I suspect that people interested in fine wines are also interested in food and coffee.
Coffee has many parallels to wine, from growing to preparation and tasting. One of the channels on YouTube I like to watch is that of James Hoffman. He is an unashamed coffee geek who delves into every imaginable facet of coffee. Two of his videos, in particular, brought home to me this connection to winemaking, and more specifically, a technique we use in making Pinot noir, namely Délestage.
The two semi-clickbait titles were "Immersion coffee brewing is better than percolation" and "The ultimate French press technique"
The French press technique is immersion brewing. All the grinds sit in the water and are only separated at the last minute by the plunger, whereas filter and pour-overs are percolations, where the hot water flows through a bed of grounds extracting coffee on the way down.
One of the criteria in evaluating the two methods is to measure coffee extraction using a refractometer just as one would measure sugar in the vineyard. An important factor in coffee preparation is the coarseness of the grind particles. You can lose many hours watching Mr Hoffman expound on the virtues of impact vs burr grinders, flat vs conical and ceramic vs metal burrs. The holy grail is to achieve a uniform particle size with little variation around a chosen point. The degree of fineness desired is a function of the roast and grinding technique. He does recommend a coarser grind for French press and even more so for darker roasts.
In comparing immersion vs percolation at decreasing particle size levels, he found that the extraction increased with decreasing particle size for the immersion technique. The percolation extraction increased until the finest size, after which the extraction fell to its lowest value.
This seemingly paradoxical result is explained by channelling. The water flows through pores that form in the fine bed of grinds and do not pick up more coffee on the way through.
The immersion technique gives time for all the particles to come into contact with the water and plunger; it also forces a flow through the whole bed of coffee. It is impossible for channels to form.
You might be wondering what this has to do with Pinot noir, and I am about to tell you, but I would like you to keep in your mind the images of the French press and its plunger slowly pressing down, separating the fluid from the solids.
Many factors are influencing red wine quality before the grapes even reach the cellar. Still, every winemaker must make choices on crushing, destemming, whole bunch fermentation, stem inclusion, cold soak, cap management techniques, speed of fermentation, post-ferment maceration, when to press and how hard to press.
A winemaker is trying to achieve at this pivotal stage between juice and wine is a balanced extraction of the grape components to make the wine he has in mind. There must be enough colour extraction from the skins, but they will extract too many bitter and astringent tannins if they work them too hard. Too much mechanical agitation of the grapes will lead to many small vegetal particles that will increase the sediment forming at the bottom of the tank. These lees can trap colour leading to reductive conditions, the generation of sulphurous compounds and green vegetal tastes.
Opportunities for mechanical action on the grapes can occur during destemming and crushing, which explains why so many choose destemming, but not berry crushing or even going in whole bunch.
Pumping the grapes into the tanks can also put considerable stress on the grapes. Many careful producers will destem into a gondola or other moveable vessel and lift the intact grapes in batches into the fermentation tank.
Cap formation in a fast unchecked fermentation can lead to tremendous forces on the grapes, as any young winemaker tasked to hand plunge a fermentation will attest to. The cap can be so compact that one can easily stand on it without any danger of falling through. The forces of gravity working against the lifting forces of the CO2 create a very dense layer of skins above the fermenting juice. So compact, in fact, that no juice flows around the skins extracting colour and tannins. It also blocks the juice from oxygen and traps heat. Any juice in the cap is already saturated with extracted components and therefore cannot draw out any more colour or tannin from the skins. These are the reasons for mixing the skins with the juice. In trying to push through this cap, one puts even more stress on the skins and pips. In the meantime, yeast and small particles are starting to form on the bottom of the tank.
In all red winemaking, it is the renewing of contact between the juice or wine with the skins that determines the quantitative aspect of the extraction.
Surely pumping the juice from under the cap and over the skins would be the answer?
