Wine Making Tutorial – Lesson 2B (Wine from Wine Grapes)

Wine Making – Preparing Your Wine Must or Juice (Grape Wines)

A couple of items to point out before we talk about preparing/processing your grapes:

  • White wine is fermented without the skins, unlike wines from fruit and its red grape wine counterpart, white wine grapes after crushing are pressed to extract the juice and the skins are no longer used and not included during fermentation.
  • Native Wild Grapes such as Muscadine, Fox and Frost tend to have high acid levels and lower sugar levels, both needing adjustment prior to fermentation by adding water and additional sugar.
  • Native Wine Grapes such as Concord, Niagra, Catawba and Deleware tend to be a bit high in acid, not as high as wild grapes, and higher in sugar content than wild grapes.
  • European Wine Grapes such as Cabernet Sauvignon, Pinot Noir, Merlot, etc. are grown specifically for wine making and may or may not need some adjustment to sugar and acid levels prior to fermentation. However, when adjustments are needed the adjustments are typically quite small.
  • In short, some grape juices need to be diluted with water to lower their acid levels and or to reduce their excessive flavors. Some need sugar added because they lack enough sugar to ferment to the desired alcohol level, others need sugar added because diluting with water to reduce acid and or excessive flavor results in not having enough sugar. Additionally, not every grape contains the same amount of acid or sugar, either grape to grape or season to season so you may want to adjust your acid and sugar levels up or down prior to fermentation by adding additional sugar or water in addition to what your recipe calls for. This will control you post fermentation alcohol level.

Processing/Crushing De-Stemming Your Grapes:

  • Crushing the grapes breaks the grape skins allowing the juice to flow from the grape. Crushing should be done with a minimum of grinding and tearing which is why using food processing equipment is not recommended as it will result in excessive, unwanted bitterness and astringency from the skins.
  • De-Stemming is required for red wines. If the stems were left in with the grapes as part of the must during fermentation it would result in excessive unwanted bitterness and astringency. However, removing the stems from white wine grapes is not necessary since white wine is not fermented on the skins. NOTE: Do not be fearful of a few stems being missed and left in. A few left in are expected and your wine will be just fine.
  • If you are making a very small quantity of quantity of wine, a gallon or two, plucking your stems by hand will serve two purposes, obviously de-stemming, and typically if you are rough enough while plucking/de-stemming you will break enough skins to have fulfilled the crushing that is needed.
  • If you are crushing and de-stemming grapes for say a 5 gallon batch of wine you may want to automate a little. If you are using wild grapes you may be working with 20 to 40 pounds and if you are making a batch from European wine grapes you are probably working with 60 to 80 pounds. The following is just one method and is good for quantities up to 200 to 300 pounds:
    • Place a cleaned plastic milk crate on top of a new and cleaned 32 gallon trash can, large ice chest, or other similar container that can hold the milk crate and catch the juice and pulp that will be created.
    • Place a few pounds of grapes in the milk crate and smash the grapes through the bottom of the milk crate using two hands or a clean board. A washboard type scrubbing motion works well. This process will send your juice and grapes into the container below leaving the stems in the bottom of the milk crate to be discarded.
    • Not all the grapes will be broken leaving some whole grapes falling through. This is okay. Most mechanical crushers only do not break every grape either and some whole grapes are desired during the fermentation process.
    • Be sure to wear rubber gloves during this process, the stems are rough on the hands, the red grapes will stain your hands black, and the tannins in the grapes will dry out your skin. Needless to say as romantic as the notion is of crushing grapes with bare feet, it is not very practical and can be quite painful leaving you with black stained feet with dried out cracking skin.
  • Mechanical Crushers and De-stemming
    • Most home wine makers making wine from grapes use a mechanical crusher; the most common and affordable is the hand crank crusher. These machines make processing grapes easy and manageable and removing the stems after crushing is a fairly easy task if needed for your red wine.
    • There are of course larger more expensive Crushers De-stemmers available that are available as manual or electric motor driven.
  • If you are making white wine from grapes and pressing prior to fermentation go to the next Tutorial on Primary Fermentation where we discuss pressing of grapes.
  • After Crushing and before starting fermentation, as mentioned above, it is time to adjust your acid and sugar levels.
    • Take an acid reading using an acid test kit or acid test strips.
    • Pre-fermentation acid levels for white wine should be 0.7 to 0.9 percent and red wines should be about 0.7 percent to obtain a finished acid level in both reds and whites of 0.6 to 0.65 percent. May winemakers prefer slightly higher acid levels in sweeter white wines to balance the residual sugar.
    • Add Tartaric Acid if your acid level is low or add water to reduce if the acid level in your wine must is high
    • Winemakers always want to know the PH level of their wine musts. The PH level is a measure of the concentration of hydrogen ions in the must and basically a measure of the strength of the acidity. Remember, the lower the PH the more acidic the wine, the higher the PH the less acidic the wine is. The PH should be between 3.2 and 3.6, the lower number being more acidic and sour. 3.3 to 3.5 is preferred for red wines and 3.2 to 3.4 for whites. Most home winemakers do not have the ability to control the PH level once the grapes have been picked and can only control it in as much as it will raise and lower with the adjustment of total acid, but it is worth knowing if your grapes are where they should be.
    • Take a Hydrometer Reading, white wines depending on the variety are typically between 21 and 23 Brix and red wines are typically 22 to 25 Brix
    • If your Brix Reading or Potential Alcohol Level is lower than you want, add sugar (ordinary table sugar is just fine). If your Brix Reading or Potential Alcohol Level is higher than you want, add water.
    • Keep in mind if you have to add water to reduce your sugar level you may have to add Tartaric Acid. It is best to measure both Total Acid and Brix prior to making either adjustment as an adjustment for one may take care of the other or result in a second and unnecessary adjustment.
    • To help know how much sugar or water to add you can check out our Brix Chart
  • Before fermentation you will also want to add the following
    • Pectic Enzyme (Helps break down the fruit - Red Wine Only, or the rare instance when you ferment a white wine on its skins)
    • Potassium Metabisulfite (Preservative)
    • Yeast Energizer or Yeast Nutrient (Food for yeast that helps guarantee healthy and complete fermentation)

Subsequent and Previous Wine Making Lessons:
Winemakers Depot - Your Trusted Source for Wine Making Supplies, Wine Kits, Beer Kits and Homebrew