1 3 Eur Food Res Technol DOI 10.1007/s00217-013-2142-3 ORIGINAL PAPER Impact of headspace oxygen and copper and iron addition on oxygen consumption rate, sulphur dioxide loss, colour and sensory properties of Riesling wine Ksenia Morozova · Oliver Schmidt · Wolfgang Schwack Received: 19 August 2013 / Revised: 27 October 2013 / Accepted: 11 December 2013 © Springer-Verlag Berlin Heidelberg 2013 Introduction Oxidation is a common spoilage in white wines. Contact with air, oxygen ingress at bottling may influence develop- ment of the bottled wine [1, 2]. Modern measurement tech- niques allow the amount of dissolved oxygen in wine to be quantified, along with the gaseous oxygen in the headspace of the bottle [3]. Iron and copper are of major interest in wine due to their ability to form hazes or casses, such as ferric tannate casse, ferric phosphate casse and copper casse, which cause instability and cloudiness in wine [4]. Iron and copper are essential nutrients for plants, but can be toxic to people in exceeding concentrations [5]. These metals are always pre- sent in wine as trace amounts, coming from grapes, soil [6– 8] viticulture practices [9] or pesticides [10, 11]. Secondary sources of iron and copper may be oenological equipment [12] in the cellar or fining agents [13, 14]. Iron and copper are minor metals found in wine in the range 0.1–10 mg/L [15]. Iron and copper may contribute to the sensorial quali- ties of wine. High concentrations of both total iron and ferrous ion were reported to enhance the intensity of fishy aftertaste of wines paired with seafood [16]. Copper may also change the sensory profile of wine in concentrations exceeding 0.5 mg/L [17]. Schmidt [18] reported a pro- nounced bitter taste in wines with copper concentrations higher than 1 mg/L. Recent studies in model wine solutions showed the key role of iron and copper in oxidation reactions occurring in wine as oxygen activators [19–21]. The development of reactive oxygen species resulting from hydroperoxyl radical formation was regarded as stronger oxidants as the molecular oxygen [22]. However, the latest study of Danilewicz [23] showed that catechol is not reacting with Abstract Oxygen ingress at bottling is crucial for the wine development during storage. Iron and copper are known to catalyse the oxidation processes in wines. The aim of the present study was to evaluate the impact of oxy- gen, and iron and copper addition on changes in analyti- cal and sensory parameters during storage. A Riesling wine was bottled with various oxygen concentrations determined by the headspace volume in the bottle (0, 10 and 20 mL) full with ambient air. Iron (1 mg/L) and copper (0.5 mg/L) were added to 50 % of the bottles. Headspace and dis- solved oxygen, free and total SO 2 and colour were moni- tored during 3 months post-bottling. Descriptive sensory evaluation took place in the end of the observation period. Fe and Cu addition had significant influence on the oxygen consumption rate, on the loss of SO 2 during storage, and on the sensory changes in wine. Initial headspace volume additionally made significant impact on the evolution of the sulphur dioxide and on the sensory profile of bottled wines. Keywords Wine · Metals · Oxygen · Wine oxidation · Sulphur dioxide · Sensory analysis K. Morozova (*) · O. Schmidt Staatliche Lehr- und Versuchsanstalt für Wein- und Obstbau Weinsberg, Traubenplatz 5, 74189 Weinsberg, Germany e-mail: kseniya.morozova@gmail.com O. Schmidt e-mail: oliver.schmidt@lvwo.bwl.de W. Schwack Institut für Lebensmittelchemie, Universität Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany