Valorização da casca de citrinos na obtenção de novos compostos fitoquímicos com propriedades saudáveis e tecnológicas
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2017-08-30
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Os frutos cítricos encontram-se amplamente incluídos na dieta Mediterrânica devido, não só às suas propriedades sensoriais mas também ao seu conteúdo em compostos bioativos (nutrientes e não nutrientes). Além do seu consumo em fresco, grande parte da produção de citrinos destina-se ao aproveitamento agro-industrial destes frutos, especialmente em relação ao desenvolvimento de bebidas. Esta atividade industrial está associada à produção de uma grande quantidade de resíduos orgânicos. Assim, depois da extração do sumo, 50% do peso do fruto (15,6 milhões de toneladas a nível mundial) corresponde a resíduos e representa um problema para o meio ambiente e para a sustentabilidade e competitividade das indústrias envolvidas. Estes resíduos são atualmente subutilizados, mas tal como o fruto fresco, também são uma potencial fonte de compostos bioativos.
De entre os compostos bioativos presentes nestes resíduos, a presença de elevadas concentrações de flavanonas pode permitir a sua valorização pela indústria alimentar, no desenvolvimento de produtos de valor acrescentado.
Um dos objetivos deste trabalho visou otimizar as condições de extração de compostos bioativos de cascas de citrinos. Assim, foram utilizadas cascas de laranja (Citrus sinensis) e toranja (Citrus paradisi) tendo sido efetuadas extrações com solvente etanólico do material liofilizado. As condições de extração foram otimizadas relativamente ao efeito da agitação, da razão volume de extratante/massa de amostra, número de extrações e da temperatura na eficiência do processo. Posteriormente, as amostras foram concentradas, e parte delas foram submetidas a purificações adicionais mediante extração em fase solida.
Os extratos obtidos foram analisados mediante testes colorimétricos em relação ao seu conteúdo em fenóis totais, flavonoides, orto-difenois, e foi ainda avaliada a sua capacidade antiradicalar pelos métodos de ABTS e DPPH. Os dados obtidos permitiram determinar a eficiência relativa das diferentes condições de preparação de extratos polifenólicos das cascas dos citrinos selecionados.
Foram observadas diferenças significativas entre os vários métodos de extração usados, tendo-se verificado que a etapa de purificação provocou uma perda de compostos com atividade antiradicalar. Os dados obtidos, permitiram ainda concluir que o método de
extração numa razão de 64 mL de solvente para 2 gramas de amostra à temperatura ambiente e com uma única extração, revelou ser o mais adequado para a extração de compostos bioativos desta matriz alimentar.
O isolamento da hesperidina presente de forma maioritária na casca de citrinos foi obtida num rendimento de 48%, e com ponto de fusão de 255,0-259,2 ºC. Foi possível a sua caracterização inequívoca através da análise de espectros uni e bidimensionais de ressonância magnética nuclear.
A conversão da hesperidina na respetiva calcona foi confirmada através da análise por espectroscopia de infravermelho com transformada de Fourier.
