Resumo No presente trabalho pretendeu-se avaliar o efeito da secagem por convecção com ar quente, secagem à sombra e liofilização sobre compostos bioactivos e actividade antioxidante de pétalas de centáurea, bem como em algumas propriedades físico-químicas. Todas as amostras desidratadas apresentaram uma aparência diferente das frescas, menor acidez titulável e menores teores de carotenóides e taninos hidrolisáveis. Por outro lado, as amostras secas apresentaram uma maior actividade antioxidante. Entre os métodos de secagem, a secagem à sombra apresentou os maiores valores de antocianinas monoméricas, flavonóides, taninos hidrolisáveis, capacidade redutora total e actividade antioxidante. Pelo contrário, as maiores perdas foram observadas com ar quente. Assim, a secagem à sombra é um processo bastante promissor que deve ser considerado como um método adequado para desidratar pétalas de centáurea.

Abstract The present study aimed to evaluate the effects of hot-air convective drying, shade drying and freeze-drying on the bioactive compounds and antioxidant activity of Centaurea ( Centaurea cyanus L.) petals, as well as on several of their physicochemical properties. All the dried samples showed different appearances as compared to fresh petals, with lower titratable acidity, lower carotenoids and hydrolysable tannins contents, and greater antioxidant activity. Of the drying methods, shade drying presented the highest values for monomeric anthocyanins, flavonoids, hydrolysable tannins, total reducing capacity and antioxidant activity. By contrast, greater losses were observed as a result of hot-air convective drying. Thus shade drying is a highly promising process that should be considered as a suitable drying method for Centaurea petals.

As flores comestíveis têm sido usadas na culinária de diversos países, tendo hoje em dia, o seu uso despertado a atenção com o intuito de melhorar a aparência, sabor e valor estético de pratos, aspetos que o consumidor aprecia e valoriza. No entanto, os consumidores também exigem alimentos com propriedades benéficas para a saúde, procurando produtos com qualidade nutricional interessante. Nesse sentido, o presente documento pretende abordar a composição nutricional de algumas flores comestíveis, incluindo os macro e os micronutrientes, bem como alguns compostos bioativos que demonstram o valor e potencial das flores comestíveis.

Edible flowers have been used in the gastronomy of several countries. Nowadays, they are attracting increasing attention worldwide in order to improve the appearance, taste and aesthetic value of dishes, aspects that the consumer appreciates and valorizes. However, consumers also demand foods with beneficial properties for their health, looking for products with interesting nutritional characteristics. In this sense, this document revises the nutritional composition of some edible flowers, including macro- and micronutrients, as well as bioactive compounds, in order to show their value and potential.

Coffee is widely consumed and appreciated all over the world, both for their stimulating effect and organoleptic characteristics. Due to its complex chemical composition and the factors involving brews preparation, the consumer is exposed to a wide range of chemical compounds. Several investigations aimed to clarify and understand coffee health effects. There is no evidence that moderate consumption could be harmful. On the contrary, some benefits and possible protective effects against several pathologies have been suggested. This review compiles the main conclusions related with the "coffee and health" topic, reporting, when possible, the chemicals involved.