New insights into the role of selective and volumetric heating during microwave extraction: investigation of the extraction of polyphenolic compounds from sea buckthorn leaves using microwave-assisted extraction and conventional solvent extraction

Galan, Ana-Maria; Calinescu, Ioan; Trifan, Adrian; Winkworth-Smith, Charles; Calvo-Carrascal, Miguel; Dodds, Chris; Binner, Eleanor

Abstract

We report a direct comparison of microwave heating and conventional heating in solvent extraction by using exactly the same reaction conditions (including heating rate) in the extraction of polyphenols from dried sea buckthorn leaves. We have for the first time decoupled the effects of bulk heating rate and mixing regime from the fundamental microwave heating mechanism. We show that although microwave selective heating can increase the yield and quality of the polyphenols extracted, if the same bulk heating rate is applied there is no difference in treatment time and therefore theoretical energy requirements of the process. The first implication of these results for process intensification is that if microwave selective heating can be enhanced in scaled up processes through electromagnetic design, the extract yield and quality may be increased further. The second implication is that conventional extraction processes could be designed to provide the same heating rate and hence treatment time as microwave extraction, but any potential energy and space savings would have to be balanced against the increase in capital cost and complexity of the equipment. That said, the very small penetration depth of microwaves into ethanol/water solvent also poses design challenges in the scale up of microwave equipment.

Citation

Galan, A., Calinescu, I., Trifan, A., Winkworth-Smith, C., Calvo-Carrascal, M., Dodds, C., & Binner, E. (2017). New insights into the role of selective and volumetric heating during microwave extraction: investigation of the extraction of polyphenolic compounds from sea buckthorn leaves using microwave-assisted extraction and conventional solvent extraction. Chemical Engineering and Processing: Process Intensification, 116, 29-39. https://doi.org/10.1016/j.cep.2017.03.006

• Journal Article Type: Article
• Acceptance Date: Mar 11, 2017
• Online Publication Date: Mar 16, 2017
• Publication Date: 2017-06
• Deposit Date: Apr 12, 2017
• Publicly Available Date: Apr 12, 2017
• Journal: Chemical Engineering and Processing: Process Intensification
• Electronic ISSN: 0255-2701
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 116
• Pages: 29-39
• DOI: https://doi.org/10.1016/j.cep.2017.03.006
• Keywords: Microwave-assisted extraction (MAE); Sea buckthorn leaves; Polyphenolic compounds; Antioxidant activity; Selective heating; Dielectric properties
• Public URL: https://nottingham-repository.worktribe.com/output/851093
• Publisher URL: https://doi.org/10.1016/j.cep.2017.03.006
• Additional Information: This article is maintained by: Elsevier; Article Title: New insights into the role of selective and volumetric heating during microwave extraction: Investigation of the extraction of polyphenolic compounds from sea buckthorn leaves using microwave-assisted extraction and conventional solvent extraction; Journal Title: Chemical Engineering and Processing: Process Intensification; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.cep.2017.03.006; Content Type: article; Copyright: © 2017 Elsevier B.V. All rights reserved.