CHEMICAL ENGINEERINGTRANSACTIONS VOL. 56, 2017 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Jiří Jaromír Klemeš, Peng Yen Liew, Wai Shin Ho, Jeng Shiun Lim Copyright © 2017, AIDIC ServiziS.r.l., ISBN978-88-95608-47-1; ISSN 2283-9216 Optimisation of Supercritical CO 2 Extraction of Red Colour from Roselle (Hibiscus Sabdariffa Linn.) Calyces Zuhaili Idham* ,a , Hasmida Mohd Nasir a , Mohd Azizi Che Yunus a,b , Lee Nian Yian a , Wong Lee Peng a , Hashim Hassan b , Siti Hamidah Mohd Setapar a,b a Centre of Lipids Engineering and Applied Research, Ibnu Sina Institute for Scientific &Industrial Research, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia b Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia zuhaili@cheme.utm.my Roselle (Hibiscus sabdariffa Linn.) is a local tropical plant widely cultivated in Malaysia. Roselle produces red edible calyces which contain intense red pigments of anthocyanins. Supercritical fluid extraction with carbon dioxide (CO2) is a particularly suitable isolation method for natural materials and gives an alternative to replace the mass usage of non-polar organic solvents in conventional methods. The advantage of using CO2 as solvent is that no organic solvent residual inside the extracted sample since CO2 is in gas form at room temperature. The red colour extract by using CO2 is easier to be separated by decompression and has high recovery percentage. The objective of this research was to optimise the supercritical carbon dioxide (SC-CO2) extraction conditions for obtaining the maximum yield of red colour extract. SC-CO2 extraction of red colour of roselle was performed with ethanol as modifier at the pressures of 8, 10 and 12 MPa, temperatures of 50, 60 and 70 °C while the percentage of modifier flow rates was at 5, 7.5 and 10 %. Full 3 3 factorial design was used to optimise operating conditions for the extraction yield of roselle calyces in SC-CO2.The other parameters were kept constant, such as total flow rate of CO2 and modifier (6 mL/min), ratio of modifier (75 % of ethanol), the average particle size used (350 µm) and extraction regime (70 min). The findings revealed that the extraction yield was significantly influenced by three main effects investigated in this study, with p-value smaller than 0.05. The optimum operating conditions obtained for SC-CO2 extraction of red colour extract were 8.90 MPa, 70 °C, and 9.49 % with predicted percentage yield of 26.73 %. 1. Introduction The adverse health effect caused by artificial colourant is raising global concern, due to the limited availability of local natural colourant. This issue was due to an effort to replace the artificial colourant because of consumer concern and legislative actions such as the ban of FD&C Red 40 and FD&C Red 2 by the Federal Drug Association (Cevallos-Casals and Cisneros-Zevallos, 2003). Many industries prefer the use of artificial colourant due to the high cost of imported natural colourant. The continuously raising of public concern in this problem has stimulated research interest in local plant, the roselle extract, as the new source of natural colourant and as the alternatives to conventional artificial colourant. Roselle (Hibiscus sabdariffa) calyces have a characteristic of deep red colour, which is mainly due to the presence of four anthocyanins including dephinidin 3-sambubioside or hybiscin and cyanidin 3-sambubioside as the major pigments, and delphinidin 3-glucoside and cyanidin 3-glucoside as the minor ones (Wong et al., 2002). The most common use of Roselle calyces is for obtaining aromatic infusions of intense red colour that are traditionally consumed either cool or hot. Roselle extracts are used as natural pigments for foods and beverages as well as for preparing jams, jellies, and concentrates possessing red colour with a characteristic sour taste. The roselle extract is known to possess several health benefits such as wound healing (Builders et al., 2013), antihypertensive (Herrera-Arellano et al., 2004), anticholesterol (Chen et al., 2003) and other pharmacological effects. DOI: 10.3303/CET1756146 Please cite this article as: Idham Z., Nasir H.M., Yunus M.A.C., Lee N.Y., Wong L.P., Hassan H., Setapar S.H.M., 2017, Optimization of supercritical co2 extraction of red colour from roselle (hibiscus sabdariffa linn.) calyces, Chemical Engineering Transactions, 56, 871-876 DOI:10.3303/CET1756146 871