AFB1 and OTA, respectively. These toxins could only be quantified in 12 of 27 analysed samples (15 positive results): two samples with AFM1, two samples with AFM1 and OTA, one sample with AFB1 and OTA and seven samples with OTA. Positive results concerned four for AFM1 (26%), one for AFB1 (7%) and ten for OTA (67%). For these samples, contents ranged between 0.017–0.041 μg AFM1 kg−1, 0.034–0.212 μg OTA kg−1, and one sample had a value of 0.009 μg AFB1 kg−1. Considering the presented results, we could provisionally conclude that the presence of these mycotoxins in baby foods does not constitute a public health problem. These are the first results concerning the occurrence of mycotoxins in marketed baby foods in Portugal and this is the first study using the HPLC method, proposed for duplicate diets, in baby food sample analysis.
- Study of the diffusion coefficients of diphenylbutadiene and triclosan into and within meatPublication . Silva, A. Sanches; Freire, J. M. Cruz; Losada, P. PaseiroThe migration of two chemicals, diphenylbutadiene and triclosan, was the target of this paper. Pork meat with different fat contents was prepared to study the influence of this parameter in the migration levels and to study the rate of diffusion of these migrants into the whole plastic/foodstuffs system and within the foodstuff. The whole system plastic/foodstuff diffusion coefficient (effective D) was calculated according to an equation based on the Fick’s Second Law, and D within the foodstuff (DF) was calculated according to the Moisan equation. At 5 C, DF was 1.6 9 10-7 and 1.7 9 10-7 cm2/s for DPBD and triclosan, respectively. At 25 C, DF was 3.7 9 10-7 and 3.9 9 10-7 cm2/s for DPBD and triclosan, respectively. As expected, D within the pork meat is faster than the whole system D, which means that the interface plastic/foodstuff may be the limiting step for the mass transport of chemicals from the packaging to the foodstuff.
- Overweight and obesity in infants and pre-school children in the European Union: a review of existing dataPublication . Cattaneo, A.; Monasta, L.; Stamatakis, E.; Lioret, S.; Castetbon, K.; Frenken, F.; Manios, Y.; Moschonis, G.; Savva, S.; Zaborskis, A.; Rito, A.I.; Nanu, M.; Vignerová, J.; Caroli, M.; Ludvigsson, J.; Koch, F.S.; Serra-Majem, L.; Szponar, L.; van Lenthe, F.; Brug, J.The objective of this study was to synthesize available information on prevalence and time trends of overweight and obesity in pre-school children in the European Union. Retrieval and analysis or re-analysis of existing data were carried out. Data sources include WHO databases, Medline and Google, contact with authors of published and unpublished documents. Data were analysed using the International Obesity Task Force reference and cut-offs, and the WHO standard. Data were available from 18/27 countries. Comparisons were problematic because of different definitions and methods of data collection and analysis. The reported prevalence of overweight plus obesity at 4 years ranges from 11.8% in Romania (2004) to 32.3% in Spain (1998-2000). Countries in the Mediterranean region and the British islands report higher rates than those in middle, northern and eastern Europe. Rates are generally higher in girls than in boys. With the possible exception of England, there was no obvious trend towards increasing prevalence in the past 20-30 years in the five countries with data. The use of the WHO standard with cut-offs at 1, 2 and 3 standard deviations yields lower rates and removes gender differences. Data on overweight and obesity in pre-school children are scarce; their interpretation is difficult. Standard methods of surveillance, and research and policies on prevention and treatment, are urgently needed.
- Analytical strategies to evaluate antioxidants in food: a reviewPublication . André, C.; Castanheira, I.; Cruz, J.M.; Paseiro, P.; Sanches-Silva, A.Antioxidants are an important group of food additives that have the ability to protect against detrimental change of oxidizable nutrients and consequently they extend shelf-life of foods. The present paper is an updated review on the analysis of ten antioxidants (both synthetic and natural). Three types of gallates, propyl (PG), octyl (OG) and dodecyl (DG), tert-Butylhydroquinone (TBHQ), Butylated Hydroxytoluene (BHT), tert- Butylhydroxyanisole (BHA), a-tocopherol, ascorbic acid, erythorbic acid and sodium D-isoascorbate were the antioxidants selected. The physico-chemical properties, sample preparation procedures and analytical methods for their determination are compared and discussed.