Winemaking 101 – Episode 4 – Fermentation & Pressing

So far we’ve gotten the grapes, crushed them, and detoured into my acquisition of a grape press. Now it’s time to inoculate and get onto the fermentation!

Years ago I kept my wine and beer notes in a small, red 6-ring binder. I moved all my notes to my original web site, and haven’t used the book in years.

Original Notebook

Although I’m posting my notes on this site, I’m recording in my book as well. [The notes in the picture are from 1987.]

Fermentation isn’t all that exciting. It has a distinct aroma (that my wife hates) but there’s little activity.

Dave Bagley (the owner/wine maker of Poplar Ridge Winery on the Seneca Lake Wine Trail, Hector NY, who sadly passed away some years ago) told me something profound:

We don’t make wine. It makes itself. Practice ‘benign neglect’. Guide and correct the wine, but leave it to do it’s own thing.

This is not an exact quote, but it’s as close as I can remember, and it carries the spirit of what Dave told me.

So I add yeast and a few additives, keep everything hygienic, and let the wine do it’s thing.

Fermenters in action

BTW — the grapes are not shy … the towels let air in, keep insects out, and keep the heat in. A drop in temperature can stun the yeast and stop fermentation.


Adding yeast is not a requirement. Yeast grows on the skin of the grapes, and left alone, grapes turn into wine. Unless the juice is boiled (or otherwise Pasteurized), it’s gonna ferment!

This begs the question — then why add yeast?

Because we don’t know for sure what yeast is growing on the grapes. There are thousands of varieties of yeast, and only some produce good wine.

Great wineries that have existed for decades or even centuries may not add yeast. A strain of yeast grows in their vineyards and is embedded in the wood of their fermentation areas has stamped out other forms of yeast and produces the same consistent quality each year.

For home wine makers? We don’t know what yeast is on the grapes we buy, so we use a commercial yeast that has the property of killing off wild yeasts. This way we produce a consistently good result.

Commercial yeast strains typically have a “killer” feature — they crowd out or even kill other yeast and bacteria which prevents something nasty from taking hold. For me, this is a key factor.

I’m not going into detail on yeast varieties. As much as I know about yeast, I’m still not qualified to go into a detailed explanation … unless you’re suffering from insomnia. In that case, I can help!

Suffice it to say I purchased Red Star Premier Rouge as it produces the characteristics I want. I added 2 packages to each fermenter Sunday, and decided to add a third one on Monday. Each package is good to start 5 gallons of wine … but I thought I might have enough wine that a couple of extra dollars was a good investment.

Soak the yeast in a cup of 95 F water for 15-20 minutes, then pour it (water + yeast) into the fermenter.


Grapes are the perfect food for yeast as they contain everything yeast needs to grow and thrive.

However … sometimes nature needs a bit of a boost. So we add grape nutrient to ensure it has everything for optimal growth, and add an energizer (Red Bull for yeast) to kick start the growth.

So I added a product called Fermax to ensure my yeast will get off to a get start!

Pectic Enzyme

If you’re making fruit (non-grape) wine, pectic enzyme is often a must. It causes fruit pectins (which makes jelly gel but can prevent wine from clearing, leaving it hazy) to break down. Grapes supposedly don’t have pectins but many authorities state that it helps with color extraction from the skins.

I had most a bottle in the fridge, so I had nothing to lose by adding it. It’s a year+ old and supposedly has a long shelf life if refrigerated, but I added it anyway. It doesn’t hurt.


Wine has a fair amount of acid in it, typically tartaric, citric, lactic, and malic. Without acid, wine is flat tasting and has a shorter shelf life. The yeast likes a certain pH range so we test the wine and make corrections.

This is my first time doing West Coast grapes. My previous experience is mostly with Finger Lakes (NY) grapes and some NC grapes. Both tend to be high in acid is steps need to be taken to reduce acid.

Not so with West Coast grapes — they are often low in acid. All three of mine are case in point — really low acid. So I correct with acid blend, a mixture of tartaric, malic, and citric acid. I didn’t add it before I inoculated, which was a mistake. I’ve been stirring 1 tsp into each wine each day as too much at once will change the pH too rapidly, which can stun the yeast.

Once fermentation is done I will both check pH and do an acid titration (which I suck at). I expect to add a lot more acid blend before I’m done.

Oak Chips

I added heavily toasted American oak chips to the Merlot & Zinfandel, and medium toasted French oak chips to the Malbec prior to fermentation. The developing wines pull flavor and aroma from the oak, which can be beneficial for red wines.

American, French, and Hungarian oak all have differing characteristics. Some wine makers age different batches of wine from the same grape and year in different oaks, then blend them before bottling to get the characteristics desired.

I had 1 bag of French oak and 2 bags of American, so I flipped a coin for which went into which wine.

Once fermentation is done and the heavy lees has been racked off of (in English, siphon the wine off the thick layer of sediment that has built up, dead yeast cells and grape solids) I will add Hungarian oak cubes to each carboy to add more oak flavoring.

<h4>When to Press?

Wine makers use a hydrometer to measure the specific gravity (SG) of wine. Float the hydrometer in a sample of wine and read the scale at the surface of the wine.


I like to press when the wine is at 1.010 (a small amount of sugar remaining) but have pressed as high as 1.020.

A dry red wine typically has a SG ranging from 0.990 to 0.996.

Press in Action

How to Press?

Line the press with cheese cloth. This is not required, but it keeps most of the pulp and seeds from exiting the press.

Next dump the must (wine in progress) into the press, being sure to not dump in so much at one time that it overflows the press.

Press in Action 1

Keep adding must, a bucket at a time, until you either run out of must OR fill the press to its capacity. My press can hold more than 5 lugs of grapes — I’m guessing it can handle 7 or 8, so we dumped all the must from a batch in.

When done, fold the cheesecloth over the grapes and add the pressing blocks:

Grape Press Blocks

Depending on the fullness of the press, add more blocks on top. The rachet that exerts the pressing force cannot go below the barrel top, well, not on presses designed like mine. We we add alternating layers of blocks, like this:

Press with all the Blocks

This is the first run wine, so I’m not pressing hard. I got 11.5 gallons Zinfandel, 11.5 gallons Merlot, and 13 gallons Malbec. Note that some of the volume is dead yeast cells and grape solids, so the final will probably be 1/2 to 1 gallon less.

Stay tuned for Episode 5 — What Is A Second Run Wines?