Effects of Chitosan Films and Temperatures on Shelf Life of Kratom (Mitragyna speciosa (Korth.) Havil) Leaves

Abstract

Kratom is a traditional medicinal plant widely consumed as fresh green leaves. As kratom leaves degrade rapidly after harvesting, preservation is required to prolong the shelf life and quality of the leaves. In this study, the temperatures used to store kratom leaves were 15°C and 25°C (room temperature), and the five levels of chitosan concentration (0.0, 0.5, 1.0, 1.5, and 2.0%) were applied to the leaves before the storage. It was found that the storage of the leaves at 15°C with 0.5% chitosan concentration resulted in a lower weight loss percentage than the storage at 25°C. The storages of kratom leaves at 15, and 25°C showed a significant difference in leaf color (a*, b*, and L*). However, the different concentrations of chitosan applications caused no difference in leaf color change. Regarding the chlorophyll content, it was found that the storage at 15°C with varying concentrations of chitosan resulted in different values of leaf chlorophyll. The values ranged between 20.05 and 26.57 mg/cm2, lower than those of the 25°C storage, which were in the range of 19.44- 34.06 mg/cm2. The results showed that the shelf life period of kratom leaves was associated with low temperature and chitosan application. The storage of kratom leaves at 15°C with 0.5% chitosan extended the shelf life by approximately 15 days longer than the storage at 25 °C. Therefore, it indicates that the effective packaging system to minimize phytochemical changes during the storage period should be studied further.