Evaluation of Drying Methods and Leaf Age on the Nutrient Composition of Orange-fleshed Sweetpotato (Ipomoea batatas L.) Leaves

Abstract

Sweetpotato leaves are considered highly nutritious, serving as an excellent source of minerals, vitamins, and other functional phytochemicals. Their tender, tasteful tips make them a versatile vegetable, suitable for daily consumption either fresh or dried. The nutritional composition of leafy vegetables varies significantly based on factors such as leaf age and drying methods, which can impact their overall health benefits. Therefore, this study aimed to determine the effects of leaf age and drying methods on the nutritional content of orange-fleshed sweetpotato leaves. The experiment followed a completely randomized design with a 4 × 3 factorial arrangement, replicated three times. Four levels of leaf age (upper, middle, lower, basal) and three drying methods (sun-, shade-, oven-drying) were applied as treatments. Significant interactions between leaf age and drying methods were observed for ash content, crude protein, fat, neutral detergent fiber (NDF), calcium, magnesium, potassium, phosphorus, zinc, manganese, and copper. Ash, calcium, and magnesium contents increased with leaf age, with the highest ash content recorded in basal leaves dried in the shade, whereas the lowest was found in shade-dried upper leaves. Conversely, crude protein content was higher in shade-dried upper leaves, sun-dried upper leaves, sun-dried middle leaves, and shade-dried middle leaves. The study indicates that the consumption of shade-dried middle and upper leaves can contribute to addressing food security and promoting the intake of nutritious vegetables due to their higher crude protein content and lower sodium levels.