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Morozova K.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Schmidt O.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Schwack W.,University of Hohenheim
European Food Research and Technology | Year: 2014

White wine spoilage due to oxidation is a major concern during post-fermentation treatments and bottling. In this study, we explored the effects of different oxygen and free SO2 levels and ascorbic acid addition on the development of white wine. Riesling wine was bottled in 500-mL bottles under screw caps with four different headspace volumes (0, 10, 20 and 30 mL), two levels of free SO2 (45 and 70 mg/L) and with and without ascorbic acid (250 mg/L) addition giving 16 wines for analysis. Cold stored (at 5 °C) control was used as reference for data analysis and sensory evaluation. Dissolved oxygen and the oxygen in headspace were measured in the resulting 17 wines. Free and total SO2 concentrations, ascorbic acid concentration, colour, redox potential and antioxidative capacity were measured regularly in wine samples. After 6 months of storage, the wines were evaluated using descriptive sensory analysis. Both sensory and analytical results showed significant differences among the wines. Intensive wine exposure to oxygen (headspace volume) affected colour, free and total SO2 rate, and the overall sensory quality of wine. Ascorbic acid addition had positive effect on the sensory evaluation of wines and on SO2 levels, whereas combined with large headspace volumes, provoked intensive browning in wine samples. © 2014, Springer-Verlag Berlin Heidelberg. Source


Morozova K.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Schmidt O.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Schwack W.,University of Hohenheim
European Food Research and Technology | Year: 2014

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 oxygen, and iron and copper addition on changes in analytical 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 dissolved oxygen, free and total SO2 and colour were monitored 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 SO2 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. © 2013 Springer-Verlag Berlin Heidelberg. Source


Hempfling K.,TU Munich | Fastowski O.,TU Munich | Kopp M.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Pour Nikfardjam M.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Engel K.-H.,TU Munich
Journal of Agricultural and Food Chemistry | Year: 2013

Volatiles of gooseberries (Ribes uva cripsa L.) were isolated by means of vacuum-headspace-extraction, and the obtained concentrates were analyzed via capillary gas chromatography-mass spectrometry. To ensure the quantitation of highly volatile compounds, headspace analysis was additionally performed on selected batches. C6-components (e.g., (Z)-hex-3-enal, (E)-hex-2-enal), derived from lipid oxidation, and short-chain esters (e.g., ethyl acetate, methyl butanoate, ethyl butanoate) turned out to be the major compound classes in the fresh fruit. The compositional variability was demonstrated by analyzing several gooseberry varieties at different stages of ripeness. The contributions of volatiles to the gooseberry aroma were assessed by using gas chromatography-olfactometry in combination with aroma extract dilution analysis and calculation of odor activity values. C6- components and esters were shown to be responsible for the green and fruity character of fresh gooseberries. © 2013 American Chemical Society. Source


Morozova K.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg | Schmidt O.,Staatliche Lehr und Versuchsanstalt fur Wein und Obstbau Weinsberg
Mitteilungen Klosterneuburg | Year: 2012

The main aim of this study was to compare several instruments for carbon dioxide and oxygen measurement in wine. For carbon dioxide determination CarboQC, Orbisphere 3568 and Agitation Cylinder were used. Oxygen measurements were performed with PreSens, OxyQC and Orbisphere 3650. Sample bottles equally treated to have the same carbon dioxide or oxygen content were used for the measurements. Measurements were undertaken in the range from 0 to 2200 mg/l for carbon dioxide and in the range from 0 to 12 mg/l for oxygen. Developing correlation graphics and regression coeficients it was demonstrated that CarboQC and Orbisphere 3658 were effective for carbon dioxide measurement in the whole measurement range. Agitation Cylinder can also be used for this purpose at normal atmospheric pressure. Oxygen measurement with PreSens, OxyQC and Orbisphere 3650 showed good reliable results. Results obtained with all three instruments showed good correlation against each other and the initial pressure. So any of these devices can be used for oxygen determination in wine. However, more research should be made taking in consideration limitations of the proposed method for sample preparation. Counter pressure fillers should be used to obtain wine samples with gas concentration higher than saturation level. Source

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