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Alcohol Case Study

Decent Essays

Alcohol is an integral aspect of Australian culture, accounting for $14.1 billion of expenditure every year (Australian Securities & Investments Commission, 2017). By far the most popular type of alcohol in Australia is bottled wine, which makes up 34% of alcohol consumed by Australians, and of this approximately 50% is white wine (Australian Bureau of Statistics, 2015). With white wine making up such a major part of everyday life for so many Australians, it is important for manufacturers to ensure the quality of the wine they produce. One way this is achieved is through addition of sulphur dioxide or SO2 (refer to figure 1).
SO2 exists in wine in two forms: free and bound. Free SO2 exists in the wine unbound to other compounds and is …show more content…

Oxidation in wine is caused by the reaction of dissolved oxygen in the wine with compounds within the wine, including polyphenol oxidase (PPO) and ethanol (Smith, Monteath, Gould, & Smith, 2010). This is a type of redox reaction, which is a reaction characterised by a transfer of electrons (LibreTexts, 2014). Redox reactions consist of an oxidation half-reaction, in which electrons are gained, and a reduction half-reaction, in which electrons are lost, taking place simultaneously in an overall redox reaction. To directly prevent these reactions, SO3- in the wine reacts directly with the oxygen in the wine according to the equation:
SO3-(aq) + O2(aq) + H2O(l)  H2SO4(aq)
However as SO3- exists in the wine only in very small concentrations, a majority of the antioxidant actions occurs from molecular SO2 reacting with the wine compounds themselves. Firstly, molecular SO2 reverses the oxidation of colourless diphenol to brown o-quinones by binding to and inhibiting PPO, which catalyses the oxidation (refer to figure 3) (Martin, 2011). Molecular SO2 also prevents the oxidation of ethanol by hydrogen peroxide (produced by the oxidation of hydroxyl-phenols) into acetaldehyde (Rotter, 2002) which occurs in the

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