Before fermenting, make sure your grapes are at the proper Specific Gravity (SG). Another scale we would commonly use at this point is “BRIX”. If the desired Brix is too high, you can add water to get it down to the desired. If it is too low, add sugar to
bring to desired. Cane sugar is best as it is a cleaner product.
◦ Desired for Red wines are 1.10 SG or 24.5 Brix.
◦ Whites 1.095 SG or 22.5 – 23.5 Brix
Before starting, bring temp of crushed grapes to a general desired temp of 65 degrees to get yeast to work best. For best results during primary, try to keep a constant room temp at around 70-75 degrees.
◦ If you have trouble starting fermentation, the most common problem is a low temperature
◦ Follow yeast packet temp ranges
◦ White wines Start with 68 degrees
◦ Red wines Start with 72 degrees
◦ Once you’ve done a fermentation or two, go ahead and play with temperatures
◦ Remember that as yeast ferments, it will heat up your wine.
◦ Add a ‘starter’ at the beginning, then halfway through, add a second addition per nstructions.
◦ Add yeast nutrient within a day after pitching the yeast. Fermaid O is recommended at this time. Add 1 tsp per 6 gallons.
Repeat again when must (Fermenting grapes) get to 1.04 (SG)
Pressing grapes is done after primary fermentation. Most pressing is done when the cap drops, which is the visual method for figuring out when grapes can be pressed. This happens when the Specific Gravity drops below 1.0. At that point, your grapes may float some but there is no longer a real cap being formed.
Pressing before the cap drops can often result in a slowed fermentation. Also, the wine may not be as dark or as tannic as it could be if left to ferment until the cap drops. There is no absolute answer to ‘Too Soon’. Press your grapes when you would like, but the best quality wines are usually left to ferment completely and they will tell you when pressing can be done.
It is very easy to leave pressing until it is too late. Once fermentation is essentially finished and the cap is dropped, there is not enough carbon dioxide at the surface to protect the wine from oxygen. There is also a substantial amount of yeast husks and other organic material that will begin to rot once fermentation is finished. At that point, the wine will spoil very easily.
As the yeast starts to work, the gasses produced will push the grape skins to the top. You will need to knock or punch this 'cap' down 2-3 times per day. Remember, the flavor and aromas are in the skins!! Continue this religiously until the cap has sunk and you have liquid on the top and it's time to press.
If you choose to use a starter to encourage the Malolactic process (Red grapes have a natural stringent acid called Malic. This acid can be tamed by converting the malic to a Lactic acid by introducing the malolactic culture. The wine will generally go thru it on its own but at its pace. We really want to control as many aspects as we can to get all our steps to the process in.The conversion to Lactic will give the wine that smooth buttery feel. At about the 1.04 area you can add a Malolactic Culture (Make sure you purchase this a couple weeks before you get your grapes. It is usually harder to find when everyone is fermenting their grapes).
Once the wine is pressed, let sit for no more than 48 hours and rack!!!. The yeast husks and other matter will spoil your wine in a hurry. Left too long will give you the Rotten Egg smell/flavor. Re-Rack 5-7 days later!! This is the biggest error winemakers can make by letting this step fall into the hands of procrastination.
Most winemakers would not recommend stopping a fermentation. It's usually better to allow the fermentation to complete and, then add juice saved off before primary (back sweetening) or add sugar to bring the sweetness up to the desired level.