Hello and welcome to Wine Education: Wine Making 101. Here I’m going to do my best to simplify the process of winemaking.
Let’s have a look at some parts of the grape. There’s the stem, the skin on the outside, the pulp (or flesh) on the inside, and the seeds.
The stem contains some tannins. The skin also contains tannins, color, the tannins, and a lot of the flavor as well. It's also where the phenols come from. The flesh gives the juice the wine is made of. And finally, the seeds inside have bitter oils in it.
Grapes can be picked up through a machine, which goes down the middle of the vines and shakes the vines, getting the grapes to fall off into a bin.
They can also be handpicked clusters. This is a technique mostly used in small production, better quality wine. It protects the grape and keeps it from bruising.
Red wine is made red through contact with the grape skin. (This means you can actually make white wine from “black grapes” if you remove the skin, but red wine can’t be made from white grapes).
Imagine this conveyor belt that has a ton of grape clusters on it. There are people pulling out things that you don't really want in the line, such as leaves or rocks.
Before going into a fermentation tank, the grapes need to be crushed. It's actually a gentle press, so some of the juice comes out on the side and the inner part of the grape is exposed. After all, grapes have been gently crushed, they can go into the vessel.
The vessel - from oak or stainless steel - gets filled all the way up. The way this turns into alcohol is through a yeast-driven fermentation. The yeast eats up all the sugar from the grapes and starts releasing CO2 (carbon dioxide), which then turns into alcohol. Then the bubbles from the CO2 will push the grape skins to the top of the vessel. This is called maceration.
Maceration is kind of like soup. If you think of soup sitting in a pot, you got all the ingredients while some of them are simmering, some on the top. And you're letting it soak up all those flavors. It's similar to wine.
So, skins are starting to rise to the top, and what’s next is to push those skins back down into the juice, that way it continues to add the color, flavors, and tannins. You can:
This process can take from 2 to 4 weeks. Or lighter styles can take only 5 days.
Once maceration is done, what we have is Free-Run Juice and Pressed Juice.
Free-Run Juice is the juice that comes out naturally from the weight of the grapes, so it hasn’t been pressed out. Winemakers typically take this juice and separate it in one vessel. The leftovers will be pressed-down, and almost like a French press, they will squeeze out whatever they can of the leftover juice with the skin. That’s the Pressed Juice.
These are almost always put in separate vessels. The reason is that the free-run juice tends to be lighter, with a lot more fruit. The pressed juice has way more tannin, complexity, and is kind of bitter and harsh just because of all that’s coming from the skin.
Then, these two will usually be blended together to make the final red wine. So complexity, character, structure, and tannins from the pressed juice - and fruit, lightness, and freshness from the free-run juice. The ratio is typically nine to one, so 90% or so of free-run juice, and 10% of pressed juice. Of course, this could vary depending on how much of the tannin structure the winemaker wants to go into the wine.
The mix goes into oak barrels. Oak adds more complexity and character to the wine. Stainless steel is pretty much gonna just preserve what the wine is after fermentation.
There are varieties of oak:
Had those wines gone into a stainless steel tank, (which is a closed, oxygen-free vessel), there’s not going to be much aging there.
Once it goes into the bottle, there’s something called "bottle shock". There are going to be big shifts in the wine. If properly sealed, it is totally cut off from oxygen. What can happen depending on how long red wine is aged in the bottle?
The fruit tends to kind of fade a little bit, and the tannins soften a little bit as well. You can then have a really beautiful, well-rounded wine. If it's a poor-made wine or it's a different winemaking style, and there's not enough fruit in it, you end up left with - if it ages too long - you end up with just hardly any fruit and a lot of the other characteristics that can come from bottle age, such as wet-like leather and mushrooms, which can be good if it's a deliberate process… but it can be really gross if it's a bad process.
A winemaker wanted to create a wine that was lighter, smoother, easy-drinking, and approachable. For that, there’s something called carbonic maceration.
The difference between maceration as I explained before and carbonic maceration is that they take the whole clusters, and they don’t crush them. The grapes are still intact, and then they create a carbon dioxide environment, usually from a pump at the bottom of the vessel.
Regular fermentation is yeast eating the sugar, creating CO2 and alcohol.
With this technique, CO2 creates heat, which then causes an intracellular fermentation inside the grape. So the grapes start to ferment inside eventually causing them to burst open. Through this process results a very low-alcohol wine of maybe 2% to 2.5%.
After this, secondary fermentation is done. This secondary fermentation is a yeast-driven fermentation. The reason for this is to bring up the alcohol level. After all, I don't know anybody that's gonna drink 2 - 2.5% alcohol wine! Do you?
Once fermentation is done, the rest of the procedure with free-run juice and pressed used is the same.
White winemaking is very similar to red winemaking. The main difference being separating the skin. Grapes are crushed, the skin is separated and then goes into a vessel (oak or stainless steel).
Then the process of the yeast eating up the sugar begins, turning it into carbon dioxide, bubbles, and… white wine.
White wine like Chardonnay and Sauvignon Blanc - and sometimes Viognier - undergo malolactic fermentation.
It’s actually not “fermentation”. It's more malolactic conversion, "MLF" or "Malo". You may have heard these terms before.
Essentially it’s where the malic acid (which is the very acidic tart acid that you would find in an apple) is converted into a softer, creamier acid of lactic acid. This is done through a "secondary" fermentation process, where the winemaker will inoculate a certain bacteria that creates a reaction. Other winemakers choose to do this during the initial fermentation process. Others choose to do this when the juice is taken and put into its maturing vessel.
One of the main reasons the winemaker does this is to help de-acidify a wine. In cool climates wine is super acidic. If you're looking for something that's a little smoother or creamy, you would inoculate malolactic fermentation to create that.
There's a process called "racking" in which the dead yeast cells and the juice are put it into an oak barrel, and that yeast is gonna create a toasty, bready flavor. Red wine also has malolactic fermentation. However, it's a little less notable just because it's not typically
inoculated like this, creating a buttery feel, but to help bring down the acidity in certain red wines.