Wine Making 101

Well, I seem to have covered sparkling wine 101 without ever explaining how wine is made in the first place! Mea culpa! So, here we go with wine making 101: 

The short course: The most important thing to know is that making wine is so simple it was discovered by accident thousands and thousands of years ago. I like to think of it as the world’s second oldest profession.

Someone, yea long ago, was saving a batch of grape juice. A few days later, he noticed it was getting foamy, and then a few days more and he had a different beverage altogether! Grape juice with a kick!

All you need to make wine is grape juice and yeast. And, yeast is everywhere, like bacteria. So I guess what I’m saying is that grape juice wants to be wine – that’s the good news. The bad news is that wine wants to be vinegar so professional winemaking requires a little intervention.

For red wine:  As you’d guess, red wine is made of dark skinned grapes. All the color and most of the flavor and texture come from the skins – the juice is clear. That makes these dark grapes quite versatile. They can make red, white or pink wine depending upon how long the juice and skins are in contact.

1. On harvest day (preferably), the grape clusters are run through a machine that de-stems them and breaks the berries open. The crushed grapes go into a fermentation tank skins, seeds and all. 

2. These days, most winemakers add reliable, cultured yeast rather than waiting for nature to take its course. 

What is fermentation? It’s a natural chemical reaction. The yeast consumes the sugar in the juice and converts it into alcohol and carbon-dioxide gas. When the sugar’s used up, usually about a week later, for reds, the fermentation ends naturally, resulting in a dry red wine. A little over half of the sugar will convert to alcohol, so if the winemaker wants to make wine that’s around 13% alcohol, he should harvest grapes that are about 24% sugar (although he also needs to monitor the acid, pH and, most importantly, flavor). 

3. The winemaker separates the wine from the skins in a press, which is like a giant strainer with a squeezing mechanism. 

4. Most reds need some barrel age, but it’s optional.

For white wine: The vast majority of white wine is made from white varieties. 

1. For the sake of delicacy, the grapes are crushed and pressed immediately after harvest, leaving only the juice to ferment. 

2. Once the yeast is added, fermentation can take several weeks because the juice is often kept cool to retain fruitiness. 

3. It’s quite common to bottle white wine, even some of the very best, without any barrel aging at all. It’s a question of style.

See how simple that is? Of course there are seemingly endless variables involved each step of the way, but there you have it – bare bones wine 101! 

For those who want to dig a little deeper: 

The harvest: Most winemakers would agree that the harvest decision is the single-most important decision they make in the whole year. Like the best chefs, the winemaker can’t excel unless he uses top quality fruit picked at just the right time.

Just like the tomatoes growing in your back yard, the grapes start out very tart and green. As the summer goes on they soften, change color and the sugar goes up as the sharp acidity goes down. So, once the grapes have changed color, in mid-summer, the best winemakers monitor each section of vineyard with increasing frequency until they decide to pick. The vast majority of grapes for table wine are harvested at between 20 and 26% sugar, which is quite a wide range. when you buy table grapes at the grocery store they’re usually between 15 and 10% sugar so these wine grapes are very tasty! Accounting for early and late ripening varieties the harvest can take up to 10 weeks. In the northern hemisphere it’s usually in September and October. 

For reds:  The day of harvest the grapes are crushed and stemmed and are fed right into a fermentation tank.  All of the color and most of the flavor, tannin, and additional body is extracted from the skins into the juice during fermentation.

Variations in technique: Some winemakers like to allow several days “cold soak” before adding the yeast. This allows the juice to extract color and flavor from the skins without picking up bitter seed tannins. Extracting seed tannin is inevitable because the alcohol acts like a solvent, but this technique minimizes it, especially when followed by early pressing. This refers to pressing before the wine goes dry. 

Other winemakers prefer “extended maceration” and may leave the wine and skins in contact for a month or more! The theory is that the tannins polymerize (form a chain), which softens the mouthfeel. 

Cap management: Once the fermentation gets going, the carbon dioxide keeps pushing the skins up to the top of the tank to form what’s called a “cap”. It’s important to mix the cap back into the wine at least a few times a day in order to enhance color and flavor extraction. If it sits at the top too long it can dry and also get dangerously hot (fermentation produces heat). There are several methods used to keep the wine and skins mixed up. 

Pressing: When the fermentation is over, the wine is drained into another tank and the skins are sent to be pressed. The press wine may or may not be kept separate from the drained wine which is called “free run”. Good quality press wine improves the structure of the wine and also adds intensity. Too much press or the addition of “hard pressed” lots increases the yield, but also accentuates bitterness and astringency. 

Cleaning it up: The wine is often racked a time or two before it goes into barrels. This is simply allowing time for the grape solids and dead yeast cells to settle and them moving the clean wine off of them. That’s the first step in clarification. Racking continues in barrel and, eventually, the wine may be filtered or clarified in some other way before bottling. 

Barrel aging: With very few exceptions, red wine is barrel aged and often considerably longer than the whites. In addition to oak flavor extraction, the rather grapey tasting young wine evolves into something more complex and vinous. Tannic and angular characteristics soften and the components become better integrated. Evaporation loss concentrates the wine a bit. There’s an overall sense of mellowing and rounding.
For whites:  The grapes are perhaps crushed and certainly pressed on harvest day. Some wineries prefer to press whole clusters, so the grapes go from their picking boxes straight to the press (the theory is that whole-cluster pressing decreases astringency and increases fruitiness; it also decreases the number of suspended solids in the juice). In any case, only the juice is fermented. This is why the whites are lighter,  more delicate and lack astringency, compared to reds – the extracts from the skins give the wine extra body and the skins contribute tannin. 

Variations: Full-bodied whites, such as Chardonnay, may be fermented in a barrel instead of a stainless steel tank, which helps integrate the fruity and oak flavors. It makes the wine a bit richer. 

Some wineries put part or all of their Chardonnay through malolactic fermentation, which softens the acidity and creates a butter or butterscotch character. This takes a few weeks more, after the alcoholic fermentation is done. It can also be done in barrel, which helps with flavor integration. 

Barrel aging: Rich whites may be barrel aged, which concentrates the wine in addition to maturing it and adding oak flavor. 

Normally the wine is at least partially clarified before barrel aging. But, some winemakers allow the wine to age with the spent yeast cells in order to achieve a creamy texture. The wine can be stirred periodically to emphasize the effect. This is common for Chardonnay. 

TRIVIA! Up to 5% of the wine in barrels is lot to evaporation, annually. The loss is called the “angel’s share” and it creates work. The head space has to be topped up, periodically, to avoid spoilage (bacteria can form a film on top of the wine if it’s exposed to air). It’s common to do this about once a month in the production of fine wine. 

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