Drying of star fruit (Averrhoa carambola L.) : development and application of edible coatings added with natural antioxidants for the functional properties conservation

A carambola e fonte de importantes nutrientes como vitaminas, minerais e muitos fitoquimicos que exercem papeis importantes na saude humana. No entanto, o seu elevado conteudo de agua e a interferencia de agentes externos, como oxigenio e microorganismos, tornam esse produto perecivel e de facil deterioracao. O objetivo deste trabalho foi estudar o efeito da formulacao de coberturas comestiveis aditivadas com antioxidantes, aplicadas previamente a secagem, que assegurem a manutencao das propriedades funcionais de carambola em fatias. Na primeira etapa deste trabalho, fatias de carambolas foram revestidas com coberturas de pectina (2% m/m) e acidos citrico (0,5% m/m) e ascorbico (0,5% m/m), com coberturas de alginato (1% m/m) e acidos citrico (0,5% m/m) e ascorbico (0,5% m/m), com coberturas de pectina (2% m/m) e suco de uva (26% m/m) e com coberturas de alginato (1% m/m) e suco de uva (26% m/m), e desidratadas em secador de ar convectivo nas temperaturas de 50, 60 e 70°C, a fim de verificar a influencia da aplicacao das coberturas sobre a cinetica de secagem e sobre o encolhimento das amostras. Na segunda etapa do trabalho, as amostras foram novamente revestidas, secas e entao armazenadas por 21 dias, com temperatura controlada de 35°C, para avaliar suas caracteristicas nutricionais e fisicas. Verificou-se que a aplicacao das coberturas nao influenciou na cinetica de secagem. A manutencao da forca maxima de ruptura foi mais eficaz nas amostras revestidas, e a retencao da cor foi mais eficiente nas amostras cobertas com pectina e acidos. Em relacao as propriedades nutricionais, a aplicacao das coberturas de pectina auxiliou na retencao de carotenoides, vitamina C e polifenoisThe star fruit is a source of important nutrients such as vitamins, minerals and phytochemicals that play many important roles in human health. However, its high water content and the interference of external agents, such as oxygen and microorganisms, make this perishable product and easy to damage. The aim of this work was to study the effect of the formulation of biodegradable coatings added with antioxidants, applied prior to drying to ensure the maintenance of functional properties of star fruit slices. In the first stage of this work, star fruit slices were coated with pectin (2% w / w) and citric acid (0.5% w/w) and ascorbic (0.5% w / w) with coat of alginate (1% w / w) and citric acid (0.5% w / w) and ascorbic (0.5% w/ w) with coat of pectin (2% w / w) and grape juice (26%, w / w) and coated with alginate (1% w / w) and grape juice (26% w / w) and were dried in an air convective dryer at temperatures of 50, 60 and 70 ° C to verify the influence the application of the coating on the kinetics of drying and the shrinkage of the samples. In the second stage of this work, the samples were again coated, dried and then stored for 21 days, at temperatures of 35°C, to evaluate their nutritional and physical characteristics. It was found that the application of the coating did not influence the drying kinetics. The maintaining of the maximum tensile was more effective in samples coated and the color retention was more efficient in samples coated with pectin and acid. In relation to nutritional properties, the application of the coatings of pectin help in the retention of carotenoids, vitamin C and polyphenol