micro-oxygenation in contemporary winemaking - Cape Wine ...

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Micro-oxygenation in Contemporary WinemakingA number of other possible disadvantages of micro-oxygenation are mentioned in theliterature but have not yet been confirmed. For example, there are unanswered questionsabout: The impact of micro-oxygenation on wine anti-oxidant capacity (and therefore thehealth benefits of red wine) (de Beer et al., 2008); The long-term ageing potential of treated wine; Whether or not micro-oxygenation increases the production of sulphide dimers; and The effects of micro-oxygenation on other important aroma compounds such aspyrazines (Dempsey, 2001).14
Micro-oxygenation in Contemporary WinemakingCHAPTER 5: MICRO-OXYGENATION METHODS AND TECHNIQUESLike many other vinicultural practices, there is unfortunately no consistent approach to theapplication of micro-oxygenation. What is common is the use of specialised equipment todeliver measured amounts of oxygen to wine. Different suppliers have developed slightlydifferent machinery but the basic principles of the different technologies remain similar.However, there is significant variation in the timing, dose and duration of oxygen treatmentrecommended by different suppliers and practitioners. Indeed, the industry seemscompletely opposed to the idea of a standardised recipe for micro-oxygenation and hasstrongly promoted the idea that treatment needs to be tailored to the needs of each wine(Rieger, 2000; Vinovation, 2001b). This approach is clearly appropriate but, of course, itdoes make things somewhat complicated for the novice micro-oxygenator.This Chapter provides a brief overview of the practical methods of micro-oxygenation. Theunderlying principles and common applications of micro-oxygenation are outlined first. Thatis then followed by a description of the basic equipment in current use before exploringsome of the practical issues in actually managing micro-oxygenation.5.1 BASIC PRINCIPLES OF MICRO-OXYGENATION TREATEMENTThe key challenge of micro-oxygenation treatment is to promote beneficial oxidationreactions whilst avoiding excessive oxidation which would spoil the wine.Therefore, one of the most important fundamental principles of micro-oxygenationtreatment is that the rate of oxygen addition to wine should be lower than the rate at whichthe oxygen is consumed through chemical reactions (Lemaire et al., 2002; Pour-Nikfardjamand Dykes, 2003; Jones et al., 2004).The ability of a wine to take up oxygen, its oxygen absorptive capacity, is mainlydetermined by its total phenolic content because it is the phenolic compounds in wine thatreact with oxygen. So a light white wine could take up about 60 ml O 2 /L whereas the figurefor red wine is more in the order of 600 ml/L (Singleton, 1987). However, it is somewhatmore complicated than that. For one thing, different categories of phenolic compoundsreact differently with oxygen so that it is the types of phenolics present, rather than the totalphenolic concentration, that is relevant. More importantly, the total absorptive capacity of a15
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