Progressing towards the construction of METROFOOD-RI

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Development of a digestion method to assist multi-element determination in Rocha pear by ICP-MS

Publication . Castanheira, Isabel; Coelho, Inês; Teixeira, Rita; Ventura, Marta

The Rocha pear is a Portuguese variety of pear (Pyrus communis L.), harvested in August but available for consumption practically all year round, due to the refrigeration process. The West region of Portugal is classified as Protected Designation of Origin (PDO). This variety is responsible for 95% of the national pear production and represents an important economic activity with exportations over 67 million Euros per year. In the present work a method for pear digestion, prior to analysis by ICP-MS, has been developed and optimized. The elements analyzed were Cr, Mn, Co, Ni, Cu, As, Se, Sr, Mo, Cd, Sn and Pb. After the removal of seeds pear samples were freeze-dried and vacuum sealed until analysis. A graphite heating block (digiprep) was used for sample digestion. For method development different combinations of sample weight; high purity nitric acid; high purity hydrogen peroxide and digestion conditions were compared. The results showed that weighing more than 0.7g of sample leads to an incomplete digestion evidenced by the presence of solid residues in the digestion tube. The same was noticeable in samples that had not been soaked in nitric acid overnight. In all analyzed samples Se, Sn and Pb were below the limit of quantification. This work concludes that the most suitable digestion method for freeze dried pears is obtained by adding 8ml of ultrapure HNO3 to 0.7g of sample. Samples are left in acid overnight and digested in a heating block for 130 min at 95°C on the next day.

2017-10Conference object

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Emerging and persistent inorganic contaminants in prioritized foods: results from Portuguese Total Diet Pilot Study

Publication . Ventura, Marta; Coelho, Inês; Delgado, Inês; Gueifão, Sandra; Costa, Maria Helena; Castanheira, Isabel

Total diet studies (TDS) provide analytical data to estimate dietary exposure and risk assessment of contaminants. TDS were adopted by several European countries as the sound scientific basis for strength the linkage between food consumption and food analysis with the purpose to assess the effect of harmful substances on health. Heavy metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the World Health Organization (WHO). Bromine is a halogen of emerging concerned and has been associated with endocrine disruption and subject to bioaccumulation in food chains. The aim of this work was to study the profile of chemical contaminants; lead chromium, cadmium. Arsenic and bromine as a contaminant of emerging concerned in foods collect in Portuguese TDS pilot study. Four hundred and eighty foods were purchased and prepared as consumed were pooled in forty laboratory samples. Then were digested with concentrated nitric acid and hydrogen peroxide in a microwave system for Pb, Cr, Cd and As, total bromine was determined using tetramethyl ammonium hydroxide (TMAH) extraction. Digested samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS) and HPLC-ICP-MS for total and chemical species respectively. Analytical procedures were carried out under rigorous metrological control, laboratory performance was demonstrated through a successful participation in PT schemes runs by an accredited provider. The decreasing sequence of the mean inorganic contaminants in prioritised foods was as follows: As > Br > Cr > Pb > Cd. In Octopus was found the highest amount of As, 9138 ± 237 μg/kg, mainly arsenobetaine and in clams were detected the highest concentrations of Cd and Pb, 125 ± 17 μg/kg and 260 ± 23 μg/kg, respectively. The results of TDS Portuguese Pilot study showed that contents of inorganic chemical contaminants are similar to those published by studies carried out in other European Countries. Based on studies published we can inferred that intake of inorganic substances do not pose a risk to Portuguese population.

2017-11Conference object

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Evaluation of iodine content in Portuguese primary school meals after mandatory iodization program

Publication . Delgado, Inês; Coelho, Inês; Nobre, Daniela; Castanheira, Isabel; Calhau, Maria Antónia

Clinical studies in Portugal have demonstrated the existence of a generalized deficiency in iodine of pregnant women and with school-age children. A general lack of awareness within the Portuguese population about the importance of iodine in the diet has also been identified. Thus, in this work we report the program underway in country to monitor the real content of iodine in school meals. Collection of foods from schools was designed to represent school meal program in place. Foods were organized into three groups. One hundred and forty four samples cooked with iodization salt (soup and main course) were collected from primary schools across Lisbon District (Group I). Twelve samples were used as reference of real iodine content from a pilot school (Group II). One hundred and forty four samples composed according consumption data were used as reference of minimum iodine value (Group III). A total of three hundred samples were analysed in pooled or single corresponding to thirty six laboratory samples and analysed in triplicate. The iodine contents were determined by inductively coupled plasma-mass spectrometry (ICP-MS) after alkaline extraction with TMAH (tetramethylammonium hydroxide) in a graphite block system during 3 hours at 90 °C, under the frame of ISO/EN 17025:2005 and EN 15111:2007. Laboratory performance was demonstrated through a successfully participated in Proficiency Testing Schemes launched by accredited provider. The concentration of iodine in analysed samples showed a wide range of levels varying according to the group. Group I from 9.9 µg/100g in chicken to 23.2 µg/100g in fish. Group II the highest value (32.3 µg/100g) was found in soup. The lowest value (below limit of quantification) was found in meat of Group III. The ratio between Group I and Group III was used to estimate effectiveness of the program, and the biggest difference was found in fish and narrowest was determine in chicken. The distance between iodine content in Group I and Group II was used to monitoring bias due to pooled samples. The major difference was observed in turkey. Sodium content is discussed as a contribution to clarify the iodine differences. Cooking procedure, iodization salt absorption, and operator performance were identified as main factors contributing to the differences between real and prescribed content. Iodization salt content determined in foods as consumed is an appropriate approach to evaluate fortification program and risks of both inadequate and excess iodine intake.

