Impact of Blanching and Drying on the Nutritional and Antibacterial Quality of Moringa oleifera Leaf Powder
Karma Rigyel and Wang Gyeltshen
https://doi.org/10.55925/btagr.26.9110
ABSTRACT
Moringa oleifera leaves are a vital nutritional resource in Bhutan, yet their high perishability necessitates effective post-harvest processing to prevent rapid spoilage and nutrient loss. This study evaluated the effects of various blanching methods (boiling, steaming, and no blanching) and drying techniques (sun, shade, and oven-drying) on the proximate, phytochemical, and antibacterial properties of the resulting leaf powder. Using a 3 x 3 factorial design, the research identified significant interactions between processing treatments. Results indicated that shade-drying consistently outperformed other drying methods in mineral and protein retention. Specifically, boiling combined with shade-drying maximized crude protein and calcium content, whereas steaming with shade-drying was superior for preserving total phenolics and flavonoids. Conversely, boiling led to the greatest reduction in vitamin C and tannins due to thermal leaching. Notably, the combination of steaming and sun-drying yielded the most potent antibacterial activity against Staphylococcus aureus and Escherichia coli. These findings demonstrate that no single processing protocol optimizes all quality parameters simultaneously; instead, methods must be tailored to the intended end-use of the powder. The study concludes that steaming with shade-drying is ideal for maximizing antioxidant and medicinal functionality, while boiling with shade-drying is preferred for enhancing protein-based nutritional security. These results provide actionable processing protocols for smallholder farmers to improve value-added Moringa products and enhance local food security.
Keywords: Antibacterial activity, Blanching methods, Drying techniques, Moringa oleifera, Phytochemical retention