Browsing by Author "Santos, Mariana"
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- Accuracy evaluation in thiamin quantification in food matricesPublication . Flores, Cristina; Dias, M. Graça; Santos, MarianaThe performance evaluation of an RP-HPLC method to determine thiamine using different food matrices and reference materials, showed the method suitability to its purpose and to be submitted to accreditation. Intermediate precision evaluate through the relative standard deviation (RSD%) was under 8% for all food matrices tested an all the z-scores obtained for the reference materials were < 1.5.The estimated expanded measurement uncertainty was 13%.
- Accuracy in niacin quantification in food matrices, by an RP-HPLC methodPublication . Flores, Cristina; Dias, M. Graça; Santos, MarianaAim: This work intended to evaluate accuracy of niacin quantification in food matrices, by an RP-HPLC method, in order to validate it for four different food groups: legumes, grains, dairy products and fish. Material and methods: Analytical methodology The analytical method was a RP-HPLC with fluorometric detection, based on EN 15652:2009. Samples (1 to 10 g) were submitted to an acid hydrolysis with 0.1 mol/l HCl for 30 min in an autoclave at 121ºC. After filtration, 50 µl of the solutions, were injected and separated at 37 ºC on a HPLC system. The stationary phase was the Fortis C18 5 µm (150 x 4,6 mm) column and the mobile phase consisted of 0.07 mol/l phosphate buffer, 0.075 mol/l hydrogen peroxide and 5x10-6 mol/l copper sulphate, at a flow rate of 1 ml/min. Excitation and emission wavelengths were 322 nm and 380 nm, respectively. Quantification was made with five external standards. Results were expressed in mg/100g. Accuracy evaluation To evaluate precision, at least one matrix of each food group was chosen: roasted peanuts, canned green peas, wheat bran, powder milk and canned tuna. Method trueness was assessed by testing five different reference materials from FAPAS and NIST. Each of the FAPAS samples 2160, 2166, 2172, 2176 (Breakfast Cereals) were tested once over a period of 14 months and, NIST 1849 (Infant/Adult Formula) was tested twice in the same period. In the precision study, the five matrices were tested in triplicate in four different days. Repeatability and intermediate precision standard deviations (Sr and SPi) were calculated, for each matrix, trough ANOVA (p < 0.05). Repeatability and Intermediate precision limits; r and Pi were calculated using the following formulas: r=2.8*S_r and Pi=2.8*S_Pi . Trueness was evaluated from the z-scores obtained. Results: The values of niacin concentration obtained were: peanuts – 13.4 mg/100 g, green peas – 0.59 mg/100 g, wheat bran – 18.2 mg/100 g, powder milk – 0.73 mg/100 g and tuna – 9.5 mg/100 g. The Sr and SPi (mg/100g) were respectively 0.52 / 1.25 (peanuts), 0.02 / 0.05 (green peas), 0.23 / 0.78 (wheat bran), 0.02 / 0.06 (powder milk) and 0.24 / 0.60 (tuna). The r and Pi values obtained ranged from 0.05 to 1.46 for r and 0.14 to 3.50for Pi. All the │z-scores│ obtained for FAPAS samples were < 1 and, the │z-scores│ obtained for NIST reference material were both < 2. Conclusion: The repeatability data obtained in this study, for niacin in different food matrices were in accordance with the ones presented in the method standard EN 15652:2009. Trueness evaluation using breakfast cereals and formulas revealed a good method/laboratory performance. Accuracy evaluation, using representative matrices and niacin contents, showed the method suitable to its purpose and fit to be submitted to accreditation by an external entity.
- Afinal, é ou não seguro consumir regularmente pescado?Publication . Santiago, Susana; Namorado, Sónia; Dias, Carlos; Martins, Carla; Santos, Mariana; Carvalho, Cristina; Assunção, RicardoConsumo de pescado em Portugal, Riscos e beneficios do consumo de pescado, Metilmercúrio (MeHg), População mais suscetível ao MeHg, Avaliação da exposição ao MeHg, Recomendações para o consumo de pescado.
