The Backyard Vineyard – Managing the Must

You built your backyard vineyard. You planted some vines. You trained them up the trellis for a year or two, harvested some grapes, and finally had the chance to crush them with family and friends on harvest day.

You now have a large, stainless steel vat full of soupy, crushed grape juice. Now what do you do?

At this point, the science of growing the grapes shifts to the art of making wine. And like any art or craft, your product may be quite sloppy as a beginner, and that’s perfectly fine.

Unless you really screw something up, for the most part, the wine will be “drinkable”, which is sometimes a nice way that family and friends can express their appreciation for a homemade product that is otherwise less than satisfactory in taste. And that’s what makes homemade so special – sometimes, it can make the mediocre more marketable.

Managing the Must

As we briefly outlined in our previous post, you need to check-in on the grape must about twice a day for the next month or so. The first month post-harvest, more or less, will involve the following tasks (for simplicity, we are focusing on red wine, as we’ve focused our winemaking on red wine for the most part):

Day One

1. Stem and crush grapes into fermentation vat (given our affinity for Georgia and Georgian wine, we tend to leave about 1/3 of the stems in the must for a deeper, darker flavor and wine).
2. Test Brix and pH – write these down in your vintner journal (these numbers should align with the ones you took to determine ideal harvest ripeness)
3. Add potassium metabisulfite if necessary/desired
4. Adjust sugar, if necessary (i.e. add sugar if your sugar readings are below 20 Brix)

In previous posts, we already discussed stemming/crushing the grapes, as well as testing Brix and pH to determine ripeness.

Let’s take a look at adding sulfites and sugar – two key decisions on harvest day.

Adding Potassium Metabisulfite

Oxygen spoils wine. Much like an apple with a bite taken out of it, the process of oxidation (contact with oxygen) will cause the exposed fruit to brown and eventually spoil.

A simple, easy way to prevent this from happening is by adding potassium metabisulfite, or “sulfites”, to the must so that a gas heavier than oxygen is emitted from the must, protecting the wine from contact with oxygen long after the primary fermentation has ceased to produce carbon dioxide (also heavier than oxygen). Imagine a thin, invisible cloud that sits at the surface of the wine, protecting it from contact with oxygen.

There are a wide variety of calculations and theories on this, and there are even those (especially in Georgia) who prefer to NOT use sulfites at all. (Georgians claim this is why their natural/homemade wine doesn’t produce a hangover.)

However, for those who want to play it safe and don’t plan to drink their wine immediately, you should probably add some sulfites. Adding chemicals, after all, is the American Way.

We like to keep things simple, so here is our recommendation (and so far, so good – no spoilage):

If your pH is reading 3.2 and 3.5, which it should be if you timed your harvest correctly, you should add no more than 40-50 ppm of potassium metabisulfite, which amounts to no more than 2/3 to 1 full Campden Tablet per gallon of must.

All you need to do is take out a old-fashioned mortar and pestle, grind down your tablets, dissolve the powder in some tap water, and then thoroughly stir the dissolved mixture in to the must, so that it is distributed as evenly as possible.

Adding Sugar

Sugar feeds yeast, and yeast creates alcohol. Alcohol is desirable not only for the side-effects produced from consumption, but also as a preventative measure to protect the wine against unwanted spoilage, disorders, and other complications. If your alcohol content is too low, not only will the wine taste soft and dry, but it has less natural armor to protect itself from infections.

The ideal alcohol percentage is 12.5% for a solid wine. So, following the rule that the alcohol percentage of the finished wine will be a little more than half the Brix of the must, this means you should probably add sugar to any must under 20 Brix. (In a hydrometer reading, this amounts to anything under 1.081.)

