Extraction and fractionation of alkylresorcinols from triticale bran by two-step supercritical carbon dioxide Yasantha Athukorala, F.S. Hosseinian, G. Mazza * Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, British Columbia, V0H 1Z0, Canada article info Article history: Received 9 January 2009 Received in revised form 30 October 2009 Accepted 22 November 2009 Keywords: Triticale Wheat Alkylresorcinol Lipids Supercritical carbon dioxide Fractionation abstract Bran from triticale cultivars Ultima and Pronghorn and Canadian Prairie Spring (CPS) wheat were frac- tionated using a two-step sequential supercritical carbon dioxide (SC–CO 2 ) extraction technique with and without ethanol to selectively extract and enrich high-value alkylresorcinols (ARs). Pure SC–CO 2 (70  C; flow rate 25 g/min; pressure 35 MPa), was used for the first extraction step. The non-polar lipids yield ranged from 3.08 to 3.26 g/100 g and they were composed mainly of C18:2 (33–41 g/100 g), C18:1 (15–21 g/100 g), C16:0 (15–19 g/100 g), and C18:3 (4–5 g/100 g) fattyacids. The second extraction step, performed on the bran remaining after the first extraction, was carried out with SC–CO 2 plus 0.5 mL/min ethanol (70  C; flow rate 5 g/min; pressure 35 MPa). The resulting total polar lipid yield of bran samples ranged between 0.62 and 0.86 g/100 g and the main compounds present in the polar lipids were ARs. The total AR contents of triticale cv Ultima, wheat, and triticale cv Pronghorn were 70, 68 and 36 mg/100 g, respectively. Saturated and unsaturated AR homologues of C15:0, C17:0, C19:0, C19:1, C21:0, C21:1, C23:0 and C25:0 were detected in all samples. Over 98% of the triticale ARs and over 95% of the wheat ARs were extracted under the SC–CO 2 conditions used. Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved. 1. Introduction Resorcinolic lipids, alternatively referred to as alkylresorcinols (ARs) or 5-alkylresorcinols, are an important class of secondary metabolites that occur in bacteria, algae, mosses, fungi, animals and higher plants (Kozubek & Tyman, 1999). Alkylresorcinols are involved in multiple biological activities, including antimicrobial (Reiss, 1989), anti-parasitic (Kozubek & Tyman, 1999; Suresh & Raj, 1990), antioxidant (H1adyszowski, Zubik, & Kozubek, 1998) and anti-mutagenic activities (Kenji et al., 2003; Gasiorowski, Brokos, Kulma, Ogorza1ek, & Sko ´ rkowska, 2001). Dietary ARs also regulate g-tocopherol and cholesterol levels in rat livers (Ross, Yan, et al., 2004). A significant biological role of ARs is the direct modulation of enzymatic activities (Hengtrakul, Mathias, & Lorenz, 1991b). The potential health benefits and biological activities of ARs have generated significant scientific interest. Naturally occurring AR compounds have been found in eleven families of higher plants, including the grass family (Poaceae, also called Gramineae) (Kozubek & Tyman, 1999), which provides more than half the calories consumed by humans. Among the cereal grass species, the bran fractions of rye, wheat, triticale and barley contain high levels of saturated AR homologues, including C15:0, C17:0, C19:0, C21:0, C23:0 and C25:0. ARs have been reported to be present in the bran of wheat (32–101 mg/100 g), rye (36–320 mg/ 100 g), triticale (58–163 mg/100 g) and barley (4–50 mg/100 g) (Ross et al., 2003) and are present in very low amounts in maize (Gembeh, Brown, Grimm, & Cleveland, 2001) and millet (Heng- trakul, Lorenz, & Mathias, 1991a). GC analysis of hand-dissected fractions of wheat, barley and rye kernels showed that over 99% of the total ARs are contained in an intermediate layer of the cary- opsis, which includes the hyaline layer, testa and inner pericarp (Landberg, Eldin, Marttila, Rouau, & Aman, 2008). Cereal ARs have traditionally been extracted using organic solvents, particularly acetone and ethyl acetate and require lengthy extraction procedures (e.g. a 24 h extraction period performed three times, totaling 72 h). The amount of solvent used has varied, but the ratios of the sample-to-organic solvent have been mostly between 0.02 and 0.03 (w/v) (Ross, Eldin, & Aman, 2004). There are several disadvantages associated with organic solvent extraction techniques, including long extraction times, toxic waste generation and a lack of selectivity. Additionally, the public has become increasingly sensitive to food security, safety and quality (Ho, Cacace, & Mazza, 2007). Supercritical CO 2 (SC–CO 2 ) extraction can be used as an alternative to organic-solvent extraction. The gas-like properties of SC–CO 2 , such as its very low surface tension and viscosity, allow the solvent to penetrate into the substrate, whereas * Corresponding author. Tel.: þ1 250 494 6376; fax: þ1 250 494 0755. E-mail address: Giuseppe.Mazza@agr.gc.ca (G. Mazza). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$ – see front matter Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2009.11.008 LWT - Food Science and Technology 43 (2010) 660–665