Comprehensive assessment of drying performance, physical characteristics, bioactive compounds, and antioxidant capacity of mallow (Malva verticillata) vegetables: a comparative study of a modified tray dryer and conventional drying methods

Abstract

Drying vegetables in a suitable dryer is an imperative concern in the food-processing sector. To address this issue, a cabinet-type tray dryer has been developed by modifying its design, employing a comprehensive approach ensuring uniform air velocity and temperature in all the trays, and naming it a modified tray dryer (MTD). A comparative analysis of drying performance, physical characteristics, functional attributes, and antioxidant capacity of mallow (Malva verticillata) vegetables dried in MTD and existing three drying methods such as sun, shade, and traditional cabinet drying was accomplished. The performance evaluation study revealed that MTD demonstrated a faster moisture removal capacity and required less drying time compared to other drying methods. Statistical analysis revealed that drying methods had a significant (p<0.05) impact on the physical properties, functional qualities, and bioactive functions of the dried mallow powder (MP). The higher chlorophyll content (27.41±0.84 mg/100 gm of dry matter, DM), total phenol content (15.71±0.95 mg GAE/g DM), and DPPH activity (8.82±0.81 mg TEAC/g DM) were noticed in the mallow vegetable powder dried in MTD than shade, sun and traditional cabinet drying methods. A slightly lower value (statistically insignificant) of ascorbic acid content (9.64±0.78 mg/100 gm DM) and total flavonoid (1.44±0.05 mg QE/g DM) was achieved in contrast to other drying methods. The antioxidant capacity of the analyzed data was lowest for shade drying compared to other drying methods, while MTD exhibited the highest capacity. Therefore, this study might assist in selecting a suitable dryer for drying vegetables. The findings suggest that MTD can be an alternative drying technique as a quicker drying technique and for obtaining better-quality dried products in terms of antioxidant and functional properties than the traditional and existing process of vegetable drying.