This article first appeared in the July/August, 2017 edition of The Wine and Viticulture Journal. Published by Winetitles Media, Adelaide.

What’s in the MOX?

By Mark O’Callaghan

From this issue of the Wine & Viticulture Journal, long-time contributor Cathy Howard will be joined by Wine Network Consulting’s Mark O’Callaghan and Quealy winemaker Dan Calvert who will rotate in continuing Cathy’s legacy of writing a practical winemaking column in every issue. Combined, the trio will present a variety of views and experience on aspects of the wine production process. Mark kicks off his inaugural contribution with a look at micro-oxygenation.

Remember all the fuss about micro-oxygenation (MOX] some years back? A new technique that enabled producers of (mostly] red wines to emulate barrel maturation by efficiently and accurately dissolving just the right amount of 02 into tanks. It addressed reductive and green characters in the treated wines, improved texture and was central to the appeal of some of the most successful big commercial blends Australia has ever produced.

Much has changed in the last 10-15 years, so I decided to speak to some winemakers in Australia to discuss how MOX is being used today, what is new, what has changed and why? Two such changes I was especially keen to discuss with respect to their effect on MOX requirements were the millennial drought (stressed canopies, green notes, dull fruit and occasional salinity effect] and the new generation of mechanical harvesters (brighter fruit characters, better texture and much less greenness].


While MOX may still feel relatively new, chances are many of your vintage crew were not even born when it was first approved by the European Commission in 1996, after its development in France in the early 1990s.

Small, measured injections of oxygen into (mostly] red wines improved texture through tannin polymerisation which had great success – especially with tougher varieties. It also led to increased fruit brightness by addressing reduction, improved colour and was effective in ameliorating green characters, making it especially popular in Chile.

The other major benefit, of course, was financial. By using MOX in conjunction with oak alternatives, winemakers were able to do an impressive job of replicating many of the maturation characters of barrel ageing without the cost or microbial risks of using older oak. In addition to the many wine show trophies won by wines using MOX, one of the best examples of its effectiveness in managing texture, brightness and having wines ‘ready to drink’ relatively quickly was Rosemount with its hugely successful large blends of the 1990s.


Thus far, one could be forgiven for thinking this piece might be an obituary for an outdated or redundant method. While reports of its death may be greatly exaggerated, the fact is MOX is nowhere near as popular as it once was in Australia and New Zealand, and my inquiries found there have been three main drivers behind this.

The first seems to be the shift in supply and demand balance from boom to bust and !hopefully] back to balance. One of the large company winemakers I spoke with – who preferred to remain anonymous so we’ll refer to him as Winemaker A – had a very interesting perspective on its use over the business cycle:

“During the boom we used it a lot. We had to get big blends out the door quickly and it was great to get them ready to go – very effective. Once we found ourselves in surplus, that was it. There was absolutely no interest. None .. .We couldn’t have wines ageing quickly in tank when what we needed was the exact opposite … ” The second major change from the 1990s noted by interviewees was the end of the millennial drought and the tough, chewy texture in so many red wines during that period. Continued Winemaker A:

“Yeah, I’d agree with that. We used it a lot on reds from the South East – Padthaway, Langhorne Creek, Wrattonbully; areas where we probably had more salt effect than we realised too. Those wines then had much better texture and were juicier after the drought…” In terms of textural changes since the early 2000s, these have also been influenced by shifts in market preference and winemaking style. I spoke with another large company winemaker – who also wished to remain anonymous so we’ll call him Winemaker B – who summed up this evolution:

“The market has changed a lot and the winemaking is more sensitive now too. We’ve gone from that ‘big is beautiful’ era of the 2000s to making reds that are tighter, finer, a little more reductive – just look at what has happened with Pinot Noir and cooler climate Shiraz. If that’s what you’re trying to do, then MOX is probably not the tool for it.”

These observations are entirely consistent with my own experience from the late 1990s and similar to the way some houses are using it today. Ross Pamment, senior winemaker for Houghton plus a friend and former colleague] noted:

“For texture, ifs now more of a remedial thing – for reduction or for reds that aren’t responding to finings the way we’d like. We’ve got a lot of MOX gear that’s about 15 years old but we don’t use it much now.”

The third and final observation which came up consistently was simply around bad experiences during the early years. Several winemakers relayed stories of the difficulty in monitoring many tanks undergoing MOX during the boom years and being somewhat ‘bruised’ by tanks appearing “more mature than they should have”.

With all of these things changing slowly over time, the shift was probably best summed up by one winemaker:

” … you know, I can’t really remember why we stopped. It just sort of dropped off the radar … ”


Unsurprisingly, the way MOX is being used today seems to reflect a change back to supply/demand balance, an improved understanding of how to use it judiciously, and advances in the equipment.

