Effect of Temperature on the Color of Natural Dyes Extracted Using Pressurized Hot Water Extraction Method

Problem statement: Traditionally, extraction of natural dyes with boiling method produced only one single tone of colorant/dyes which involved plenty of water in several hours of extraction time. A new modern extraction technique should be introduced especially to textile dyers so that a variety of tone of colorants can be produced in a shorter time with less consumption of water. Approach: This study demonstrated Pressurized Hot Water Extraction (PHWE) as a new technique to extract colorants from a selected plant, i.e., Xylocarpus moluccensis species which can be found abundantly in Peninsular Malaysia. Colorant from the heartwood of Xylocarpus moluccensis was extracted at different elevated temperatures, from 50°C up to 150°C using PHWE technique and the extracts obtained were compared to those obtained via boiling method at 100°C. The color strength of dye extracts was then analyzed using UV-Visible spectrophotometer and Video Spectral Comparator (VSC 5000). The effect of the extraction temperatures on the color of extracts obtained by PHWE was also investigated. Results: Results show that the colorimetric data obtained from VSC reading exhibited the exact tone of colors found in anthraquinone. UV-Visible spectrum also shows that higher absorbance of natural dyes extracted via PHWE compared to those obtained by boiling method. Conclusion: By using PHWE employed at different elevated temperatures, different tones of colorants can be produced from one single source in a shorter time with less consumption of water.