Drying kinetics of moringa oleifera leaves in a solar greenhouse drier

Abstract The nutritional properties and thermal performance analysis of Moringa Oleifera leaves that were dried in a solar greenhouse are presented in this work. Conventional open sun drying takes 8 h to dry the leaves from an initial moisture content of about 73% (w.b.) to 3% (w.b.) in 5 h. The solar drier's average thermal efficiency was estimated to be 12%, which results in a 38% reduction in drying time compared to open sun drying. The variation of exergy efficiency of the solar greenhouse dryer was found to be 0.9%–7.6% during the drying experiments. The drying kinetic studies were performed for the drying of Moringa leaves in the solar greenhouse drier. Six non‐linear regression models were used for evaluating the drying performance and Midilli‐Kucuk model was found to be best describing the drying behavior of moringa leaves in the solar greenhouse drier. Fick's second law was used to calculate the effective moisture diffusivity and was found to be in the range of 3.12 × 10 −11 m 2 /s to 5.48 × 10 −9 m 2 /s. Arrhenius equation was used to calculate the moisture activation energy and it was found to be 31.2 kJ/mol. The nutritional properties of moringa leaves dried in the solar greenhouse drier was compared with open sun‐dried moringa powder and it was found that its nutritional values are substantially higher. Because of the controlled drying conditions, the percentages of calories, protein, fat, carbohydrate, and vitamin‐C in the solar greenhouse‐dried Moringa powder were 12.75%, 8.33%, 9.52%, 11.71%, and 10.67% higher compared to open‐sun‐dried sample. Furthermore, the solar greenhouse dried moringa powder retained its natural color when compared to open sun dried sample.