- Alimentação saudável - Roda dos AlimentosPublication . Viegas, Silvia; Fernandes, Paulo; Santos, MarianaRecomendações para uma alimentação diária mais saudável, por grupos de alimentos.
- A análise laboratorial e a rotulagem de géneros alimentícios destinados a uma dieta isenta de glútenPublication . Matias, Filipa; Santos, Mariana; Calhau, Maria AntóniaA segurança dos alimentos continua a mobilizar todos os intervenientes da cadeia alimentar, desde os operadores económicos aos consumidores. Desta forma, a rotulagem tem-se revelado uma importante ferramenta na decisão de compra: o rótulo constitui o primeiro elo de ligação entre o produto e os consumidores. Fornecendo-lhes informação relevante acerca do produto, permite-lhes fazer escolhas conscientes, saudáveis e seguras, em especial àqueles que sofrem de alergias ou intolerâncias alimentares. Hoje em dia, o número de pessoas com intolerância ao glúten tem vindo a aumentar e, neste sentido, a Indústria alimentar tem demonstrado uma maior preocupação em produzir alimentos que possam ser consumidos, em segurança, por este grupo de pessoas. De acordo com o regulamento nº 1169/2011, já em vigor, é obrigatório incluir no rótulo referência às substâncias ou produtos que provocam alergia ou intolerância alimentar. A nível europeu, os alimentos destinados a uma alimentação especial têm um regulamento próprio, o nº 41/2009, aplicável desde Janeiro de 2012, relativo à composição e rotulagem de géneros alimentícios adequados a pessoas com intolerância ao glúten. De forma a cumprirem este regulamento, e a fim de inserirem informação fidedigna nos rótulos dos alimentos, as empresas da Indústria alimentar recorrem ao Laboratório de Química para serem realizadas análises de detecção e quantificação de glúten em novos alimentos a colocar no mercado. O Laboratório também tem colaborado com a Entidade de Controlo Oficial e com uma Associação de Apoio ao Doente Celíaco, num programa de monitorização de alimentos destinados a uma alimentação especial, com o objectivo de avaliar alimentos rotulados como “isento de glúten”. A fim de avaliar a veracidade desta informação, são analisados géneros alimentícios colhidos em diversas superfícies comerciais. Com este trabalho laboratorial, pretendeu-se analisar o conteúdo em glúten, em amostras provenientes da Indústria alimentar, e avaliar a conformidade da rotulagem relativa à informação “isento de glúten”, em amostras provenientes do programa de monitorização. Neste âmbito, o Laboratório de Química analisou, no último triénio, 48 amostras usando o método imunoenzimático ELISA-R5 (RIDASCREEN® Gliadin). Nas amostras provenientes da Indústria Alimentar, os resultados obtidos, inferiores ao limite de detecção, permitem que a menção “isento de glúten” possa ser inserida nos rótulos dos alimentos analisados. Relativamente ao programa de monitorização, os resultados confirmaram a menção “isento de glúten” apresentada nos rótulos, ou seja, todos cumpriam o limite de 20 mg/Kg. O Laboratório de Química tem dado e continua a dar um relevante e decisivo contributo para que os doentes celíacos possam consumir, com confiança, os alimentos disponíveis no mercado adequados a uma dieta isenta de glúten, permitindo a prática de uma alimentação mais segura.
- Application of nutritional profile models to commercially available baby foods products (6-36 months) in two regions of Lisbon (ToR 4)Publication . Santos, Mariana; Assunção, Ricardo; Matias, FilipaToR 4 Main Activity: Implementation of Nutrient Profile tools to support marketing regulations and policies on foods consumed bychildren aged below 36 months in Eurasian Economic Community (EurAsEC) and/or neighbour countries.
