Frequently Asked Questions – Fermentation/Cellar
Yeast
Q: How much yeast should I use to ferment wine?
For standard primary fermentation inoculation, we recommend an addition rate of 2 lb/1000 gal (25 g/hL) of total juice to achieve a stable and effective population. For high Brix (greater than 25 °B) juices, increase the inoculation rate to 2.8 lb/1000 gal (35 g/hL). To restart a stuck/sluggish fermentation, refer to Scott Labs Recommended Method to Restart Stuck Fermentations.
Q: How do I rehydrate my yeast?
Q: How do I restart a stuck fermentation?
To restart a stuck/sluggish fermentation, please refer to the following PDFs:
Q: What yeast should I use for a particular wine?
Select yeast based on the grape and style of wine you would like to create. You should also consider your fermentation conditions (e.g. temperature, high BRIX, etc.) and must nutrient levels (YANC). Select the best strain that can tolerate and thrive in your must/juice condition and still deliver the sensory characteristics you desire. For more information about our available strains, please refer to our yeast products page. Please refer to our Varietal Reference Chart (PDF) for suggested yeast strain by varietal type.
Q: What is the best yeast to use for cider or fruit wines?
The top yeast strains for fruit wine fermentation are ICV-K1 (V1116), EC1118, DV10, 71B, Actiflore C, VL1, R2, and W15. For cider fermentation, DV10 is a top choice, followed by ICV-K1 (V1116) and EC1118.
Q: Is it okay to ferment two yeast strains together in the same tank?
Introducing two strains into a must will create a competitive situation wherein each yeast strain will attempt to dominate. This can lead to reduced populations, off flavors and aromas and a greater chance of a stuck or sluggish fermentation. To optimize yeast strain sensory components, ferment each strain separately and then blend after alcoholic fermentation.
Q: I have high levels of malic acid in my juice. What yeast strain can I use to help lower the acid level?
Some yeast strains are able to metabolize malic acid at greater rates then others. VRB, 71B and AC- are yeast strains that have been observed to reduce malic levels.
Q: What is a yeast killer factor?
Killer yeast contain a toxin in their cell wall structure that allows them to kill toxin sensitive foreign yeast cells. Most killer strains of S. cerevisiae have good fermentation kinetics and, therefore, have a greater chance of dominating the fermentation. If indigenous yeast is perceived as a potential problem, strains with this factor may be beneficial. Our various yeast strains can exhibit, be sensitive to or have a neutral reaction to this factor.
Q: What is the temperature range of yeast?
Each yeast strain has a temperature range in which it is most active or most sensitive. For specific yeast temperature requirements, please refer to our Yeast Reference Chart. (PDF)
Q: I have a stuck fermentation and the fructose fraction is higher than the glucose. Which yeast should I use to restart my fermentation?
A good yeast selection for a wine with a high fructose fraction is ICV-KI (V1116). ICV-K1 is fructophilic and a vigorous fermenter. This strain exhibits a killer factor that is helpful when indigenous yeast are still present.
Q: My first attempt to restart a stuck fermentation failed. Should I try again with the same yeast strain?
The first yeast strain used may not have acclimated to a difficult condition of the wine or was inoculated with a low population. It is often better to chose a strain better adapted for high alcohol, high SO2, or a competitive atmosphere. Using the same strain may work the second time, but it may not. Make sure to carefully follow a recommended restart protocol.
Q: Can I open and partially use an active-dried yeast culture and reuse the balance at a later date?
A dried yeast culture will begin to absorb moisture as soon as it is opened. This can trigger the yeast to reactivate. If no must or nutrients are available the yeast die or become weakened. An open container also becomes a rich media for possible microbiological growth. It is recommended to close a container tightly immediately after opening. The balance should be used within a short period of time (1-2 weeks).
Q: How should I store my yeast?
Store yeast in a cool, dry environment.
Q: To enhance wine complexity, should I put different yeast strains in the same tank, at the same time?
This is not recommended. The introduction of two yeast strains into the same tank creates a competitive atmosphere. Like Ali and Frazier, these strains will duke it out competing for nutrients and sugars. Competition leads to weaker yeast populations and an increased chance of stuck or sluggish fermentations. Also, yeast strains that display a competitive factor will knock out sensitive strains so fast, you will think the fight was promoted by Don King.
So how can you do a dual fermentation? Fill two tanks with the same juice/must. Then inoculate each tank with a different yeast strain. Blend the tanks after alcoholic fermentation to achieve your goal of complexity without putting your fermentation's success at risk.
Encapsulated Yeast
Q: How should I store my encapsulated yeast?
Store at 4°C (refrigerator). Do not freeze.
Q: What is the shelf life of encapsulated yeast?
