Miniprocessamento e secagem de folhas e caule do coentro (Coriandrum sativum) var. verdão para a produção de extrato seco.

Abstract

The coriander it is a season vegetable of spread out use in Brazil and the world, being used in the food industries and druggist. However, this vegetable is fairly perishable, because of the high moisture content, needing immediate conservation. In this work it was studied the drying kinetics of coriander leaves and stems in natura, with and without blanching as pretreatment, in the temperatures of 50, 60, 70 and 80°C and air flow of 1.0 and 1.5 m-s"1, being applied three mathematical models to represent the drying curves. Also it was assessed the temperatures effect, as well as the blanching effect, on the final quality of the dry extract of the leaves and stems, through the determinations of ascorbic acid, crude protein, total chlorophyll and color parameters, represented by, luminosity, chroma and hue and, even, the adsorption isotherms, in the temperatures of 20, 30, 40 and 50°C, where they had been applied five mathematical models. With respect of the drying, Midilli and Kucuk model is the best model to represent the drying curves, for the leaves and stems, blanched and unblached, with R over 99% and lowest mean square deviation. The blanching applied to leaves it does not increase the drying velocity, however reverse effect is observed on the stem drying. The adsorption isotherms of coriander leaves and stems well are represented by the Smith and Peleg models, with R2 greater than 99% and mean relative deviation lesser than 6%. As regards the temperature effect on the final quality of dry extract, it is verified the greatest lost in ascorbic acid and chlorophyll content, for the dehydrated leaves and stems at 70 and 80°C. The crude protein content, for the leaves, shows the greatest reduction at 80°C (14.77%), not having been statistics difference to the stem between the studied temperatures. The ascorbic acid and crude protein content for leaves and stems dehydrated with blanching show the greatest reduction for these components and, the lowest reduction for the chlorophyll. The color of the dehydrated leaves with blanching it is degraded more quickly than the stem.