Pressing Merlot

When to press red wine

When making red wine from grapes, you crush the grapes then ferment them. You leave the skins and pulp in the fermenting wine, for a time, then you press it and leave the solids behind. The amount of time will vary according to the style of wine you’re making. Three or four days, will yield a light bodied wine. A few weeks will yield a tannic, full bodied wine. A good full bodied wine requires top notch fruit, and since I don’t have detailed information on how my grapes were grown I decided to make a medium bodied wine, and pressed after a week.

Pressing Merlot in a bladder press on 10/20/07

Here you can see the bladder press I used to press my Merlot.

Using a bladder press

I loaded the fermenting wine, pulp skins and all, into a perforated cylinder. At first, “free run wine” flowed out of the perforations, leaving seeds, pulp and other debris behind. Later, I applied water pressure to inflate a rubber bladder that squeezed the grapes against the sides of the cylinder and “press wine” flowed out. Altogether, I got over eight gallons (30+ liters), which is more than I expected from my 100 lb (45+ kg) of grapes. I was going by the rule of thumb that 100 lb would yield 5 gallons (about 19 liters).

Pressed Merlot in 5-gallon carboys, press wine in the carboy with the orange handle and free run in the carboy on the right. 10/20/07

I kept the free run and press wine separate. The carboy on the left, with the orange handle, contains press wine, while the carboy on the right contains free run. It’s still fermenting, and I expect it to finish in another week. Once it starts to clear, I’ll rack into fresh containers for aging. At that point, I’ll have to decide if I want to keep the press and free run separate or combine them.

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2 thoughts on “Pressing Merlot

  1. Aaron

    Hi Errol,
    This is probably a silly question, but I’m a homebrewer with very little knowledge of winemaking. Is aeration a concern when pressing red wines? Is there a way of getting the wine into the press which minimizes this? Thanks, and keep up the great work, I really enjoy your posts.

  2. Erroll Post author

    Hello Aaron,

    I know exactly where you’re coming from! I began by brewing beer, and suffered a bit of culture shock when I started making wine. Don’t these guys know that you’re supposed to aerate before fermentation? Do they know what they’re doing? It turns out they do. The quick answer is that a small amount of oxygen is necessary for proper aging, and that tannin, sulfite, and yeast protect a red wine.

    Red wine is often pressed while it’s still fermenting, and the active yeast will consume the oxygen. Even if it’s fermented out, the young wine contains a large population of yeast.

    The tannin in red wine interacts with oxygen. These interactions bind the oxygen, rendering it harmless, and are necessary for the wine to age properly.

    Winemakers routinely add sulfur salts, like potassium metabisulfite (aka “sulfite”), that bind with oxygen.

    So there are some unique aspects to red wine that protect it, and a little oxygen is necessary. Emphasis on “a little.” Too much oxygen will ruin a red wine, and it’s important to be careful about aeration after pressing. You might have noticed that I keep saying “red” when I talk about the wine. White wine is pressed before fermentation, has very little tannin, and is handled more like a beer.

    Thank you for the kind words. After slogging through all the comment spam in the moderation queue, finding out that some people are interested in, or learning from, my posts really makes my day 🙂


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