chemical engineering research and design 89 (2011) 318–327 Contents lists available at ScienceDirect Chemical Engineering Research and Design journal homepage: www.elsevier.com/locate/cherd Application of organic solvent nanofiltration for concentration of antioxidant extracts of rosemary (Rosmarinus officiallis L.) D. Peshev a,∗ , L.G. Peeva b , G. Peev a , I.I.R. Baptista b , A.T. Boam c a Department of Chemical Engineering, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria b Department of Chemical Engineering and Chemical Technology, Imperial College London, London SW7 2AZ, UK c Membrane Extraction Technology Ltd., London HA0 4PE, UK abstract The present investigation revealed the potential benefits of nanofiltration application in herbal extracts processing. Nanofiltrations of modelling solution of caffeic and rosmarinic acid in ethanol and ethanolic rosemary extract were carried out in a laboratory cross-flow system. Duramem TM 200 nanofiltration membrane was selected based on screening experiments. The experimental data and model predictions demonstrated the efficacy of a semi-batch cross-flow diafiltration process for concentration of fresh rosemary extracts. The observed absence of significant loss of antioxidant capacity in the retentate during the process and the degree of extract concentration achieved may allow retentate direct application as preservative and functional ingredient in the foods, cosmetics, neutraceuticals and medicines. The capability of the selected membrane to separate monophenolic acids from higher molecular weight antioxidant compounds in the extracts was also discussed. The dry solids content in the permeate was found sufficiently low as to permit its direct re-use in the extraction process thus bringing additional economical benefits. © 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Keywords: Organic solvent nanofiltration; Rosemary extract; Antioxidant activity 1. Introduction In the last decade there has been an increased interest in the development of new techniques for detection, extrac- tion and separation of natural compounds with biological activity and potential benefits for human health (Naczak and Shahidi, 2006; Cuvelier et al., 1996). Spices and aromatic herbs have been a particular object of this interest due to their high content of vitamins, flavonoids, terpenoids, carotenoids, phytoestrogens, minerals, etc., resulting in a strong antioxi- dant, antimicrobial and anti-inflammatory activity. The main challenge in this direction is the selection of suitable herbs and development of technologies for production of natural antioxidants that can be used as preservatives and func- Abbreviations: AU, absorption unit; BHT, 3,5-di-tert-4-butylhydroxytoluene; CA, caffeic acid; DM, Duramem TM ; DPPH • , 2,2-diphenyl- 1-pikryl-hidrazyl; DS, dry solids; MW, molecular weight; MWCO, molecular weight cut-off; OSN (SRNF), organic solvent nanofiltration (solvent resistant nanofiltration); RA, rosmarinic acid; RE, rosemary extract; SR, solid residue. ∗ Corresponding author. Tel.: +359 2 8163293; fax: +359 2 8685488. E-mail addresses: d.peshev@uctm.edu (D. Peshev), l.peeva@imperial.ac.uk (L.G. Peeva), georgiapeev@gmail.com (G. Peev), i.baptista@imperial.ac.uk (I.I.R. Baptista), atb@membrane-extraction-technology.com (A.T. Boam). Received 19 December 2009; Received in revised form 7 June 2010; Accepted 2 July 2010 tional ingredients in the foods, cosmetics, neutraceuticals and medicines. This challenge also answers increasing con- sumers’ demand for “natural” foods (Hernandez-Hernandez et al., 2009; Riznar et al., 2006) and overcomes the tighter restrictions for use of synthetic products. The antioxidant and radical scavenging activity (Suhaj, 2006; Moreno et al., 2006) of the substances isolated from these plants can be linked to their high potential in treatment and prevention of cancerous, cardiovascular and inflammatory diseases (Kingherbs, 2009; Morrison, 2009). A considerable amount of research work has been devoted to developing reliable methods for separation, identification and quantitative analysis of extracts of aromatic herbs and spices such as rosemary (Rosmarinus officiallis L.) (Cuvelier et 0263-8762/$ – see front matter © 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.cherd.2010.07.002