Micronutrient content of selected green leafy vegetables dehydrated using different drying methods

Abstract

North East India being blessed with a variety of natural surroundings, varying climates and seasons has a number of species of edible green leafy vegetables. Green leafy vegetables are highly perishable with shelf-life of only few days owing to higher moisture content. Drying is a simple, user-friendly technique which removes moisture of the product to an extent that increases the shelf life of the product. The present study intends to investigate nutritional and physical characteristics of six commonly consumed greens namely Rumex vesicarius, Hibiscus sabdariffa, Diplazium esculentum, Polygonum microcephalum, Malva verticillata and Pogostemon benghalensis after dehydration by using four different drying methods, i.e. sun drying, shade drying, cabinet dryer drying and microwave oven drying. Time required for dehydration of the greens till crispness was minimum in microwave drying and maximum in shade drying. Among the greens, Rumex vesicarius took maximum time irrespective of all drying methods. Yield obtained after dehydration of 100g of fresh greens was highest in shade drying for all the samples. Rehydration ratio was highest among microwave dried samples and lowest in shade dried samples. Moisture content was highest in shade dried samples. Among the nutritional parameters, total mineral content, iron, calcium, potassium, phosphorous and ascorbic acid content was found highest in cabinet dryer dried samples, followed by microwave dried samples. Among the greens, Polygonum microcephalum contained highest amount of iron (24.28 mg/100g), calcium (763.33 mg/100g) while phosphorous content was highest in Pogostemon benghalensis (466.34 mg/100g) and Diplazium esculentum contained highest potassium content (2175.65 mg/100g) in cabinet dried samples. Thus it can be concluded that the mineral content of all of the selected greens became concentrated after dehydration. These dehydrated leaves have good rehydration capacity for incorporation into various products to reduce micronutrient deficiency.