title: Understanding the Effects of Roasting on Antioxidant Components of Coffee Brews by Coupling On-line ABTS Assay to High Performance Size Exclusion Chromatography.
abstract: BACKGROUND
  Coffee is a widely consumed beverage containing antioxidant active compounds. During roasting the phytochemical composition of the coffee bean changes dramatically and highly polymeric substances are produced. Besides chlorogenic acids that are already present in green coffee beans, melanoidins show antioxidant capacity as well.
  
  
  OBJECTIVE
  To employ post-column derivatisation by coupling high performance size exclusion chromatography (HPSEC) to an antioxidant assay to investigate the effect of roasting on the properties of antioxidant active compounds in coffee brews.
  
  
  METHODS
  We have investigated the antioxidant capacity of Coffea arabica (Arabica) and C. canephora (Robusta) beans that were roasted over the full spectrum of roast conditions (four roasting speeds to three roast degrees) by comparing the results from HPSEC coupled on-line to the ABTS assay with those from two batch assays, Folin Ciocalteu (FC) and oxygen radical absorbance capacity (ORAC) assay.
  
  
  RESULTS
  The antioxidant capacity showed a general decrease towards slower and darker roasted coffee for all three assays, indicative of heat degradation of active compounds. Hence, low molecular weight (LMW) compounds such as chlorogenic acids (CGAs) decreased progressively already from relatively mild roasting conditions. In contrast, high molecular weight (HMW) compounds (e.g. melanoidins) increased from light to dark roast degrees with lowering magnitude towards slower roasting profiles.
  
  
  CONCLUSIONS
  By coupling HPSEC on-line to the ABTS assay we were able to separately quantify the contribution of HMW and LMW compounds to the total antioxidant capacity, increasing our understanding of the roast process. © 2016 The Authors. Phytochemical Analysis Published by John Wiley & Sons Ltd.
authors.affiliation: Zurich University of Applied Sciences, Institute of Chemistry and Biotechnology, Einsiedlerstrasse 31, CH-8820, Wädenswil, Switzerland.
authors.forename: Sebastian E W
authors.initials: SE
authors.lastname: Opitz
authors.affiliation: College of Physical Sciences and Technology, Guangxi University, Nanning, 530004, Guangxi, China.
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Goodman
authors.affiliation: Bühler AG, Gupfenstrasse 5, 9240, Uzwil, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Keller
authors.affiliation: Zurich University of Applied Sciences, Institute of Chemistry and Biotechnology, Einsiedlerstrasse 31, CH-8820, Wädenswil, Switzerland.
authors.forename: Samo
authors.initials: S
authors.lastname: Smrke
authors.affiliation: Zurich University of Applied Sciences, Institute of Chemistry and Biotechnology, Einsiedlerstrasse 31, CH-8820, Wädenswil, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Wellinger
authors.affiliation: Bühler AG, Gupfenstrasse 5, 9240, Uzwil, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schenker
authors.affiliation: Zurich University of Applied Sciences, Institute of Chemistry and Biotechnology, Einsiedlerstrasse 31, CH-8820, Wädenswil, Switzerland.
authors.forename: Chahan
authors.initials: C
authors.lastname: Yeretzian
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002850:Chromatography, Gel / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003069:Coffee / Q000737:chemistry*; D013058:Mass Spectrometry
chemical_list: D000975:Antioxidants; D003069:Coffee
keywords: ABTS•+; Folin-Ciocalteu; HPSEC; ORAC; antioxidants; coffee; post-column derivatisation