At optimal conditions, one year for ProRestart DV10 and six months for ProDessert BA11.
Q: What should I do if my mesh bag rips and the beads escape?
Put remaining beads in an intact bag. If loss of beads is extreme, turn over tank twice a day to circulate beads and filter after fermentation as you would in a standard fermentation.
Q: What are the tolerances of ProRestart DV10?
A maximum final alcohol tolerance of 15.5 % alcohol and a free SO2 < 15 mg/L. Previous additions of yeast hulls (25-30 g/hL) may considerably improve their efficiency of ProRestart DV10 due to the absorption of toxins.
Q: Can I reuse ProRestart DV10?
Yes. ProRestart DV10 can be used twice if desired. Be careful to only reuse when no question of cross-contamination exists. Request procedure for sugar solution storage for short periods between use.
Q: Can I reuse ProDessert BA11?
No. ProDessert BA11 should be used only once.
Q: What if my wine is stuck and only contains fructose. Should I use ProRestart DV10 or a traditional restart method?
ProRestart DV10 has been proven to work in high fructose environments. However, more fructophilic (fructose loving) standard yeast strains, such as ICV-K1 (V1116), may be preferred.
Q: Will the alginate encapsulation hurt my wine in any way?
The alginate should not impart any characteristic to the wine.
Q: Should I use ProDessert BA11 to conduct a secondary fermentation in the bottle?
No. ProDessert BA11 is not designed to withstand the more difficult conditions of a secondary fermentation. ProElif DV10 was developed for that purpose.
Q: How do I suspend my tank bags?
Tank bags should be filled with no more than 5 kg of encapsulated yeast. Tie bags to strings attached to the top of the tank and anchor the bag with a weight or ballast to prevent the bag from floating.
Q: How should I fill my barrel bags?
The recommended dosage per barrel bag is 170 g ProRestart DV10 and 227 g ProDessert BA11. Place the filled and rehydrated bags through the barrel bung hole and attach to the top of the barrel. The use of a ballast is not necessary.
PreRestart DV10 Tech Sheet (pdf)
Malolactic Bacteria
Q: What is the difference between MBR and standard cultures?
MBR: Microbe-Be-Ready cultures can be directly added to wine after being rehydrated. Standard cultures must go through a build-up protocol prior to inoculation of the wine. The standard build-up process can take from 5 to 20 days to prepare.
Q: How do I build up a standard culture?
Q: How do I start a MBR culture?
Rehydrate in chlorine-free, 21-25° C (70-77°F) water for 15 minutes. Add the mixture directly to wine.
Q: When should I inoculate with ML?
ML should be inoculated at the end of primary fermentation. This helps avoid competition with the yeast that can lead to stuck fermentations. Bacteria can also produce large quantities of volatile acidity (VA) while fermentable sugars are present.
Q: What are favorable or harsh conditions for ML?
An optimum environment for malolactic bacteria includes a temperature between 20-25°C (68-77°F), alcohol below 13% (v/v), total SO2 below 25 ppm, pH above 3.4, little or no oxygen, low levels of short and medium chained fatty acids, low levels of organic acids and low levels of polyphenols.
Q: Should I use nutrients?
If your wine is bordering the optimal limits for the bacteria environment, nutrients may be desired. Nutrients like MaloStart can be used to help ready the wine for inoculation by reducing toxic influences on the bacteria and promoting growth. Other nutrients like Opt'Malo Plus can be useful to create an environment that promotes clean and quick MLF.
Q: Should I inoculate if my VA is creeping?
If your VA is creeping, you may already have lactic acid bacteria (LAB) present in your wine. Before inoculating first control the VA problem by assessing contamination and treating with filtration, SO2 or whatever is appropriate for the situation.
Q: Do all ML strains produce diacetyl?
In the world of ML, some strains produce more diacetyl than others. Diacetyl is the compound responsible for the "buttery" character found in white wine. Standard OSU is well known for its diacetyl production.
Q: What ML strain should I use for a particular wine?
ML strains should be selected based upon desired
sensory effects and specific wine fermentation conditions. For
a description of our ML strains, please refer to our Malolactic
Bacteria Culture Page.
Q: How can I tell if my ML culture is healthy?
Air traps can be used to see if metabolism is occurring in the wine. Also paper chromatography can normally be used to monitor the production and reduction of lactic and malic acids. Another method is to listen for the small bubble "spritzing" usually found in these fermentations.
Q: How can I prevent, stop or allow for a partial ML fermentation?
Traditionally SO2 has been used to control the rate and occurrence of MLF, however lysozyme can be used effectively to control the aspects of MLF and reduce the total amount of SO2 needed. Ultimately, sterile filtration is the best way to ensure complete removal of malolactic bacteria.
Q: Can I open and partially use an MBR culture and reuse the balance at a later date?
