Browsing by Author "Oom, M."
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- Antioxidant capacity, phenolic content and total flavonoids of orange juicePublication . Raposo, C.A.; Albuquerque, T.G.; Oom, M.; Sanches-Silva, A.; Costa, H.S.Nowadays, the search for healthier dietary food choices has increased the demand for fresh and nutritive products. Several epidemiological studies indicate that fruits, vegetables and less processed food ensure a higher protection against diseases caused by oxidative stress. Citrus juices attract attention as a result of their health-related properties, due to the presence of natural antioxidants. Orange juice, in particular, is one of the most consumed juices worldwide and it is an important source of flavonoids and phenolic compounds. As a result of the development of new technologies and the improvement of traditional industrial processing, there is a wide range of new commercial juices promoted by strong marketing strategies. In fact, it is important to evaluate whether these processed products maintain similar properties to a freshly squeezed juice. The main objective of the present work was to evaluate the antioxidant activity of six samples of orange juice: one nectar, three concentrated juices, and two freshly squeezed juices (filtrated and non-filtrated). The oranges and orange juices were acquired in local supermarkets, and the antioxidant activity was determined comparing three different methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH●), Folin-Ciocalteu method (applied to determine total phenolics, using gallic acid as standard) and total flavonoids assay (using epicatechin as standard). All the analyses were performed at least in duplicate. For DDPH● assay, the EC50 value (inversely proportional to antioxidant activity) was higher for the nectar (13.8 ± 0.33 mg/mL), followed by freshly squeezed juices (12.6 ± 0.59 and 12.3 ± 0.22 mg/mL, filtrated and non-filtrated, respectively) and concentrated juice (9.01 ± 0.03 mg/mL). The highest value for total phenolics was found in concentrated juices (0.208 ± 0.04 mg/mL), whereas the lowest corresponds to the orange nectar (0.134 ± 0.00 mg/mL). With respect to total flavonoids content, the values varied between 0.099 ± 0.00 and 0.158 ± 0.01 mg/mL, for nectar and concentrated juices, respectively. Our results indicated that orange juice can be considered a good source of natural antioxidants, including flavonoids and phenolic compounds. The methods for antioxidant activity evaluation showed that orange nectar had the lowest antioxidant capacity, whereas the concentrated juices presented the highest. There is no evidence that filtration of the freshly squeezed juice produced considerable variations. Although the industrial processing of orange juice may cause losses of vitamin C, it is a common practice of food industry to add L-ascorbic acid at the end of the processing. In fact, commercial concentrated juices revealed higher values of antioxidant activity, flavonoids and phenolic compounds, than the freshly squeezed juices.
- Nutritional composition of commercial orange juicesPublication . Raposo, C.A.; Albuquerque, T.G.; Oom, M.; Sanches-Silva, A.; Costa, H.S.In the context of a healthy diet, fruits contribute to a decrease in the incidence of cardiovascular disease and cancer. They are considered to have multiple beneficial health effects and are an essential part of the Mediterranean Diet. Orange in particular, is broadly consumed worldwide by different age groups, but mainly as juice. Food composition databases (FCDB) are resources providing detailed information on the nutritional composition of foods, usually from a particular country. The aim of the study was to determine the nutritional composition of four samples of commercial orange juices (one nectar, and three concentrated juices) and to contribute for the update of Portuguese FCDB. The orange juices were acquired in local supermarkets. Packages of the analysed samples were randomly chosen and corresponded to different batches. According to the label the concentrated juices were 100% orange juice (juice and pulp). The content of water, ash, total protein, total fat, total dietary fibre and sugars were determined. The energy value (kJ/kcal) was calculated. Water was the major constituent in the analysed samples and varied between 88.6 ± 0.0 g/100 g of edible portion (nectar), and 93.0 ± 0.0 g/100 g of edible portion (concentrated juices). Regarding the total protein and total fat contents, the lowest value was observed in the nectar, and the highest values in the concentrated juices. The present study will contribute with new and reliable data for inclusion in the Portuguese FCDB. Food composition data are important in many fields, namely government nutrition policies, public health and education, and for the food manufacturing industry.
- Nutritional composition of four samples of commercial orange juicePublication . Raposo, C.A.; Albuquerque, T.G.; Oom, M.; Sanches-Silva, A.; Costa, H.S.In the context of a healthy diet, fruits contribute to a decrease in the incidence of cardiovascular disease and cancer. They are considered to have multiple beneficial health effects and are an essential part of the Mediterranean Diet. Orange in particular, is broadly consumed worldwide by different age groups, but mainly as juice. Food composition databases (FCDB) are resources providing detailed information on the nutritional composition of foods, usually from a particular country. However, with industry development, the range of products is rising, and it is important that the information supplied by FCDB can follow this exponential growth. Evaluating the nutritional profile of different types of orange juice available in the market, contributes to determine possible differences between equivalent products. The aim of the study was to determine the nutritional composition of four samples of commercial orange juices (one nectar, and three concentrated juices) and to contribute for the update of Portuguese FCDB. The orange juices were acquired in local supermarkets, and only the edible portion was analysed. Packages of the analysed samples were randomly chosen and corresponded to different batches. According to the label the concentrated juices were 100% orange juice (juice and pulp). The content of water, ash, total protein, total fat, total dietary fibre and sugars were determined. The energy value (kJ/kcal) was calculated. Water was the major constituent in the analysed samples and varied between 88.6 ± 0.0 g/100 g of edible portion (nectar), and 93.0 ± 0.0 g/100 g of edible portion (concentrated juices). Regarding the total protein and total fat contents, the lowest value was observed in the nectar, and the highest values in the concentrated juices. For total protein the content varied between 0.319 ± 0.0 and 0.615 ± 0.0 g/100 g of edible portion. With respect to total fat the obtained values ranged from 0.067 ± 0.0 0.125 ± 0.00 g/100 g of edible portion. The present study will contribute with new and reliable data for inclusion in the Portuguese FCDB. Food composition data are crucial to the quantitative study of nutrition and are important in many fields, namely government nutrition policies, public health and education, and for the food manufacturing industry.
