RESUMO
Edible flowers (EFs) are currently consumed as fresh products, but their shelf life can be extended by a suitable drying technique, avoiding the loss of visual quality and valuable nutraceutical properties. Begonia cucullata Willd is a common ornamental bedding plant, and its leaves and flowers are edible. In this work, B. cucullata red flowers were freeze-dried (FD) and hot-air dried (HAD) at different temperatures. To the best of our knowledge, our study is the first one comparing different drying methodologies and different temperatures involving sensory characterization of EFs; therefore, a codified method for the description of the sensory profile of both fresh and dried B. cucullata was developed and validated. Phytochemical analyses highlighted the better preservation of antioxidant compounds (polyphenols, flavonoids and anthocyanins) for flowers dried at 60-70 °C. Visual quality was strongly affected by the drying treatments; in particular the color of the HAD samples significantly turned darker, whereas the FD samples exhibited a marked loss of pigmentation. Although all drying conditions led to a reduction in the hedonic indices if compared with fresh flowers, the best results in terms of organoleptic properties were obtained when the drying temperature was set to 60 or 70 °C.
RESUMO
ABSTRACT: The white mulberry leaves are typically available on the market in dried or encapsulated form. It was assumed in the study that appropriate drying of leaves of the white mulberry is significant for obtaining intermediate products with high content of compounds having anti-oxidative activity. The purpose of the study was to determine the influence of the temperature of mulberry leaves air drying on the content of phenolic acids and flavonols. It has been determined that the content of these compounds in the leaves depended on the drying temperature. Drying at 60 °C favored release of phenolic acids and flavonols from complexes and/or formation of new compounds. Their total content was 22% higher than in leaves dried at 30 °C. Drying at 90 °C reduced the phenolic acid and flavonol content by 24%. The most favorable drying temperature was 60 °C.
RESUMO: As folhas da amoreira branca estão normalmente disponíveis no mercado em forma seca ou encapsulada. Assumiu-se no estudo que a secagem adequada das folhas da amora branca é importante para a obtenção de produtos intermediários com alto teor de compostos com atividade antioxidante. O objetivo do estudo foi determinar a influência da temperatura de secagem de ar de folhas de amoreira sobre o teor de ácidos fenólicos e flavonóis. Foi determinado que o conteúdo destes compostos nas folhas dependia da temperatura de secagem. Secagem a 60 °C favoreceu a liberação de ácidos fenólicos e flavonóis a partir de complexos e / ou formação de novos compostos. Seu teor total foi 22% superior ao das folhas secas a 30 °C. A secagem a 90 °C reduziu o teor de ácido fenólico e flavonol em 24%. A temperatura de secagem mais favorável foi de 60 °C.
