J. of Supercritical Fluids 39 (2007) 323–329 Supercritical fluid extraction of carotenoids and chlorophyll a from Synechococcus sp. M.D. Mac´ ıas-S´ anchez a,∗ , C. Mantell a , M. Rodr´ ıguez a , E. Mart´ ınez de la Ossa a , L.M. Lubi´ an b , O. Montero b a Department of Chemical Engineering, Food Technology and Environmental Technologies, Science Faculty, University of Cadiz, Avda. Rep´ ublica Saharaui, s/n, 11510 Puerto Real (C´ adiz), Spain b Institute for Marine Sciences of Andalucia (CSIC), Avda. Rep´ ublica Saharaui, 2, 11510 Puerto Real (C ´ adiz), Spain Received 20 June 2005; received in revised form 24 February 2006; accepted 6 March 2006 Abstract Supercritical carbon dioxide extraction of carotenoids and chlorophylls is an alternative to solvent extraction because it provides a high-speed extraction process with a simple purification stage. In the study described here, carotenoid and chlorophyll extraction with supercritical CO 2 was explored using dry biomass from a marine cyanobacterium Synechococcus sp. as the raw material. The operation conditions were as follows: pressures of 100, 200, 300, 400 and 500 bar, temperatures of 40 , 50 and 60 ◦ C. Analysis of the extracts was performed by measuring the absorbance and by using an empirical correlation. The results demonstrate that the highest extraction yield of total carotenoids is obtained operating at a pressure of 300 bar and a temperature of 50 ◦ C. The most appropriate operating conditions to obtain the best yield in the extraction of chlorophyll a are 500 bar and 60 ◦ C. The highest carotenoids/chlorophylls (Carot/Chlor) ratio is obtained at 200 bar and 60 ◦ C. Under these operating conditions a higher selectivity is obtained and this should facilitate the separation and purification of the two extracted pigments. © 2006 Elsevier B.V. All rights reserved. Keywords: Supercritical fluid extraction; Carotenoids; Chlorophyll a; Synechococcus sp.; Microalgae 1. Introduction The development of increasingly restrictive legislation con- cerning the origin of preservatives used in the production of alimentary products, along with the growing demand by con- sumers for substances from natural sources, has meant that the preparation of products by means of microalgae is a viable alter- native to chemical synthesis [1,2]. On the other hand, methods of extraction of pigments involving conventional organic solvents, besides being limited by legislation, require several purification stages [3]. The production of carotenoids from microalgae constitutes a topic of great scientific and commercial importance within the alimentary and aquaculture fields [4]. The main interest in the use of carotenoids lies in the advantage that it is not affected, as ∗ Corresponding author. Tel.: +34 956016579; fax: +34 956016411. E-mail address: dolores.macias@uca.es (M.D. Mac´ ıas-S´ anchez). other colourings are, by the presence of ascorbic acid, heating and freezing. Furthermore, this compound has a high colouring capacity that is sensitive even at levels of parts for million as a food colouring. Legislation allows the use of this colouring in processed foods such as margarine, cheese, ham and gelatine [5]. As far as chlorophylls in food technology are concerned, stud- ies usually focus on avoiding the degradation of this material during processing and storage so that it is present in a natural form in food [6]. The use of this compound is authorized in food applications such as colouring in the manufacture of cold drinks and ice creams among others [7,8]. The application of the extraction technique with supercritical carbon dioxide to the production of alimentary preservatives has been widely studied in recent years due to the clear advantages of carbon dioxide as a solvent—these advantages include low toxicity, low cost and ease of separation of the extracted product [9–11]. The extraction of carotenoids by this technique repre- sents an alternative to the conventional extraction method as the 0896-8446/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.supflu.2006.03.008