The aging of red wines is essentially an oxidative process. This has always been the case. The evolution (positive or negative) of the features of colour, flavour and astringency takes place within the cogs of one single engine: oxygen. This is irrespective of which aeration or oxygenation technique you choose, from the racking stage, to the wooden barrel up until macro and micro-oxygenation. For each wine and for each refined style, however, the oxygen has to be managed, it should neither include too much nor too little in order to avoid complications of various types.
Micro-oxygenation is a method for managing wines more accurately, in the right manner, and with the desired dose. The rest is just a question of style and choice, a tool held by the grower and the winemaker.
Criticism sometimes levied against this technique is completely unfounded: is a breadknife a harmful tool? Obviously it isn’t, however when used in its own way it is useful and requires both brains and skill (it should not be given to a child or to a serial killer).
Finally, the research world has some exciting news which will clarify some points on the how oxygen should be managed properly in the refinement of red wines.
How much oxygen for my wine?
Using the results of their studies, Boulton and Singleton, of Davis University, California, two pioneers in the study of phenolic compounds and their reactions to wine, have developed a link about the possible relationship between the quality of a wine, expressed in terms of scoring points, and the range of oxygen consumption. Whereas, of course, the ratio of oxygen/quality is dependent on the type of wine (or rather the amount of reactive polyphenols) and the range recorded takes into account all of the contributions of oxygen which the wine encounters in its lifetime (during handling, batching, oaking in wood, etc.), it has been observed that types of wines such as Sherry see their quality increase with the level of oxygen consumed, while the opposite occurs with white wines. In red, contrary to this, there is an area in which the quality grows along with the level of oxygen, this remains stationary, and then decreases. “In medium stat virtus”, while at the extremes there are faults of reduction or oxidation, but also the absence of evolution (have you heard of wines becoming “stuck” in its evolution?) or its excess.
Micro-oxygenation and respect for the style and varietal features
In red wines, the concentration of the various compounds of the phenolic profile defines the structure of a wine, whilst also giving an indication as to its oxygen requirements, and consequently the order of the level of the dosages to be taken when using the technique of micro-oxygenation.
A more structured wine will require more oxygen than another one less concentrated and more “fragile”. For this last wine lower dosages are required together with a greater focus on oxidative risk management and on any changes in its organoleptic parameters. This is true throughout every phase of its manufacturing process, not only during micro-oxygenation.
At the time when the dose is selected, it is necessary to define the purpose, and the style, for which you apply the micro-oxygenation and this is the impact desiderd for each the wine. The same thing doesn’t even happen when selecting how the oaking process works (how much and will new wood be required?) or when a clarification is sought?
A criticism sometimes advanced to micro-oxygenation is that it influences the flavour profile of the wines, standardises them and reduces the amount of variation and tipicity and is suitalbe for the sole purpose of “simply” experiencing a taste of global wines. The answer is that in fact micro-oxygenation is a tool with which you can work alongside various impacts and doses ranging from the lowest and those which most typically respect the wine, to the highest which cause the wine in question to undergo significant evolution. The remainder is largely a matter of style.
The technique of micro-oxygenation of red wines can be used in a different and in more or less invasive manner on the varietal features of the wines.
It can be used at discrete levels (for what we call low-impact) with the aim of providing the necessary amount of oxygen to the wine so that it can evolve and be maintained in a redox equilibrium which enhances the varietal characteristics of the grape even during periods of long-term aging. This is the approach adopted by Parsec from the earliest times, initially mainly for caution, and the one which over time the experience and new-found knowledge on the evolution of red wines has confirmed to be the most accurate.
The other style, which we call “high impact” on the organoleptic profile of wine is the one in which you are seeking the softening tannins and one which strives for the development of olfactory features of evolution such as plum or chocolate, even during periods of rapid aging. Of course, a legitimate choice, suitable for example in wines which need to be prepared in a short space of time, and which do not have a long shelf life when inside a bottle. It is a choice, however, which is not suitable for wines which will be subject to long-term refinements inside the bottle, and which cannot improve the varietal characteristics of the wine, as it favours an aromatic sweet, ripe, or overripe component.
The impact being sought should be clear from the outset because it influences not only the final results, but also, quite possibly, the life expectancy of the product.
A new marker for premature aging red wines
Recently, some French researchers (Dubourdieu et al., 2012) have identified an olfactory and aromatic marker which is linked to the premature aging of red wines, the so-called Premox, one which is associated with the characters described as prune, stewed fruit and dried figs. The responsible for these characters would be the γ-nonalacton and 3-methyl-2, 4 – nonane dione (MDN) and their formation would occur in oxidative conditions.
The production of the first one in particular seems to be favoured by some winemaking conditions such as the high degree of ripeness of the grapes, the low concentration of sulphur dioxide, the high pH value, and the use of wood, with higher levels (albeit lower than the perception threshold) being recognised in new barrels rather than in those during the first or second year of use.
Also related to these new findings, we can say that the approach towards micro-oxygenation is more closely linked to what we called “low impact” where in fact, in compliance with the varietal characteristics of the wine, the characters of oxidative evolution are neither called for nor achieved.
The aromatic markers of premature aging offer a new aspect when it comes to understanding the complex relationship between oxygen and wine, enhancing process control, and finally looking even further afield, at the period of aging inside a bottle, which unfortunately is often neglected.
As all the techniques the use of micro-oxygenation has seen various ages. Even the barrel, for example, has been used in previous decades in an indiscriminate way meaning that today it is used more rationally and maturely, which is a preference for the effects of technology and which does not rule out the actions of aromatic oak and roasting.
The same was also for micro-oxygenation: there was an initial moment of youthness, in which some winemakers went in search of a marked effect and a direct impact on the character of the wines. Is to that style to which are directed those criticism that in some cases have been made to the use of this technique. But now even micro-oxygenation has reached its maturity, it is a more widely known phenomenon, you have more control of oxidation and oxygen management also in other manufacturing processes, and what you want is not an enhancing technique, but a tool to help the wines to bring out their characters, and features from both their variety and their local region. Even in its infancy, however, some were less inconsiderate or reckless of others: not to be those who claime “we told you so,” but Parsec has always sustained a low impact of oxygen on wine…by