It is an option but not the best one. This is what is most often seen in red winemaking, wine being pumped through a sieve into an open-top tank to "aerate" and then sprayed on top of the cap. There are as many contraptions to do this as there are styles of coffee burr grinders.
The rule of thumb is to pump as long as it would take to displace three times the tank's volume. All the while, the wine with its yeast, skin particles and pips is being agitated through the pump. The colloidal matrix and co-pigmentation one is trying to build are constantly being disturbed.
The oxygen pick-up is minimal as the agitated wine releases all its dissolved CO2, which, heavier than air, blankets the surface and stops oxygen from contacting the wine. The same goes for the wine sprayed over a cap. It falls through the cap of CO2. This is not a good way to break up the cap and get the juice flowing around the skins extracting colour and tannins in the correct proportions. Here one can see how traditional pumping over parallels percolation coffee brewing.
A more thoughtful way to treat delicate Pinot noir was developed by the ICV and its champion at the time, now a consultant, Dominique Delteil. It is called Délestage, and its translation in this context is un-ballasting. It was also explained to me as a submarine venting air in its ballast tanks to submerge; this process was termed délestage.
The ICV describes it as "a method to optimize exchanges between the liquid and solid phases during maceration and is far superior to traditional methods of pumping over."
At the onset, it must be stated that this method is logistically demanding with regard to time and equipment. For starters, it ties up two tanks. Luckily Pinot noir is an early cultivar, and its early arrival in the cellar means there are still many empty tanks available.
So how does it work? It should start as soon as a cap has started to form. The wine is drained, preferably free-flow, through a sieve, into a large shallow tank to allow the CO2 to dissipate. It is advisable to introduce oxygen via a venturi. Oxygen can also be directly introduced into the destination juice tank.
This wine is then pumped into an empty tank. All the juice or wine must be drained from the grapes, and one can leave the valve open for the last drops to come out. At this early stage, the cap is not very solid, and the grapes are floating relatively weightless in the juice of their less fortunate companions. The majority of juice below the cap has not been in contact with the skins. Some yeast, but, at this stage, lots of skin fragments, small pieces of stems, pips and dust or soil from the vineyard have settled at the bottom of the tank,
A juice layer is just under the cap saturated with skin components comprised of pigments, tannins, and polysaccharides.
All of this is drained out to the new tank. Once the free juice/ wine is out, the cap has lost its supporting fluid, and under its own weight, presses out the saturated film of juice that coated each berry in solution. You can experience this sudden gravity effect by staying in the bath once the plug is pulled; noticing the loss of buoyancy as the water recedes around you.
Both tanks should be left like this for 1-2 hours.
This gives one an opportunity to fine-tune. The drained juice can be cooled if needed, yeast nutrients can be added, and acid can be corrected. Oxygen can also be introduced. As this juice or wine is in this new tank, settling the heavier particle occurs whilst the desirable yeast stays in suspension.
Now it is time to return the juice. One should avoid high-pressure jets like a fireman's hose breaking and churning up the skins of the cap. Rather, a wide-bore, high-volume pumping should aim to flood the cap. With the cap completely flooded, it starts to rise through the juice/wine. Every berry will see fresh liquid pass it on its way up. No drainage channels can form, and here are the similarities to the French Press and immersion brewing. The rising cap is acting as a reverse plunger pushing new liquid past every berry. At the bottom of the now-drained juice tank, a layer of sludge/sediment will be left behind. This can be washed out. Thus, with every cycle of délestage, more and more unwanted components are removed.
So right from the very start of the fermentation, the fermenting wine is in a happy place. Oxygen is available to the yeast, green and particulate matter is removed early, all the yeast is kept in suspension, and every berry has the chance to contribute to the wine quality. Mechanical agitation, which is the primary cause of astringency and bitterness, is at an absolute minimum.
We have found that introducing this technique has really helped develop the silky mouthfeel, great colour, and fragrant nose in our Pinots.
So next time you deploy your French press, channel the spirit of délestage and take your coffee to the next level.
Cheers,
Dudley