Innovative maceration for more options in the quest for perfect Pinot Noir

Many winemakers and viticulturists recognise Pinot Noir as one of the most intriguing of wine grapes to work with and quite a few of Australia’s wine science community share that view.

Dr Anna Carew, for example, calls it ‘a refined but challenging variety’ and even suggests, after describing some of its chemical idiosyncrasies, that it ‘might sound like a fool’s errand to get your head around Pinot Noir chemistry’.

Understanding Pinot Noir phenolics is a large focus for the viticulture and oenology group in the Tasmanian Institute of Agriculture (TIA). Dr Carew and colleagues have been funded by Wine Australia to continue their work on microwave and other innovative forms of Pinot Noir maceration, and look more broadly at ways to improve red wine process efficiency and product quality through enhanced phenolic extraction.

Processes to manage phenolic extraction have particular importance when making Pinot Noir table wine. ‘This is partly because the variety has a really unusual tannin distribution’, Dr Carew said. ‘In most red grape varieties there’s a large amount of tannin in skin and a smaller amount in the seeds, but with Pinot it’s the other way around.

‘This is partly because the variety has a really unusual tannin distribution’, Dr Carew said. ‘In most red grape varieties there’s a large amount of tannin in skin and a smaller amount is in the seeds, but with Pinot it’s the other way around.

‘Tannins are really important not just for the mouth feel of the wine, but because the tannin binds with the colour compounds to provide more stable colour. Pinot Noir can be fairly light in colour and can collapse with ageing if it doesn’t have sufficient colour, or sufficient tannin to bind the colour, or if the binding process is not effective.’

With Pinot Noir, the types of colour compounds available are relatively unstable, compared with other red varieties. Also, emerging research suggests that some sources of tannin may be less effective for making stable colour; the skin-tannin versus seed-tannin debate is still a live one for Pinot Noir.

For the team at TIA, the answer is to explore and refine a number of options for maceration that enhance control of phenolic extraction. The aim is to give winemakers a suite of possible approaches to suit the year, the fruit or their stylistic intentions.

In a recent trial, the researchers compared six alternative treatments against a control group based on the standard practice of an eight-day fermentation on skins. Two of the alternatives – cold soaking and extended maceration – are quite widely used in the sector. Two treatments are variations of the Controlled Phenolic Release (CPR) approach, which couples microwave maceration with managed hold time. The final two are what Dr Carew calls ‘this year’s wacky ones’ – in-line carbon dioxide (dropping the temperature to 10°C using dry ice) and ultrasound.

The initial aim for innovative maceration processes is simply to determine if there are distinct differences in the wine styles produced. The work is ongoing, but Dr Carew presented preliminary findings and some early observations at this year’s Crush 2015 conference in Adelaide.

Some of the results confirmed what the TIA team already knew – that using CPR treatment produces wines that are intensely coloured with high tannin concentration, for example, and that extended maceration appears to transition anthocyanin towards stable colour more rapidly than a standard eight days of fermentation on skins.

More significant was the emergence of some distinct differences associated with the more radical treatments. ‘What was exciting was that the carbon dioxide wines and possibly the ultrasound ones were starting to look different from the controls’, Dr Carew said.

Alongside the excitement is the reality that they must develop options that are as economically feasible as they are scientifically valid. They not only can’t cost too much, they also can’t lock up precious tank or cool store space during vintage, especially as vintage compression bites.

The right answers should have plenty of advocates, however.

‘In the days before and after Crush 2015 I was in Victoria for tastings with winemakers who have participated in our work and it’s very clear that they have ideas about the various styles of Pinot Noir they would like to make and they want options to more carefully manage phenolic outcomes if the fruit demands it,’ Dr Carew said.

‘In good years, a good winemaker stands back and just lets the fruit talk. But there are times when vintage pressures mean the winemakers have to be really on their game. The comment that winemakers were making during our tastings were that they could really have used some of these processes in 2011 when the volume and style of fruit made for a very busy vintage.

‘Winemakers just want options; they want a toolbox. It is not enough for our maceration processes to be scientifically proven. The sector needs practical tools that are reliable, economical and, most of all, can deliver the best kind of wine possible from the fruit to hand.’

Photo credit: Chris Crerar.