- Assessment of Digestion Methods to Assist Mineral Analysis of Purple Corn, Quinoa, Amaranth and Buckwheat by ICP-OESPublication . Nascimento, Ana Cláudia; Santiago, Susana; Santos, Mariana; Coelho, Inês; Gueifão, Sandra; Castanheira, Isabel; Samman, Norma; Calhau, Maria AntóniaPurple corn (Zea mays L.), quinoa (Chenopodium Quinoa) and amaranth (Amaranthus caudatus) are a cereal and pseudocereals of Andean origin, largely consumed in North of Argentina. Buckwheat (Fagopyrum esculentum) is a pseudocereal with an important role in food diets around the world, especially in Asia and Eastern Europe. They gained increasing attention of scientific community, specially due to their high nutritional value and health benefits. Mineral concentrations in cereals and pseudocereals can differ with genotype, type of soil, fertilizer application, region’s mineral composition and treatments applied, that can even cause the loss of some minerals. Analytical values must be obtained by applying high quality criteria, such as criteria on sample handling, appropriate sample preparation and subsequent analytical method and, an effective internal and external quality control program. Inductively Couple Plasma Atomic Emission Spectrometry – ICP-OES is a high specific technique which allows a rapid and simultaneous multi-elemental analysis of several elements, in a numerous and wide scale of sample matrices, with good detection limits. A previous sample decomposition through its dissolution is required which can be undertaken by different methods, namely microwave digestion, dry-ashing, wet digestion. The destruction of organic matter is a slow step of overall analytical process largely dependent on the content of major components. The purpose of this work was to compare the performances of microwave and dry-ashing digestion procedures, including the optimization of microwave conditions to assist ICP-OES analysis. The optimized digestion method was applied on determination, of copper, manganese, iron, zinc, magnesium, calcium, phosphorus, sodium and potassium contents in purple corn, quinoa, amaranth, buckwheat and rice. Samples were dry ashed within platinum capsules in a furnace at 470 ºC during 40 h and microwave digested using a closed-vessel system digestion with a mixture of concentrated acid nitric, hydrogen peroxide and deionised water. The accuracy of analytical procedure was verified by analyzing a NIST 1548a reference material. Mineral profiles of purple corn, pseudocereals and rice were compared. Copper ranged from 0.07 mg/100g (rice) to 0.59 mg/100g (quinoa), manganese ranged from 0.64 mg/100g (purple corn) to 1.73 mg/100g (quinoa), iron ranged from 0.2 mg/100g (rice) to 8.8 mg/100g (amaranth), zinc ranged from 1 mg/100g (rice) to 5.1 mg/100g (amaranth), magnesium ranged from 27 mg/100g (rice) to 211 mg/100g (amaranth), calcium ranged from < 10 mg/100g (rice) to 154 mg/100g (amaranth), phosphorus ranged from 105 mg/100g (rice) to 480 mg/100g (amaranth), potassium ranged from 90 mg/100g (rice) to 587 mg/100g (quinoa). By comparing purple corn and pseudocereals with rice, pseudocereals presented the highest mineral content as expected. Also, for almost all minerals, purple corn showed higher mineral amounts than rice. These results showed that purple corn and pseudocereals understudy can be added to diets, with already known improved nutritional benefits. Statistically there was no evidence that the two different digestion methods applied have influenced final results, as P value was considered to be not significant (P > 0.05). However, microwave digestion enabled a more effective control of contamination or losses than dry-ashing, with less time consuming dispended.
- Assessment of food claims and nutritional quality on baby foodsPublication . Matias, Filipa; Vaz, Rui; Assunção, Ricardo; Santos, Mariana; Castanheira, IsabelIntroduction: As the use of commercially available complementary foods (CACFs) has increased, it became crucial that appropriate infant feeding is protected and consumers are not mislead by statements about the composition of the product or its nutrition or health related properties. WHO published a report which proposed criteria for identifying products appropriate for promotion for infants and young children (IYC) up to 36 months. Aims: This study investigated the food claims available on CACFs and its relation with nutritional quality, using the set of criteria developed by WHO.
