Browsing by Author "Abeysinghe, D. C."

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    Effect of drying methods on the total flavonoid content, total phenolic content and total antioxidant capacity of five plant leaves with potential use in cosmetics
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Gamage, D. G. N. D.; Abeysinghe, D. C.; Wijesekara, R. G. S.; Prathapasinghe, G. A.; Dharmadasa, R. M.; Someya, T.
    Drying is the most common and fundamental method for post-harvest preservation of medicinal plant materials. It allows the quick conservation of medicinal qualities of plant materials in an uncomplicated manner. However, the instability of some flavonoids and phenolic compounds in medicinal plants which exhibit potent antioxidant activity and wide range of pharmacological properties may indicate a sensitivity to different drying treatments. In this sense, it is important to determine the factors that can preserve these crucial bioactive compounds of plant materials during the drying process. Therefore, the objective of the present study was to determine the effect of hot air oven drying, solar drying and shade drying on bioactive ingredients of five cosmetic potential plant leaves. Leaves of Centella Asiatica (L.) Urb., Senna alata (L.) Roxb., Justicia adhatoda L., Ocimum tenuiflorum L., Hibiscus rosa-sinensis L. were dried to a constant weight using shade drier at 30-35 °C, solar drier at 30-40 °C and hot air oven at 40 °C. Folin- Ciocalteau method, aluminum chloride colorimetric assay and phosphomolybdate assay were employed to analyse the total phenolic content, total flavonoid content and total antioxidant capacity of ethanolic extracts of leaves respectively. All assays were performed in triplicate. Results showed that significantly higher flavonoid content, phenolic content and antioxidant capacity of solar dried leaves of O. tenuiflorum and H. rosa-sinensis in comparison with hot air oven drying and shade dried samples. Solar dried C. asiatica and S. alata leaves showed high flavonoid content and antioxidant capacity while the phenolic content was high in shade dried leaves of S. alata and oven dried leaves of C. asiatica respectively. In contrast, J. adhatoda showed the maximum flavonoid content in shade drying samples, the highest phenolic content in solar dried leaves and the maximum antioxidant capacity in oven dried leaves. Moreover, there were no significant differences (p > 0.05) among drying methods in terms of antioxidant capacity and phenolic content of J. adhatoda. and antioxidant capacity of C. asiatica. Thus, it can be concluded that, not only drying temperature and duration but also the plant species and types of metabolites present in plant materials determine the effect of drying method on bioactive compounds. Finally, solar drying of medicinal plant materials using solar drier would be an economical, efficient and effective drying method for preserving bioactive compounds present in leaves of above-mentioned plant materials
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    Fabrication, optimization and evaluation of an indirect heated forced air circulation type solar dryer for drying of Pogostemon heyneanus Benth
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Amadoru, I. J.; Abeysinghe, D. C.; Gunathilaka, H. A. W. S.; Dharmadasa, R. M.
    Pogostemonheyneanus Benth. is an aromatic plant cultivated for extracting patchouli oil which is largely used in perfumery, pharmaceutical and food industries. The oil is extracted via steam distillation of shade dried leaves. The weaknesses in shade drying have highlighted the demand in innovation of an environmentally sound drying technique. The focus of the present study was to fabricate an indirect heated forced air circulation type solar dryer and evaluate its performances pertaining drying of patchouli herbage. Three different spreading levels; 0.1, 0.2 and 0.3 kg per square foot were used. In each trial, the same amount of fresh material as in the dryer was shade dried as the control. Drying conditions; temperature, humidity and light intensity and moisture loss were measured at the top, middle and bottom positions of the dryer and in the control at three-hour interval until the herb wet basis moisture content reached less than 15%. At the end of drying, essential oil was distilled using Clevenger arm apparatus. Finally, oil compositions were analyzed using gas chromatography mass spectrometry (GC-MS). All the drying conditions closely followed light intensity patterns. Oil contents of top and bottom trays were always lower than that of the middle as they were directly exposed to solar radiation. Spreading rate of 0.2 kg per square foot had the best oil content (1.32 %) and there were no significant differences in oil contents among top, middle and bottom trays. To dry the same quantity of material as in the dryer with 0.2 kg per square foot of spread, the time requirement for shade drying (control) was almost double (63 hours) as that for solar drying (30 hours) and shade drying had less oil content (1.28 %). Further, patchouli alcohol (23.77%) and α-guanene (3.73%) were found to be slightly increased under solar drying while α – patchoulene (1.47 %) and seychellene (2.58 %) were found to be slightly increased under shade drying. However, the effect of solar and shade drying techniques on overall oil composition was almost identical. Thus, the solar dryer under optimized conditions could be recommended over shade drying in terms of drying time, oil content and space utilization