Investigating the effect of micro-oxygenation and glutathione on reductive odours in red wine

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dc.contributor.advisor Kilmartin, P en McDonald, Sarah en 2013-02-10T21:33:43Z en 2013 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Trinity Hill is a premier winery based in the Hawkes Bay. They have been making Syrah for thirteen years and every year they have had problems with their Syrah undergoing unexpected reductive cycles. Glutathione is a reductive species naturally present in grape juice with strong antioxidant properties; the effects of the presence of sulfur dioxide and glutathione during MOX. This project aimed to evaluate the effect of glutathione and MOX on the reductive sulfur compounds in red wine. The project was carried out in three Parts: 1. Comparison of SO2 and glutathione in wine undergoing constant MOX. 2. Comparison of constant delivery of oxygen with regular pulses of oxygen. The pulses aimed to mimic the process of racking the wine. a. A sub-investigation which evaluated a commercial product called BioArom® was also carried out. 3. Monitoring the oxygen uptake within a new barrel by the oak. The tannin content of the samples was measured using the AWRI methyl cellulose precipitable tannin assay. The wine colour and phenolics were measured using Iland et al’s method (2000). An enzymatic assay was used to measure the acetaldehyde content. The polyphenol content of the wine was measured using Reverse Phase High Performance Liquid Chromatography (RP-HPLC). The reductive sulfur compounds were measured using the method developed by Dang-Dung (2011) – headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography – mass spectroscopy. The data was analysed in SPSS 17.0. A one-way ANOVA analysis and the Turkey’s Honestly Significant Difference (Turkey HSD) Post Hoc test were carried out. Part one: the glutathione and SO2 were both consumed rapidly once added to the experimental wine. There was minimal difference in the concentrations of polyphenols and reductive sulfur compounds between the different treatments. Part two: the MOX treatment had significantly lower concentrations of tannin and acetaldehyde. There was essentially no difference between the treatments in polyphenol concentration. The PULSE treatment had significantly lower concentrations of quercetin. With the exception of carbon disulfide, there was no significant difference between the treatments in the concentration of reductive sulfur compound. The PULSE treatment had significantly lower concentrations of carbon disulfide and the MOX treatment had lower concentrations than the control. The addition of BioArom appeared to stimulate the production of glutathione by the yeast. The wine which was treated with the BioArom had lower concentrations of carbon disulfide, diethyl sulphide and 3- (methylthio)-1-propanol. Part three: the experimental results so not show any clear trend; it is doubtful if the results are truly representative of what is occurring within the barrel. No conclusions can be drawn from this data. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
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dc.rights.uri en
dc.title Investigating the effect of micro-oxygenation and glutathione on reductive odours in red wine en
dc.type Thesis en The University of Auckland en Masters en
dc.rights.holder Copyright: The Author en en
pubs.elements-id 373018 en
pubs.record-created-at-source-date 2013-02-11 en

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