Colour, nutritional composition and antioxidant properties of dehydrated carrot (Daucus carota var. sativus) using solar drying techniques and pretreatments

Abstract

Carrot is a seasonal perishable tuberous root vegetable which presents a preservation challenge owing to its elevated moisture content. Recently, carrot processing has received more attention because of its many health-promoting qualities and the reduction of postharvest losses in a cost-effective safe way. This study was designed to sort out the effective solar drying technique including pre-treatment that would retain the color and quality characteristics of dehydrated carrot. Carrot slices were subjected to dry using open sun drying (D1), solar drying long chimney (D2), solar drying short chimney (D3) and box solar drying (D4) techniques with the pretreatments of ascorbic acid 1 % (C3), citric acid 5 % (C4), potassium metabisulfite 1 % (C5) and potassium sodium tartrate 0.3 % (C6) before drying. Drying characteristics, nutritional attributes, phytochemicals and antioxidant of the dehydrated carrot samples were compared with the fresh sample and untreated (control) sample. Results showed that D4 was a good drying method to preserve nutritional quality with good appearance. Among the pretreatments, C5 and C4 resulted improved nutritional quality retention, enhanced visual acceptability and enriched antioxidant activities. PCA (Principal Component Analysis) and correlation matrix revealed that D4 with C5 retained the maximum amount of vitamin, minerals, total phenolic content, antioxidant and admirable dehydrated carrot color by inactivating enzymatic reaction. Therefore, box solar drying with potassium metabisulfite pretreatment would be very promising for functional carrot drying retaining acceptable color and nutrition composition.