ISOLATION OF CAFFEINE FROM TEA WASTE USING SUBCRITICAL WATER EXTRACTION

Abstract

ABSTRACT The aim of this study was to investigate the isolation of caffeine from tea waste using subcritical water extraction (SCWE) method. The effect of various operating conditions such as water temperature (100,125,150, 175 and 200C), water flow rate (1, 2 and 4 g/min), mean particle size (0.25, 0.5, 1 and 2 mm) and pressure (20, 30 and 40 bar) on extraction yield and rate were determined. SCWE at 175C, water flow rate of 4 g/min and mean particle size of 0.5 mm was found to be able to recover 0.77% (w/w) of caffeine present in the tea waste within 1.5 h of extraction. In comparison with the SCWE, conventional hot water extraction showed 0.46% (w/w) extraction yield. It was found also that pressure had no effect on extraction yield and rate. A sustainable and environmentally friendly procedure has been used for the Fourier transform infrared determination of caffeine in tea waste extracted samples. PRACTICAL APPLICATIONSSubcritical water extraction (SCWE), as a green solvent, can be used in many different fields of applications. It can be used to extract antioxidant compounds from rosemary plants as well as to extract whitening agents and azo dyes in samples. Additionally, soil can be remediated through SCWE of dioxins. Recently, subcritical water has become of great interest as an alternative solvent for extraction of natural active compounds. In recent years, extraction of flavors, fragrances and antioxidant components from plant materials, and hydrolysis of carbohydrates, vegetable oils and fatty acids have been widely investigated by many researchers. Using subcritical water as a reaction media are some other interesting fields for practical applications.