Determining Your Sugar Adjustment

Specific Gravity of Must	Sugar in the Must (Grams/Liter)	Brix
1.047	124	12.0
1.051	135	13.0
1.055	145	14.0
1.059	157	15.0
1.063	168	16.0
1.068	178	17.0
1.072	188	18.0
1.076	201	19.0
1.081	213	20.0

So, all you need to do is break out your hydrometer, get a clean sample of your must (strain it before adding to the hydrometer, so there aren’t any “floaters” impacting your reading), and pull your specific gravity.

For example, let’s say you pull a gravity of 1.068. Most hydrometers these days will also tell you that this will produce a final alcohol content of 9-9.5%, which is not ideal.

Using the above table, you know that this amounts to 178 grams of sugar per liter of must.

(As a rule of thumb, an ideal, 12.5% finished wine will have a must with 1.088 specific gravity, or 230 grams of sugar per liter.)

Using the 12.5% wine as our target, we know that we are short 52 grams of sugar per liter (230g – 178g = 52g). If you then multiply the grams per liter you are short by the total number of liters of must you’ve just harvested, you’ll arrive at the total amount of sugar, in grams, you need to add.

For example:

My hypothetical 5 gallons of must converts to roughly 19 liters.

If I am short 52 grams per liter of sugar based on the above scenario, that means I need 19 x 52 grams of sugar, or 988 grams of sugar. A thousand grams is a kilogram, which is equal 2.2 pounds when speaking science in America. So I need to add just under 2.2 pounds of sugar to my must to reach that 12.5% finished alcohol content.

And three final notes:

1. Most winemakers agree that pure, white table sugar is best for this task.

2. Don’t just dump the sugar into the must. Ideally, you will warm up some water/must juice on a cookstove, as the sugar, and then gently stir to dissolve. Once dissolved, let it cool down a bit before adding to the must.

3. If you are the kind of person who checks nutrition labels for “added sugars”, as you should these days, and this whole process bothers you, please know that none of these sugars will end up in the finished wine, unless you manually stop the fermentation process to produce a sweet wine with residual sugar. In other words, the yeast will devour all of this “added” sugar, converting it to alcohol, and making your wine stronger, safer, and tastier.

Once your grapes are crushed, your desired amount of stems removed, your sulfites added, and your sugars adjusted, throw a towel over your primary fermentation vat (to protect against fruit flies), move to a cool, dark place (basements are great), clean up all your gear, and enjoy the rest of your day. Tomorrow, you’ll add the yeast and the real fun will begin.

Day Two

• Add the Yeast

Congratulations. You’ve made it to Day Two of your one-month winemaking initiation. Your main job today is to 1) ensure there are no fruit flies attacking your juice, and 2) add the yeast.

Adding Yeast

There are a wide variety of yeast options out there, but to keep things simple, as we like to do, we recommend Red Star, otherwise known as Montrachet, as it can be shipped quickly on Amazon, provides solid red flavor, and is widely available and popular.

Like your sulfite and sugar, do not just dump the yeast into the must. Dissolve the yeast in lukewarm water (NOT hot water, which can kill the yeast), pour it into the must, and then stir and mix thoroughly.

Packets like the above example are best, as they provide detailed quantity instructions, contain batch expiration dates, and are sufficient for the backyard vineyard enthusiast in terms of quantity.

At this point, you are all in. Within the next 24-48 hours, your juice should begin “roaring” – bubbling will be visible, gases will be audible, and the vat will feel very alive. It is very exciting after all those months of tending the grapes.

Days 3-26 (Primary Fermentation)

• “Punch down the cap” twice a day
• When fermentation slows (i.e. bubbles begin to settle down), test the Brix – it should be reduced by about 2/3
• Consider “extended maceration” for red wine

Fermentation Temperature

At this point, you can experiment with a variety of fermentation techniques. Your first decision as a backyard vineyard enthusiast will be where to physically ferment your wine, which will directly determine your fermentation temperature.

Cooler temperatures, such as in the 50’s (Fahrenheit), can lengthen/delay the fermentation process, allowing it to last several weeks in most cases. Warmer temperatures, such as the upper 80’s and lower 90s, can result in a three-day finish.

