As the wine harvest approaches, I like to stock up on any items needed to get my fermentation off to a healthy start. You don't want to be looking at a bin of crushed grapes only to realize that you don't have everything needed to dial it in. Here are some helpful items that I like to make sure I am stocked up on before crush day, so that I am not caught with my grapes down!
While you can do a wild fermentation, I find it far too risky for my taste and prefer to keep a few reliable yeast strains on hand. Most commercial yeast offerings are just reliable yeast strains that have been isolated from the wild and cultivated for your use. One of my preferred red wine yeasts is Lavin ICV-D21, which was isolated from Languedoc, France. D21 has relatively low nutrient needs and will ferment dry with very few issues. Another good general-purpose yeast for just about anything is EC-1118. You will find that just about every wine kit uses this yeast. EC-1118 is technically a champagne yeast but is capable of fermenting happily in a wide range of environments. If you want to intentionally stall the fermentation to leave some residual sugar, you may want to opt for a low H2S producing yeast like Lalvin Sensy or Renaissance Fresco. These are less likely to create off odors and flavors when dropping the temperature to the point of stalling.
2. Yeast Nutrient
A balanced nutrient blend is essential for providing the needed nitrogen, amino acids, and micronutrients to your yeast population. Fermaid K is a great balanced nutrient and is the backbone of my feeding regimen. I like to keep a little Diammonium Phosphate (DAP) on hand, which helps to bring back a fermentation that is showing signs of stress or accommodate a yeast with high nitrogen needs. A stressed fermentation can produce excess stinky hydrogen sulfide, or acetic acid. Growers will sometimes provide Yeast Assimilable Nitrogen (YAN) values, which can give you an idea of how much nutrient you may need to add. Ideally, you want to feed the yeast just enough to get through the fermentation smoothly. Nutrient availability during aging can be used by bad bacteria like acetobacter, so be sure to wean off the nutrient after about 1/3 to 1/2 sugar depletion.
3. Tartaric Acid
This is the preferred acid for adjusting a grape based wine before fermentation. Acid blends contain tartaric, malic and citric acid. Too much malic acid in a wine can cause a sour apple taste, or result in an overly buttery wine if malolactic fermentation occurs. Citric acid can be converted to acetic acid by both yeast and malolactic bacteria. All three of these acids are naturally occuring in grapes, but tartaric acid is the dominant grape acid and generally the go-to choice for acid adjustments.
4. Potassium Bicarbonate
If you run into an overly acidic batch of grapes, you may need to bring the acid down a bit. Potassium bicarbonate combines with tartaric acid to form cream of tartar (potassium bitartrate) crystals which will precipitate out of the wine, and raise the pH while lowering the titratable acidity. I like to keep a little potassium bicarbonate on hand just in case. As a bonus, potassium bicarbonate can be used in the vineyard or garden to help control powdery and downy mildew.
5. Potassium Metabisulfite:
This is your primary defense against unwanted microbial activity and oxidation. Because potassium metabisulfite happily reacts with oxygen, it will slowly lose effectiveness over time and contribute less SO2 to the wine with the same addition. I like to get a fresh batch of potassium metabisulfite each season, and use the old stuff to make a homemade sanitizing solution.
6. Tannin Powder
Reactive tannins help to build mouth feel, lock in color molecules, and reduce green, herbaceous characteristics in red wines. I like to use FT Rouge from Scott Laboratories during primary fermentation on most of my red wines. Powdered tannin are generally a lot less harsh than the naturally occuring tannin in grape seeds, skins and oak.
7. Malolactic Bacteria
MLF or malolactic fermentation will often occur without needing a bacteria addition, but a safer bet is to innoculate with a malolactic culture of your choice. These are offered in freeze dried and liquid formats and should be used quickly after opening. When selecting a malolactic bacteria for your wine, be sure that it offers enough alcohol tolerance and acid tolerance for the specific must. I generally use CH16 from Christian Hanson for my red wines, which assures swift and reliable fermentations. A stressed malolactic fermentation will create a more buttery wine by releasing more diacetyl. As a winemaker, you can control this to some extent through bacteria choice, wine temperature and nutrient availability.
These help to break down grapes and grape particles and substantially improve extraction. Additionally, enzymes can help to prevent a stubborn pectin haze from clouding your otherwise crystal clear wine. Basic pectic enzyme is readily available at most home brewing shops, or you could opt for a more complex and thorough enzyme like Lallzyme EX. Add enzymes several hours before kicking off fermentation or adding any tannin products.
This blend of yeast micronutrients is used during the yeast hydration process to build a colony of robust ninja yeasts. These well nourished and happy yeasts are less likely to cause fermentation problems later on. I have been using GoFerm for the last few seasons with good results.
10. Oak Cubes
This is a good time to stock up on your oak products, whether it be cubes, spirals, chips, or barrels. Oak cubes are a natural source of reactive tannin that can be used during primary fermentation to provide similar benefits to tannin powder. The lighter toast cubes are generally preferred during fermentation, and heavier toast later on during aging. I like to keep a bag of medium toast and heavy toast american oak cubes on hand.
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If you have any other items that you like to stock up on before the wine harvest, please post in the comments!