- Assessment of the gluten content in gluten-free labelled foodstuffsPublication . Nunes Matias, Filipa; Santos, Mariana; Calhau, Maria AntóniaFood labelling helps consumers to get important information about the food they consume, this information is particularly important for those with food intolerances, like celiac patients. As the number of persons with gluten intolerance increases, the food industry demonstrates a greater concern to produce food that can be safely consumed by this group of people. In accordance to the European Regulation No 1169/2011, it’s mandatory to include the substances or products that cause allergies or intolerances on the label. At European level there is a great concern with this type of food intolerance, therefore foodstuffs intended for particular nutritional use have a specific regulation (No 41/2009). This regulation, applicable since past January, concerns the composition and labelling of foodstuffs suitable for people with gluten intolerance. In order to comply with this regulation, and to insert reliable information on the food labels, our laboratory works with the food industry companies and carry out analyses for detection and quantification of gluten in food and raw materials. Our laboratory also collaborates with the Portuguese Food Safety Authority (ASAE) in the programme for monitoring food intended for particular nutritional uses, which includes the food labelled as gluten-free. In order to access if the information gluten-free was being correctly applied on the labels, foodstuffs from different brands were analysed. With this study we evaluated the conformity of labelling, connected with gluten-free information, in 35 samples. Gluten analysis was performed using two different immunoenzimatic assays: RIDASCREEN® Gliadin and/or RIDASCREEN® Gliadin competitive. All the samples analysed in the study contained levels of gluten below the 20 mg/Kg limit proposed by the Codex Alimentarius Commission for gluten-free foods. These results were in agreement with the information gluten-free presented on the sample labels. This study underlines the importance of the laboratory in ensuring that the information gluten-free on the labels is reliable, so people with food intolerances, like the celiac disease, can safely consume this products.
- Assessment of the salt content in school mealsPublication . Santiago, Susana; Nascimento, A.; Santos, MarianaSchool lunch is an important opportunity for start learning healthy eating habits and shall ensure a nutritionally balanced food supply. Balanced school meals are linked to improved concentration in class and improved academic outcomes. The report from FAO 2019 “Nutrition guidelines and standards for school meals” refers that more emphasis should be given on setting upper limits for saturated fat, sugar and sodium, especially in contexts where overweight and obesity are prevalent among schoolchildren. According to IAN-AF (2015-2016) the average daily consumption estimated of salt is for children (<10 years) 5.4 g/day and for adolescents (11-17 years) 7.2 g/day. The WHO recommends maximum level intake of 5 g/day of salt in adults should be adjusted downward based on the energy requirements of children relative to those of adults, in order to control blood pressure. The purpose of this study was to assess the salt content of the main components of school meals, collected in diferent schools of Lisbon region and to evaluate the contribution of the diferent components to the salt content of meal. These results were also compared to established guidelines and nutritional recommendations for school meals. Meals were analyzed from 12 diferent schools, consisting of bread, soup and main course. The samples were analyzed by optical emission spectrometry with coupled inductive plasma (ICP-OES) after acid digestion, for determination of sodium content, in accordance with the requirements of EN ISO / IEC 17025. Salt content was calculated by formula salt = sodium × 2.5. The amount of salt provided from the components of the school meals ranged between 0.2 and 0.9 g/meal in bread, 0.2 and 1.7 g/meal in soup and 0.6 and 2.9 g/meal in main course. The component that contributed most to the sodium content of the meal was the main course. These results suggest that the salt content of school meals should be controlled by monitoring, with gains in children's health. Once the values remain far above the WHO recommendation for salt consumption, it is necessary to go even further in salt reduction and extend this intervention to other Portuguese schools.