Vol.:(0123456789) 1 3 European Food Research and Technology (2018) 244:1953–1961 https://doi.org/10.1007/s00217-018-3107-3 ORIGINAL PAPER Electrochemical, photometric, and chromatographic methods for the evaluation of organic matter and bioactive compounds in cofee brews Constantina Grigoriou 1,2  · Sotirios Karavoltsos 2  · Andriana C. Kaliora 1  · Aikaterini Sakellari 2  · Marta Plavšić 3  · Manos Dassenakis 2  · Nick Kalogeropoulos 1 Received: 27 March 2018 / Revised: 6 June 2018 / Accepted: 9 June 2018 / Published online: 18 June 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Sensitive electrochemical techniques were combined with photometric and chromatographic assays to characterize the organic matter, determine selected bioactive compounds, and evaluate antioxidant properties of popular cofee brews. Phys- icochemical properties of organic material released in Greek/Turkish, espresso, flter, and instant cofee brews were inves- tigated measuring copper-complexing ligands (L T ), surface active substances (SAS), and catalytically active compounds (CAC). In addition, organic carbon, total and individual phenolics, and cafeine were measured. The content of Maillard reaction products was estimated. Antioxidant potential was primarily assessed measuring DPPH-radical scavenging capac- ity and ferric-reducing antioxidant power. The potential inhibition of human serum lipoprotein oxidation in vitro was also investigated. The efect of fast or slow sipping of Greek/Turkish cofee was investigated as regards organic matter release and antioxidant activity. Cofee brews release Cu complexing ligands at diferent concentrations (74.6 and 364 mM in flter and Greek/Turkish cofees, respectively). Cofee brews contained 50.1–445 mg cafeoylquinic acids (CQAs) per 100 mL, the 47–53% being chlorogenic acid. Among cofee brews, espresso contained more CAC, SAS, copper-complexing ligands, cafeine, browned compounds, and phenolics. In addition, espresso exhibited higher antiradical activity and reducing power, while Greek/Turkish cofees higher resistance to serum lipid oxidation. Keywords Cofee brews · Organic matter · Copper complexation · Phenolic compounds · Cafeine · Antioxidant activity Introduction Cofee is commonly consumed worldwide [1]. Cofee con- sumption is related to many health benefts [2, 3] owed to its antioxidant activity [4]. Apart from cafeine, roasted cofee contains also phenolic compounds, niacin and its precursor trigonelline, soluble fber, nicotinic acid, and melanoidins; the latter, produced according to the intensity of roasting [5], are responsible for cofee’s color and partly for its antioxi- dant and metal-chelating properties [2, 6–8]. The antioxidant potential of cofee is mostly linked to phenolics [9, 10]. The antioxidant activity of cofee is attributed to organic compounds that scavenge free radicals and chelate redox active metals, which are considered signifcant exogenous sources of Reactive Oxygen and Nitrogen Species (ROS, RNS) [11]. The antioxidant activity of cofee brews involves chromo- gen compounds of a radical nature which stimulate reductive oxygen species [12]. Herein, radical scavenging, reducing Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00217-018-3107-3) contains supplementary material, which is available to authorized users. * Nick Kalogeropoulos nickal@hua.gr 1 Laboratory of Chemistry-Biochemistry-Physical Chemistry of Foods, Department of Nutrition and Dietetics, Harokopio University, 176 71 Athens, Greece 2 Laboratory of Environmental Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 157 84 Athens, Greece 3 Center for Marine and Environmental Research, Ruder Bošković Institute, P.O. Box 180, 10002 Zagreb, Croatia