Date of Publication


Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Subject Categories

Chemical Engineering


Gokongwei College of Engineering


Chemical Engineering

Thesis Advisor

Allan N. Soriano
John D. Tapia
Kathleen B. Aviso

Defense Panel Chair

Lawrence P. Belo

Defense Panel Member

Cynthia F. Madrazo
Nathaniel P. Dugos


Drying is an essential post-harvest process done to preserve the medicinal qualities of medicinal plants. Although the drying process has been advantageous for the preservation of active ingredients in medicinal plants, the improper operation could lead to undesirable changes in appearance, flavor, and a significant loss in active ingredients. With that, the determination of the drying kinetics and characteristics of medicinal plants is essential to establish the appropriate drying conditions. In this study, the drying behavior of Costus igneus (Insulin Plant), Lagerstroemia speciosa (Banaba), and Blumea balsamifera (Sambong) – medicinal plants in the Philippines used in the treatment of diabetes were investigated. The experimental runs were conducted for two trials per plant system at two different inlet air fan settings (30% and 50%), which approximately corresponded to (0.80 and 1.0 m/s) of air velocity, and three different inlet air temperatures (45°C, 50°C, 55°C) using the Armfield UOP8 MKII convective tray dryer, thus having a total of 6 conditions. Among the three plant systems, the Insulin plant had the highest initial moisture content, longest drying time, and lowest drying rate. For all six conditions, all three systems had no constant rate period and only exhibited falling rate period/s. The drying rate for each plant system generally increased with temperature but only up to a certain point, where beyond it the opposite trend occurs. Changes in the morphology during the drying process caused by shrinkage may have led to this behavior. Sambong had the largest drying rate initially but was most affected by shrinkage as evident in the large decrease in its drying rate. Ten thin-layer drying kinetics models were evaluated for all conditions. Demir model was determined to be applicable for all conditions among all plant systems. Wang and Singh model was also found to be applicable for all conditions of banaba while Kaleemullah model for sambong and insulin plant. Effective moisture diffusivity for all conditions of the plant systems was also obtained and within the expected range of to . The activation energy for the plant systems, except Insulin plant dried at 30% fan setting, was within the expected range of 12.32 to 82.93 kJ/mol. Based on the observed variation of effective moisture diffusivity with moisture content, liquid diffusion is the main moisture transport mechanism at the earlier stage of drying, while vapor diffusion takes place at the latter stage of the process.

Abstract Format







Medicinal plants —Drying

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Available for download on Saturday, January 11, 2025