2017-11Conference object

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´Rocha’ pear antioxidant and mineral characterization

Publication . Coelho, Inês; Rego, Andreia; Teixeira, Rita; Nascimento, Ana; Bordado, João; Santos, Rui; Castanheira, Isabel

Introduction: ‘Rocha’ pear (Pyrus communis L.) is a Portuguese native variety with a Protected Designation of Origin (PDO). This variety is responsible for 95% of the national pear production and represents an important economic activity1 with exportations over 67 million Euros per year2. Pears are very nutritive fruits, rich in micronutrients, antioxidants and other important nutrients. Its nutritional value has been widely studied. However, in comparison to other European pears like Bartllet and Red Anjou, whose nutritional value is well known and published in reference databases, ‘Rocha’ pear’s nutritional quality has been less studied. Objectives and methodology: The objective of this study was to evaluate an antioxidant and mineral characterization of ‘Rocha’ pear. Antioxidant capacity was characterized by testing the elimination of free radicals DPPH (2,2-diphenyl-1-picrylhydrazyl) and by the Folin-Ciocalteau method. Minerals and trace elements were quantified by ICP-MS and ICP-OES after a graphite heating block (digiprep) digestion. Elements analyzed were Cr, Mn, Co, Cu, Se, Sr, Mo, Sn, Zn, Fe, Mg, P, K, Ca and Na. ‘Rocha’ pear samples were collected from 11 farms in 2 Portuguese regions (Fundão and PDO region). Each laboratory sample was a pool of three pears. One sample was used to study differences between peel and pulp. After the removal of seeds pear samples were freeze-dried and vacuum sealed until analysis. Main findings: The PDO pears have the highest antioxidant capacity, presenting a phenolic content ranging from 0,65 to 0,84 mg eq. Galic acid/ g sample and an IC50 from 0,26 to 0,17 mg/ml. As expected the majority of compounds with antioxidant proprieties are in the peel, with proximally two times more than the pulp. In terms of micronutrients no significant differences were found between the regions under study. The exception is zinc and sodium that presents higher values for the PDO region. Conclusions: In conclusion, it is important to study and to divulge the Portuguese pear in a higher extension, once it will lead to a higher consumption by the population and consequently to a national economic growth.

2017-10Conference object

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Abundance of Selenium and Selenoproteins in foods consumed in Portugal

Publication . Gueifão, Sandra; Sanches, Diana; Delgado, Inês; Coelho, Inês; Ventura, Marta; Castanheira, Isabel

Selenium (Se) is an essential element for human health. Dietary levels in the population are positively correlated to selenium content in foods as consumed. Dietary Reference Intake for Se is 55 μg/day for adult men and women. However, depending on the species, oxidation state and concentration Se can be toxic to human health. Accurate determination of Se content in the diet demands information not only on total Se (tSe) but also on the bioaccessible species presented in food samples [1]. The aim of this work was to evaluate the concentration of tSe and Se species as Selenomethionine (SeMet), Selenite (SeIV) and Selenate (SeVI) in cow milk, cabbage and fish samples consumed in Portugal. Accurate analysis of tSe was carried out by ICP-MS preceded by acid digestion in a closed-vessel microwave system. Several approaches for extraction of Se species from food matrices were studied followed by quantification with HPLC-ICP-MS. The reliable conditions of analytical procedures were achieved with metrological tools operated under the frame of ISO/EN 17025:2005. tSe content ranged from 67 ± 3 ug.kg-1 (cabbage), 161 ± 16 ug.kg-1 (milk) and 988 ± 27 ug.kg-1 (fish). SeMet was major selenium species in milk and fish samples accounting for 85 -90 % of tSe content. In cabbage Se (IV), Se (VI) and (SeMet) were found. The results showed the suitability of analytical procedure to measure tSe and seemed effective to achieve an accurate determination of Se species in these complex matrices. References: [1] Bodnar, M., Szczyglowska, M., Konieczka, P., Namiesnik, J. Methods of Selenium Supplementation: Bioavailability and Determination of Selenium Compounds. Critical Reviews in Food Science and Nutrition. 2016. 56: 36-55.

2017-10Conference object

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