Citrus fruits are widely included in the Mediterranean diet due to, not only to their sensory properties, but also to their content in bioactive compounds (nutrients and no nutrients). Besides, its fresh consumption, much of the production of these fruits is applied into the agro-industry, especially for the development of beverages. This industrial activity is associated with the production of a large amounts of organic wastes. In this connection, after juice extraction, up to 50% of the plant material (15.6 million tonnes worldwide) becomes into residues that represent a problem for the environment in the local area, jeopardizing the sustainability and competitiveness of the industries concerned. These residues are currently underutilized, but similarly to what happens in fresh fruits concerning edible parts, constitute a valuable source of bioactive compounds. Among the bioactive phytochemicals present in these residues, the presence of high concentrations of flavanones may allow their valorization by the food industry by implementing their use in the development of added-value products. One of the objectives of this study is to optimize the extraction conditions for obtaining bioactive compounds from citrus peel. For this, orange (Citrus sinensis) and grapefruit (Citrus paradisi) peels were used, and ethanolic solvent extractions were performed. The extraction conditions were optimized regarding the effect of agitation, ratio extractant volume / sample’s mass, number of extractions, and temperature on the efficiency of the process. Subsequently, samples were concentrated and most of them were subjected to additional purification by solid phase extraction. The obtained extracts were analyzed by colorimetric tests, respecting to their content in total phenols, flavonoids, and ortho-diphenols. It was also evaluated their radical scavenging capacity, resorting to the ABTS and DPPH methods. The data obtained allowed to determine the relative efficiency of the different conditions assayed, relative to the obtaining of polyphenolic extracts of citrus peels. The work performd the allowed to state significant differences between the various methods used for extraction of phenolic compounds. In addition, it was noticed that the purification step caused a loss of compounds with antiradical activity. The data obtained allowed to conclude that the optimal extraction method consisted in a ratio of 64 mL solvent / 2 g of dry citrus peel at room temperature. Moreover, a single extraction was demonstrated to be the most efficient for the extraction of bioactive compounds of this food matrix. The isolation of hesperidin present in a major form in the peel of citrus fruits was obtained in a yield of 48% and melting point of 255.0 to 259.2 ° C. its unequivocal characterization was possible by analyzing one-dimensional and two-dimensional nuclear magnetic resonance spectra. The conversion of hesperidin into its respective chalcone was confirmed through infrared Fourier transform analysis.
Citrus fruits are widely included in the Mediterranean diet due to, not only to their sensory properties, but also to their content in bioactive compounds (nutrients and no nutrients). Besides, its fresh consumption, much of the production of these fruits is applied into the agro-industry, especially for the development of beverages. This industrial activity is associated with the production of a large amounts of organic wastes. In this connection, after juice extraction, up to 50% of the plant material (15.6 million tonnes worldwide) becomes into residues that represent a problem for the environment in the local area, jeopardizing the sustainability and competitiveness of the industries concerned. These residues are currently underutilized, but similarly to what happens in fresh fruits concerning edible parts, constitute a valuable source of bioactive compounds. Among the bioactive phytochemicals present in these residues, the presence of high concentrations of flavanones may allow their valorization by the food industry by implementing their use in the development of added-value products. One of the objectives of this study is to optimize the extraction conditions for obtaining bioactive compounds from citrus peel. For this, orange (Citrus sinensis) and grapefruit (Citrus paradisi) peels were used, and ethanolic solvent extractions were performed. The extraction conditions were optimized regarding the effect of agitation, ratio extractant volume / sample’s mass, number of extractions, and temperature on the efficiency of the process. Subsequently, samples were concentrated and most of them were subjected to additional purification by solid phase extraction. The obtained extracts were analyzed by colorimetric tests, respecting to their content in total phenols, flavonoids, and ortho-diphenols. It was also evaluated their radical scavenging capacity, resorting to the ABTS and DPPH methods. The data obtained allowed to determine the relative efficiency of the different conditions assayed, relative to the obtaining of polyphenolic extracts of citrus peels. The work performd the allowed to state significant differences between the various methods used for extraction of phenolic compounds. In addition, it was noticed that the purification step caused a loss of compounds with antiradical activity. The data obtained allowed to conclude that the optimal extraction method consisted in a ratio of 64 mL solvent / 2 g of dry citrus peel at room temperature. Moreover, a single extraction was demonstrated to be the most efficient for the extraction of bioactive compounds of this food matrix. The isolation of hesperidin present in a major form in the peel of citrus fruits was obtained in a yield of 48% and melting point of 255.0 to 259.2 ° C. its unequivocal characterization was possible by analyzing one-dimensional and two-dimensional nuclear magnetic resonance spectra. The conversion of hesperidin into its respective chalcone was confirmed through infrared Fourier transform analysis.
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Dissertação de Mestrado em Biotecnologia e Qualidade Alimentar
Palavras-chave
Subprodutos , Citrinos , Hesperidina , Compostos fenólicos , Compostos bioativos