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Total antioxidant capacity tests on wine and teas
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Resumo(s)
Atualmente, os antioxidantes são tidos como compostos extremamente importantes e bioativos devido aos seus muitos benefícios comprovados para a saúde. Geralmente encontrados em vegetais e frutas, os polifenóis são um grupo complexo de moléculas às quais a ciência atribui propriedades antioxidantes. O desejo da descoberta da verdadeira capacidade antioxidante de vários produtos comestíveis tem crescido com o aumento da incidência de problemas de saúde complexos relacionados com a poluição e acumulação patológica de radicais livres. Neste trabalho experimental, a capacidade antioxidante de diferentes vinhos e chás, cinco e seis variedades respetivamente, é avaliada pelo método da quimioluminescência TRAP (Parâmetro antioxidante de captura total de radicais). A decomposição do ABAP [2,2’Azobis(2-methylpropionamidine)] produz radicais livres que interagem com o luminol, levando à quimioluminescência por este induzida. A luminescência formada é então extinta pela adição de amostras de antioxidantes ao meio reacional que suprimem o fenómeno de emissão de luz por um certo período (τlag). O Trolox, um análogo do tocoferol solúvel em água, é o inibidor de referência comumente empregue em ensaios de determinação antioxidante sendo portanto empregue como padrão. Os tempos de indução obtidos foram avaliados considerando a sua proporcionalidade em relação à concentração antioxidante e ao poder de neutralização radicalar dos compostos antioxidantes presentes, resultando na determinação da capacidade antioxidante total das amostras. As atividades antioxidantes das amostras foram expressas em equivalentes de Trolox micromolares. O vinho mostrou uma atividade antioxidante significativamente mais alta quando comparado ao chá de aproximadamente 82,2%. O melhor resultado entre os chás, pertencente ao sencha, está ainda aproximadamente 25% abaixo da menor atividade antioxidante obtida para o vinho. Foram discutidas como as variedades das uvas, tempo e processos de maturação podem afetar a capacidade antioxidante dos vinhos, bem como aspetos relativos ao tratamento das safras de chá, exposição a reações de fermentação e métodos de extração. A capacidade antioxidante total avaliada pela metodologia TRAP diminuiu na ordem: Syrah>Sangiovese>Cabernet Sauvignon>Cabernet Sauvignon + Merlot>Cascinello>sencha> bancha>verde>matcha> preto>rooibos. Foi também verificado o efeito do armazenamento do chá na perda de atividade antioxidante, na qual o matcha demonstrou ser o menos afetado entre as amostras.
Nowadays, antioxidants are taken as extremely important and bioactive compounds due to their many proven health benefits. Generally found in vegetables and fruits, polyphenols are a complex group of molecules to whom science has attributed antioxidant properties. The desire to uncover the true antioxidant capacity of multiple edible products has been growing with arising complex health issues related to pollution and ultimately associated with free radical’s pathological accumulation. In this experimental work, the antioxidant capacity of different wines and teas, five and six varieties, respectively, is assessed using the chemiluminescence method of total radical trapping antioxidant parameter (TRAP). ABAP [2,2’-Azobis (2methylpropionamidine)] decomposition produces free radicals that will interact with luminol, leading to luminol induced chemiluminescence. The luminescence formed is then quenched by the addition of antioxidant samples into the reaction medium which will supress the light emission phenomenon for a certain amount of time (τlag). Trolox, a water-soluble analogue of tocopherol has been reported as the gold standard reference inhibitor commonly employed in antioxidant determination assays and as such it was used as standard. The induction times obtained were evaluated regarding their proportionality towards antioxidant concentration and radical neutralization power from the antioxidant pool of compounds, resulting in the determination of the total antioxidant capacity of the given samples. The antioxidant activities of the samples were expressed as micromolar Trolox equivalents. Wine showed a significant higher antioxidant activity compared to tea of roughly 82,2%. The highest result belonging to sencha tea was still approximately 25% below the lowest wine antioxidant activity tested. Wine grapes cultivar varieties, maturation time and processes affecting antioxidant capacity were discussed as well as tea plant cultivars treatment aspects, subjection to fermentation reactions and extraction methods. Total antioxidant capacity assessed with TRAP methodology decreased in the order: Syrah > Sangiovese > Cabernet Sauvignon > Cabernet Sauvignon + Merlot > Cascinello > sencha > bancha > green > matcha > black > rooibos. Brewed tea storage effect on antioxidant activity loss was also verified in which matcha demonstrated to be the less affected among tea samples.
Nowadays, antioxidants are taken as extremely important and bioactive compounds due to their many proven health benefits. Generally found in vegetables and fruits, polyphenols are a complex group of molecules to whom science has attributed antioxidant properties. The desire to uncover the true antioxidant capacity of multiple edible products has been growing with arising complex health issues related to pollution and ultimately associated with free radical’s pathological accumulation. In this experimental work, the antioxidant capacity of different wines and teas, five and six varieties, respectively, is assessed using the chemiluminescence method of total radical trapping antioxidant parameter (TRAP). ABAP [2,2’-Azobis (2methylpropionamidine)] decomposition produces free radicals that will interact with luminol, leading to luminol induced chemiluminescence. The luminescence formed is then quenched by the addition of antioxidant samples into the reaction medium which will supress the light emission phenomenon for a certain amount of time (τlag). Trolox, a water-soluble analogue of tocopherol has been reported as the gold standard reference inhibitor commonly employed in antioxidant determination assays and as such it was used as standard. The induction times obtained were evaluated regarding their proportionality towards antioxidant concentration and radical neutralization power from the antioxidant pool of compounds, resulting in the determination of the total antioxidant capacity of the given samples. The antioxidant activities of the samples were expressed as micromolar Trolox equivalents. Wine showed a significant higher antioxidant activity compared to tea of roughly 82,2%. The highest result belonging to sencha tea was still approximately 25% below the lowest wine antioxidant activity tested. Wine grapes cultivar varieties, maturation time and processes affecting antioxidant capacity were discussed as well as tea plant cultivars treatment aspects, subjection to fermentation reactions and extraction methods. Total antioxidant capacity assessed with TRAP methodology decreased in the order: Syrah > Sangiovese > Cabernet Sauvignon > Cabernet Sauvignon + Merlot > Cascinello > sencha > bancha > green > matcha > black > rooibos. Brewed tea storage effect on antioxidant activity loss was also verified in which matcha demonstrated to be the less affected among tea samples.
Descrição
Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2019
Palavras-chave
Antioxidant capacity TRAP Wine Tea Chemiluminescence Mestrado Integrado - 2019