Drying kinetics and quality attributes analysis of moringa (Moringa oleifera) leaves under distinct drying methods

Abstract

The present work aimed to analyze the drying kinetics and color degradation of moringa leaves in selected drying methods. Also, quantitatively analyze the retention of phytochemicals and antioxidant capacity. Moringa leaves were dried using three methods, namely, freeze‐drying (−42 ± 2°C, 0.024 ± 0.001 mbar), microwave drying (200, 400, and 600 W), and hot air oven drying (55, 65, and 75°C). Drying kinetics revealed that the drying of moringa leaves occurred in the falling rate period, which means the diffusion process controlled the moisture removal from leaves. The color degradation was most minor in freeze‐dried leaves, followed by microwave‐dried leaves at 200 W. The value of total phenolic content was found maximum (57.42 ± 2.49 mg GAE/g dm) under microwave drying at 200 W, while the same was found least in quantity (24.62 ± 1.10 mg GAE/g dm) for samples dried under hot air oven drying at 65°C. A similar pattern was observed for total flavonoid content. The antioxidant capacity of the samples dried in the freeze dryer was highest at 5.94 ± 0.25 mg GAE/g dm. This research revealed that microwave drying at 200 W is best regarding the overall quality attributes of moringa leaves.Practical ApplicationsDrying is one of the essential processes in the food industry, for example, drying is crucial for the production of herbal medicines, nutritional supplements and extracts, leaf‐based culinary ingredients, aroma and essential oils, natural dyes and pigments, etc. It is used to increase the shelf‐life of agricultural produce; it facilitates the transportation and storage of food products. This paper may help in the selection of the drying method and condition for leaves drying to have desired characteristics in the final product like color, bioactive compounds, or antioxidant properties; May help in the trade‐off among quality, time, and cost of the production. Moreover, it may be helpful in the designing of the multi‐mode dryer which may produce superior quality products with great energy efficiency in less time. Which further facilitates the manufacturing of nutritionally rich food products.