Effect of Drying Temperature and Time Using a Solar Thermal Dryer on Moisture Content, Color, and Proximate Properties of Moringa (Moringa oleifera) Leaves

Abstract

Moringa leaves are highly nutritious and are often used as a raw material for various processed products. Drying is a crucial step in preserving the leaves before further processing. Solar thermal dryers are an environmentally friendly drying technology that has the potential to help maintain the color and nutritional stability of Moringa leaves through more controlled drying conditions. This study aims to evaluate the effects of solar thermal drying on the nutritional content and color characteristics of Moringa leaves to support the development of appropriate drying methods for maintaining product quality. The study was conducted using a two-factor split-plot design: temperature (40 ℃, 44 ℃, and 47 ℃) as the main plot and time (3 h, 5 h, and 7 h) as the subplot, yielding nine treatment combinations with three replications. The results showed that the treatment conducted at 44 ℃ for 7 h produced lower moisture content and a better stable color, while the treatment conducted at 40 ℃ for 7 h produced the highest moisture content and the least stable color. Furthermore, the treatment conducted at 44 ℃ for 7 h showed higher dietary fiber, ash and lower moisture content compared with the treatment conducted at 47 ℃ for 7 h while protein, fat and carbohydrate contents were not significantly different between the two treatments. Overall, drying at 44 ℃ for 7 h resulted in lower moisture content, acceptable color characteristics and higher dietary fiber and ash content compared with the other tested conditions.