With respect to the improvements in sales and storage times, Pamment said, “that’s where we use it most – when we have to release something quickly and the pressure is on for bottle prep.” This experience is also reflected in Winemaker ft:s feedback:

“Once the age of release started getting shorter, we thought ‘let’s start playing with it again’. We’ve got more rigour and better sinters this time. With things like Cabernet from Padthaway and Langhorne Creek, or early-release reds going to China, it’s really good for softening.”

And on the matter of improved understanding of its use, Winemaker B explains:

“It certainly works to deal with greenness or soften things, making them more supple, but it can also prematurely age – especially the weaker wines. Back in 2011 when we were faced with some pretty thin and weedy wines, we backed right off to a little MOX pre-SO2 but nothing after that.”

With full and medium-bodied reds today, it is much more common to find producers using rates of approximately 10-20ml/L/month before M LF and then 2-5ml/L/month thereafter, with weekly tasting and recording of notes for each wine. With an approach along these lines [up or down depending on the wine] it is highly unusual to push a wine too far.


As with so many other things, suppliers have been pressured to improve their equipment and there are a number of new options available these days if one is in the market.

Thomas LeClerc, managing director of Viveleys Australasia, has been observing more customers applying MOX to varieties such as Chardonnay, plus other whites and rose as juices. In addition, the company’s new generation units have much better automation and control, making them easier to drive and having better precision with the inclusion of dissolved oxygen monitoring. These have been trialled on a commercial scale with Winemaker A, producing very promising results thus far.

Another development is delivery of oxygen at the molecular level through a membrane, rather than a ceramic sinter, using the Wine Grenade. Hamish Elmslie, chief executive of Wine Grenade, is unsurprisingly bullish about results so far and Wine Grenade’s potential. According to Elmslie, the effect is much closer to genuine barrel maturation, with better oak integration and texture, plus is easier to clean and simpler to use.

Tony Bish, chief winemaker at Sacred Hill, in New Zealand’s Hawke’s Bay, has been very pleased with Wine Grenade’s results on Pinot Noir so far. In addition to seeing wines with brighter fruit and more supple texture at lower oxygen rates (compared with traditional MOX]. there has been another very pleasing aspect for smaller wineries with smaller tanks. According to Bish, as oxygen is delivered at the molecular level, the solubility is much better, overcoming the need for the same head pressure (tank height] as one finds in the tank farms of the big houses. For readers who are reconsidering MOX in their cellars, these two options may indeed be worth adding to the shortlist. Finally, one new technology pushing in the opposite direction is the next generation of mechanical harvesters, which are delivering much brighter fruited wines with greatly diminished green characters into cellars all over the world. Many of these wines show almost no need for MOX whatsoever and Ross Pamment, in particular, is adamant: “Yep. Absolutely agree. They’re fantastic.”


Notwithstanding the promising green shoots of recovery in the wine world, most of us are still incredibly busy with very little spare time or capital to explore (or rediscover] techniques that are new, or at least new to us. Furthermore, there is always a degree of risk and so trials are often applied to problematic parcels, meaning the final wine is usually underwhelming, regardless of the merits of the technique.

The fact remains, however, that thoughtful and judicious use of MOX is potentially a very useful tool in the arsenal of anyone making wine (especially red] at prices that cannot support barrel maturation. We all know that snobbishness simply cannot be found in the world of winemaking, so any obstacles to the consideration of MOX are purely operational. Fortunately, we are now in an environment where there are many underutilised units in place and some very affordable modern options available for lease or sale, if starting from scratch. Winemaker B seems to have a good perspective on the matter: “I’m definitely a fan but it really depends on the parcel. As with everything, you need to know what you are doing and pay attention. Too much and the wines can appear like blobs – the old ‘tadpole” analogy.”

One final, and endlessly amusing, aspect about the use of techniques such as MOX is that in the common imagination, they are tightly associated with the stereotype of the New World “industrial’ winemaker, devoid of empathy, romance or imagination. The joke, of course, is that so many of them were developed in France in the first place.

Mark O’Callaghan is senior consultant and director at Wine Network Consulting. Mark joined WNC in 2013 after working independently for two years. Prior to this, he spent 14 years with Accolade Wines (formerly BRL Hardy}, including eight years as senior winemaker and winery manager for Yarra Burn in Victoria’s Yarra Valley. He has also made wine in McLaren Vale, Heathcote, Great Western, the Pyrenees, Austria and Sicily.


Ronbinson, J. and Harding, J. [Eds) 12015) The Oxford Companion to Wine, 4th edition. Oxford University Press.

Mark O’Callaghan is Managing Director of Wine Network Consulting. Based in the Yarra Valley, but working on projects around Australia, the UK and China, Mark is a regular contributor to various wine industry bodies and wine show judge. The views expressed here are his own.