- Perfil nutricional e avaliação da actividade antioxidante de sumo de laranjaPublication . Raposo, C.A.; Albuquerque, T.G.; Oom, M.; Sanches-Silva, A.; Costa, H.S.Introdução: Os frutos e vegetais constituem uma parte essencial da dieta mediterrânica, e o seu consumo está associado a uma diminuição da mortalidade por doença cardiovascular e cancro. Os citrinos são reconhecidos por apresentarem elevada actividade antioxidante. A laranja, em particular, é amplamente consumida em todo o mundo, principalmente sob a forma de sumo. Durante o processamento industrial destes sumos, ocorrem alterações consideráveis, nomeadamente no que diz respeito ao teor em compostos bioactivos e vitaminas. A determinação da actividade antioxidante é frequentemente o primeiro passo na avaliação do conteúdo em compostos bioactivos antioxidantes de uma matriz alimentar. Objectivos: Determinar a composição nutricional e avaliar a actividade antioxidante in vitro de sumo de laranja comercial. Métodos: Os sumos, provenientes de sumo e polpa de laranja concentrados, foram adquiridos em superfícies comerciais da região de Lisboa. Determinaram-se os teores de água, cinza, proteína, gordura total e fibra alimentar. Foram calculados o teor total de hidratos de carbono disponíveis e valor energético. Para avaliar a actividade antioxidante in vitro foram utilizados: o ensaio do DPPH● (2,2-difenil-1-picril-hidrazilo), a determinação de polifenóis totais e de flavonóides totais. Resultados: O teor de água do sumo de laranja foi de 89,3 ± 0,05 g/100 g de parte edível. No que diz respeito aos teores de gordura, cinza e proteína, os valores foram de 0,125 ± 0,0; 0,340 ± 0,0; e 0,574 ± 0,0 g/100 g de parte edível, respectivamente. O valor de EC50 (concentração do extracto que dá origem à redução de 50% da absorvência do DPPH●, valor que é inversamente proporcional à actividade antioxidante) para o sumo de laranja foi de 10 mg/mL. O teor de polifenóis e de flavonóides totais foi de 0,208 ± 0,04 mg de equivalentes de ácido gálico/mL e de 20,2 ± 1,20 mg de equivalentes de epicatequina/mL, respectivamente. Conclusões: De acordo com os resultados obtidos pode verificar-se que o sumo de laranja é fonte de antioxidantes naturais, nomeadamente polifenóis e flavonóides totais. Relativamente ao teor de fibra alimentar, verifica-se que os sumos de laranja apresentam um teor inferior ao da laranja. Futuramente realizar-se-ão ensaios analíticos de comparação com outros sumos de frutos não processados.
- Vitamin C content: fresh homemade vs. commercial orange juicesPublication . Raposo, C.A.; Albuquerque, T.G.; Oom, M.; Sanches-Silva, A.; Costa, H.S.Introduction: Citrus juices are important sources of health-promoting compounds. Orange juice, in particular, is rich in natural antioxidants, such as vitamin C. Human plasma levels of L-ascorbic acid are entirely dependent on dietary sources, such as fruits and vegetables, since we are unable to synthesize this vitamin. Moreover, evidence shows that in a great percentage of the population, plasma levels of this vitamin are suboptimal for the beneficial health effects of vitamin C. This important compound acts as an antioxidant, reducing the risk of cardiovascular diseases, arteriosclerosis and some forms of cancer. Dietary Reference Intake (DRI) for vitamin C was established by the Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences. Values given for healthy males and females, >19 years, are 90 mg/day and 75 mg/day, respectively. Objectives: To determine total vitamin C content, L-ascorbic acid and L-dehydroascorbic acid in six samples of orange juice (one nectar, three concentrated juices, one filtrated freshly squeezed juice and one non-filtrated freshly squeezed juice) and to evaluate the nutritional value of these juices as a source of vitamin C. Materials and methods: The oranges and orange juices were acquired in local supermarkets, and only the edible portion was analyzed. Vitamin C content was determined by a highly precise and accurate High Performance Liquid Chromatography method coupled with a photodiode array detector, previously validated. The total vitamin C content was determined by reducing dehydroascorbic acid to ascorbic acid (adding a reducing agent tris(2-carboxyethyl)phosphine). Results and discussion: Total vitamin C content in the analysed samples varied between 42.5 ± 0.7 and 66.4 ± 0.2 mg/100 g of edible portion, for nectar and concentrated juice, respectively. The highest ascorbic acid value and the lowest dehydroascorbic acid content (60.9 ± 0.3 and 1.3 ± 0.6 mg/100 g of edible portion, respectively) were observed in the concentrated juice. The freshly squeezed juices presented higher vitamin C and ascorbic acid contents than the nectar. Considering an intake of 100 mL of juice, the commercial juices can supply 57% to 88 % of DRI for females and 36% to 61% of DRI for males. With respect to freshly squeezed orange juice, 100 mL can contribute with 66% and 51% of DRI, for females and males, respectively. Conclusions: Taking into account the established DRI, orange juices can be considered a good source of vitamin C. Most of the vitamin C content in the analysed orange juices is due to the presence of L-ascorbic acid, which is the main biologically active form of this vitamin and it is an effective antioxidant. Since orange juice is an important and highly consumed source of vitamin C, and due to the wide range of different types of orange juices available in the market, it is essential to analyse total vitamin C content (L-ascorbic and L-dehydroascorbic).