As a backyard vineyard winemaker, your actual fermentation vat won’t overheat the way the massive commercial ones do, so choose your fermentation location based on the external temperature, knowing that the vat will heat up only very slightly in the process and won’t require any external cooling.

At the end of the day, you won’t have much choice – you’ll really be at the mercy of your room temperatures. So, unless your family is willing to forgo heat for the winter so that you can experiment with a cool-temperature primary fermentation (please don’t be that guy), you should probably just stick with an upper 60-degree, low 70-degree room that doesn’t swing in temperature from night to day. Closer to 80-degrees is probably the ideal for red wine, whereas mid-60s is the ideal for white.

Punching Down the Cap

With your yeast added and your fermentation location selected, your job now is to check-in on your juice twice a day, observing the peak and fall of fermentation while also punching down the cap.

Punching down the cap is pretty simple – with a clean hand/arm, or a sanitized, large soup spoon, reach into the fermentation vat and gently mix and swirl the soupy mixture so that the dried, floating material on top (the “cap”) is pressed back down into the liquid.

The whole point here is to keep all the must, both solid and liquid, mixed together and coated in juice so that no unwelcome bacteria begins growing on top, on the “crust”. In fact, you don’t want any crust to form at all, which is why you are stirring it twice a day.

A second benefit of this ritual is so that you can observe the fermentation in action twice a day, up close and personal. You should take notes – you’ll be able to see and smell when the fermentation has peaked, when it begins to wane, and even likely when it is done.

If you suspect it is done, or nearly done, measure the Brix – it should have reduced by 2/3. That is your signal to switch from primary to secondary fermentation, as the juice is now at risk of oxidation at this point with less carbon dioxide being produced naturally.

Skin Contact

Bottom line up front: if you want fruity, light, quickly drinkable red wine, reduce the amount of time your juice swims with stems and skins. Press early, and with only a third or so of your Brix reduced in the primary fermentation vat when you rack to the secondary fermentation vessel. (For example, if your must begins with 21 Brix, you’ll press and rack to a secondary fermentation vessel once it hits 14 Brix, allowing the fermentation to finish in a clean, skin- and stem-less environment.)

If you want big, bold red wine that requires additional aging for flavor, you’ll want to lengthen, both naturally and manually, that skin and stem contact time. Your primary fermentation with your skins and stems could take upwards of three to four weeks. This is likely well beyond the initial fermentation, and can only be achieved through a process known as extended maceration.

Extended Maceration

Maceration, by its very definition, is the process of allowing grape skins to sit and soak in the must. Extended maceration is just a method in which we extend this process as long as possible, both naturally and manually.

The benefits of this process to red wine cannot be understated – complex flavors, deep, dark colors, and more diverse aging possibilities can only be achieved when you allow the skins to really break down over time in the must.

The way to achieve this in your standard basement or living room is pretty simple. Once you observe the fermentation shifting from the initial rolling boil to a light fizz, do the following:

1. Go to a local brew shop and purchase a small tank of carbon dioxide along with a siphoning hose from your local hardware store.
2. Duct tape a plastic trash bag or something similar to the primary fermentation vessel.
3. Poke a hole in the plastic to allow carbon dioxide to escape slowly.
4. Twice a day, when you punch down the cap (you’ll now have to remove the plastic to do so), feed the siphon hose into the small hole and release a few seconds of carbon dioxide into the plastic (but not into the must). This will provide your juice, now exposed to the elements as fermentation wanes, with a twice-daily protective cloud of carbon dioxide so that maceration can continue even as fermentation stops.

After 3-4 weeks, the “cap” (the floating skins and stems) will suddenly sink to the bottom of the vessel. That is your cue to shift to the press and secondary fermentation.

Up next, we will discuss the press, secondary fermentation, and bottling.