Welcome to the fourth part of the series Winemaking for beginners: From grape to glass. So far we have looked at what wine actually is, how soil and climate shape it, and which grape varieties are the raw material of wine. Now we head out into the vineyard, just as it all comes to a head.
The harvest is the big moment of the year. This is where a whole year's work with sun, rain and patience turns into baskets full of grapes that are to come in and be transformed. In this part we follow the journey from the ripe bunch hanging on the vine to a batch of must standing ready, prepared to become wine.
What you will learn
- When and why the grapes are harvested at the right moment
- The difference between harvesting by hand and by machine, and what it means
- How the grapes are pressed, and what must actually is
- How the must is made ready for fermentation
When are the grapes harvested?
Timing is everything. A grape picked too early tastes green and sour and makes a thin wine. A grape that hangs too long loses its freshness and becomes flat and overripe. The winemaker is looking for the balance, the point where the grape has gathered enough sweetness while still retaining a fresh acidity.
You can think of it a little like fruit in a bowl at home. An unripe peach is hard and sour, an overripe one becomes mealy and dull, but at just the right moment it is juicy and full of flavour. It is the same with wine grapes, only with even greater significance for the finished result.
Every day leading up to the harvest the winemaker tastes the grapes and keeps an eye on the weather. A few days of sun or rain can shift the decision. That is why the harvest is rarely planned far in advance, it takes place when the grapes are ready.
Hand harvest vs. machine harvest
Grapes can be harvested in two ways, and the choice leaves its mark on the wine.
Hand harvest
With a hand harvest, people pick the bunches by hand and place them gently into crates. It is slower and requires many hands, but it is gentle. The pickers can sort along the way and leave bad or diseased bunches behind. On steep slopes and in vineyards with narrow rows, hand harvesting is often the only option. The result is whole, undamaged grapes that arrive at the cellar in fine shape.
Machine harvest
A harvesting machine drives over the rows and gently shakes the grapes off the vines. It is fast and efficient, and large, flat vineyards are well suited to it. On the other hand, the grapes are handled more roughly along the way, and leaves and twigs can come along. Machine harvesting is best suited to vineyards laid out with that in mind.
Neither method is wrong. It comes down to the landscape, the grape and the style the winemaker is aiming for.
Pressing and making the must
Once the grapes have come in, the juice needs to come out. First the bunches are typically destemmed, so the stems are removed. The stems make up only a small part of the bunch, but they can give the wine a bitter, austere note, and that is why they are usually sorted out.
Then the grapes are lightly crushed, so the skin bursts and the juice runs. The juice that runs off on its own, with no pressing at all, is called free-run juice and is considered the finest part. It makes up about a third of the total juice. The rest is gently pressed out of the grape mass.
The pressing itself is done gently. A gentle press squeezes softly and evenly, so the skin is not torn and the seeds are not crushed. This is important, because the seeds contain compounds that can give the wine a hard, bitter taste, and you would rather leave those undisturbed.
The result of it all is must, the fresh, sweet grape juice that is the raw material of all wine. Must from ripe grapes is sweet and fragrant, and it is this juice that, in the next step, is transformed into wine.
Preparing the must for fermentation
Before fermentation gets going, the must needs to be made ready. It comes down mainly to two things: keeping it clean and finding the right balance.
Fresh must is vulnerable to oxygen. If it gets too much air, it can start to turn brown, a little like a cut apple left out. That is why one works quickly and gently from grape to must, so the juice keeps its freshness and bright colour.
The must also contains small floating particles from skins and pulp. A suitable amount helps the fermentation get off to a good start, while too much can cause problems along the way. That is why the must is often allowed to settle a little, so the coarsest parts sink to the bottom before fermentation begins.
Here also lies the first big difference between the colours of wine. For white wine, the juice is typically separated from the skin quickly, so it stays clear and fresh. For red wine, on the other hand, the juice is allowed to draw flavour and colour from the skin, for it is precisely in the skin that the red colour is hidden. But that is a story for later in the series.
In brief
- Grapes are harvested when they have the right balance between sweetness and fresh acidity, not too early and not too late.
- Hand harvesting is gentle and allows for sorting, while machine harvesting is fast and suits flat, open vineyards.
- The grapes are destemmed and lightly crushed, after which the juice is gently pressed out, so that seeds and stems do not impart bitterness.
- The result is must, the sweet grape juice that is the raw material of all wine.
- Before fermentation the must is protected from oxygen and allowed to settle, so it is ready for the next step.
Frequently asked questions
What is the difference between must and wine?
Must is the fresh, sweet grape juice you get out of the pressed grapes. Wine only comes into being when the must ferments and the sugar turns into alcohol. Must, then, is the starting point, wine is the result.
Why are the stems removed from the grapes?
The stems can give the wine an austere, bitter note. By removing them before pressing you get a cleaner and softer must. In some styles, however, the winemaker chooses to deliberately keep some of the stems.
Ready for the next step?
Now the must stands ready, and so it is time for the transformation itself. In the next part, Fermentation: How must becomes wine, we look at the moment when the sugar turns into alcohol, and the juice truly becomes wine.
By all means take your time to taste your way forward and notice how different wines speak to you. Remember that the best pairing is the wine you like with the food you like. Do drop by our selection and let your curiosity be your guide.