Browsing by Author "Cabral, Margarida"
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- Caracterização do Perfil em Aminoácidos de Duas Variedades de Arroz PortuguêsPublication . Mota, Carla; Cabral, Margarida; Torres, Duarte; Santos, Mariana; Castanheira, IsabelSegundo o INE, entre 2010 e 2011 o consumo humano de arroz branqueado e semibranqueado em Portugal foi de 15,8 kg/capita/dia, o que representa o valor mais elevado da Europa [1]. Tendo este alimento um largo consumo, a avaliação do seu perfil em aminoácidos (AA) pode ser importante para definir a qualidade das proteínas existentes nas diferentes espécies, possibilitando aos produtores a escolha de sementes com maior qualidade nutricional. Este trabalho teve como objectivo quantificar as proteínas totais e dezassete AA existentes em quinze sementes de arroz polido cultivado entre 2009 e 2011, correspondentes às variedades mais consumidas em Portugal, Japónica (carolino) e Indica (agulha), cultivadas nas regiões do Ribatejo e Sado. A proteína total foi determinada pelo método de Kjeldahl e a quantificação dos diferentes AA foi efectuada num sistema de Ultra Performance Liquid Chromatography UPLC® da Acquity™ (Waters), equipado com um detector de fotodiodos (DAD - photodiode array detection), com derivatização pré-coluna com 6-aminoquinolil-N-hidroxisuccinimidil carbamato [2], após hidrólise ácida das amostras em microondas. Da análise dos resultados salienta-se não haver diferença significativa entre variedades Japónica (6,42 ±0,5 g/100g) e Indica (7,0± 1,56 g/mg), relativamente ao teor de proteína total. Nas variedades estudadas, e de acordo a definição da WHO/FAO/UNU [3], a lisina foi o único AA limitante (Score <1). Nas amostras analisadas não foram observadas diferenças significativas entre o local de cultivo e ano de produção. Os resultados obtidos poderão ser agregados, possibilitando a inclusão de valores com maior representatividade nas Tabelas da Composição de Alimentos. [1] INE (2012) Balanços de aprovisionamento de Produtos Vegetais: Consumo humano de arroz branqueado e semibranqueado per capita (kg/ hab.) por Comprimento do grão; Anual - INE, Balanços de Aprovisionamento de Produtos Vegetais: http://www.ine.pt/xportal/xmain?xpid=INE&xpgid=ine_indicadores&indOcorrCod=0000186&contexto=bd&selTab=tab2 (05.04.2012) [2] WATERS CORPORATION (2006) UPLC Amino Acid Analysis Application Solution – System Guide. [3] WHO/FAO/UNU (2007) Protein and Amino Acid Requirements in Human Nutrition (Vol. 935). Geneva: WHO Technical Report Series.
- Protein content and amino acid profile in Portuguese ricePublication . Mota, Carla; Cabral, Margarida; Mauro, Raul; Torres, Duarte; Santos, Mariana; André, Catarina; Castanheira, IsabelAccording to INE, between 2010 and 2011, rice (Oryza sativa) availability in Portugal was 15.8 kg per capita per day, which represents the highest in Europe [1]. Rice amino acids profile evaluation is important to define the nutritional quality of different species contributing to choice of the varieties of rice to grow. This study aimed to quantify the total protein and amino acids profile in 15 cultivated accessions selected from the two major subspecies, Japonica and Indica, grown in Portuguese Sado and Ribatejo regions between 2009 and 2011. Total protein was determined by Kjeldahl method and the content of AA was measured by an Ultra Performance Liquid Chromatography of ACQUITY ™ UPLC ® (Waters) system equipped with a photodiode array detector (DAD) with a pre-derivatisation column 6-N-aminoquinolil hidroxisuccinimidil carbamate, after microwave acid hydrolysis. Analysis of the results emphasizes that there was no significant difference between Japonica varieties (6.4 ± 0.5 g/100g) and Indica (7.0 ± 1.6 g/100g) in relation to total protein content. Amino acids score, as defined by WHO/FAO/UNU [2], was between 0.55 (lysine) and 3.24 (aromatic amino acids). Lysine was the only limiting AA (score <1). No significant differences were observed in amino content between subspecies, cultivation region and year of crop. The obtained results may be aggregated and include in the Portuguese Food Composition Databank and EuroFIR Food Platform [3]. Research on wholegrain and husk rice properties is underway and will be discussed.
- The Nutritional Characterization of Rice Varieties Consumed in PortugalPublication . Mota, Carla; Santos, Mariana; Nascimento, Ana; Gueifão, Sandra; Coelho, Inês; Cabral, Margarida; Torres, Duarte; Castanheira, IsabelBackground and objectives: Portugal has the largest consumption of rice 15.8 kg/capita/year, in Europe. The present work aims to evaluate: rice nutritional profile, namely proximate, amino acid and mineral composition; arsenic content, as the most abundant contaminant and, compositional differences between varieties, year and place of harvest. Methods: Samples were collected from the most representative national rice producers. Analysis was carried out by following analytical methods: proximate by AOAC methods; amino acids by UPLC-DAD; starch, and amylase by enzymatic methods; mineral analysis by ICP-OES including copper, manganese, iron, zinc, magnesium, calcium, sodium, phosphorus and potassium and arsenic content by ICP-MS. Results: Analyzed rice showed higher amylopectin (54.7 ± 7.3 g/100g) content than amylose (33.5± 3.8 g/100g) and total protein content of 7.1 ± 0.3 g/100g a low content of fiber and fat (<1 g/100 g) was found. The most abundant essential amino acids were aromatic amino acids with a 7.5% of total protein. The most abundant minerals were potassium and phosphorus with levels ranging from 91 mg/100g to 107 mg/100g.The arsenic content was determined by ICP-MS and the values were below 600 µg/kg. Conclusions: Crop place showed to be the major source of variation in amino acid content. With respect to protein quality, cysteine, lysine, sulfur amino acids and isoleucine were considered limiting with protein digestibility corrected amino acids scores (PDCAAS) lower than 1. To assure the nutritional requirements for amino acids and subsequent protein synthesis, rice consumption must be followed by other food groups (e.g pulses, meat products) in order to provide the other essential amino acids. Rice contribution for mineral intake ranged from 3% DRI (iron and potassium) to 36 % DRI (manganese). In this study, a very weak correlation between arsenic levels and amino acid content was observed.