A bacteria culture will retain some of its viability even after being opened. Once opened, however, the bacteria media will become susceptible to contamination. Exposure to moisture in the air can encourage the bacteria to start growing in the package, thus reducing viability significantly. If you do decide to save your leftover bacteria, store in a dry, sealed container below 0°C and used within a short period of time (1-2 weeks).
Q: How should my cultures be stored?
For short periods of time, bacteria can be stored in the refrigerator at 40°F, however for longer viability store in a freezer below 32°F. Be sure to let the bacteria sit at room temperature before beginning rehydration.
Q: What is the shelf life of ML cultures?
Cultures are marked with production dates and expected viability under different temperatures. (12 months at 40°F and 18 months at 0°F).
Q: What is that "buttery" character?
Diacetyl is the chemical responsible for the buttery character found in white wines that undergo MLF. Diacetyl is formed as a by-product of the catabolism of pyruvate, which is often derived after MLF from citric acid sources. Citrate and oxygen concentration will increase diacetyl levels while living yeast cells and SO2 levels in the wine will reduce concentrations. The ML strain used will also have an effect based on its catabolism of citric acid. Thus, there are multiple factors to think about when addressing the "butter issue". The initial state of the wine, winemaking method (for example sur lies) and choice of bacteria strain all must be considered. For example, OSU is a strong diacetyl producer while MBR 31 produces low amounts of diacetyl.
Nutrients
Q: What is YANC?
YANC stands for Yeast Assimilable Nitrogen Content. It is the sum of assimilable nitrogen from ammonium ions and the assimilable Free Amino Nitrogen (FAN) present in the juice/must. Low levels of YANC are associated with the production of undesirable sulfide compounds. Recommended levels range from 250 ppm-350 ppm or higher depending on the initial BRIX level.
Q: Are Fermaid K and Superfood the same?
No. While both are yeast nutrients, each is a proprietary blend from two different manufactures. While similar in nutrient content, Fermaid K can be added at smaller rates to achieve the same effect as Superfood. In fact, the recommended dose of Superfood is twice that of Fermaid K!
Q: Why should I use GoFerm?
GoFerm immediately gives your desired yeast a leg up over other organisms during fermentation. GoFerm is added to the rehydration water of the selected active dried yeast. A "sponge effect" allows the yeast to soak up the nutrients as they soak up the water. Micronutrients are more bioavailable to the yeast, which encourages a strong and smooth fermentation.
Q: When should I add GoFerm? How much should I use?
Go-Ferm should be added in the rehydration water of the active dried yeast prior to the yeast addition itself. The recommended dose is to add 2.5 lb Goferm/1000 gal (of total juice/wine) into 20 times its weight of clean 43°C(110°F) water. Stir the GoFerm to dissolve. For optimal performance, maintain a ratio of 1 part yeast to 1.25 part GoFerm.
Q: When should I add Fermaid K? How much should I use?
Fermaid K is best added at 1/3 of sugar depletion at a rate of 2 lb/1000 gal. Fermaid K should be hydrated before adding to an active fermentation to avoid CO2 release and overflowing of tanks or barrels.
Q: Should I use Diammonium phosphate (DAP)? When should I add it?
DAP should be used when YANC in below 125 mg N/L. Fermaid K contains some DAP, but for very low Nitrogen content must, DAP is recommended to bring YANC to above 150 mg N/L. Each 2 lb/1000 gal (25 g/hL) addition yields 50 mg N/L inorganic (ammonium) nitrogen.
Q: How should I add Dynastart when restarting a stuck fermentation?
The recommended addition of Dynastart is 2.5 lb Dynastart/1000 gal (of stuck wine) into 10 times its weight of clean 43°C(110°F) water. Stir solution gently. When the solution has cooled to 40°C (104°F) add your yeast and begin your standard rehydration protocol for that yeast.
Q: How do I test for nitrogen levels in my juice/must?
Levels can be tested through formol titration or the NOPA method. Inorganic nitrogen can be determined by using an ammonia probe.
Q: I have an organic wine program. Which yeast nutrients can I use?
Some nutrients do not conform to organic qualifications while others are tailored for this purpose. For organic wine, we suggest Bioactiv or Fermaid 2133.
Q: What is the difference between Fermaid K and Fermaid 2133?
Fermaid 2133 is a whole yeast cell powder providing
amino nitrogen and B vitamins. Fermaid K is a blended complex
yeast nutrient containing Magnesium Sulfate, Inactive Yeast, Thiamine,
Folic Acid, Niacin, Biotin, Calcium Pantothenate and DAP.
Q: When should I use yeast hulls?
Use yeast hulls to fine out toxins in the case of sluggish/stuck fermentation, to increase the surface area of clarified juice, and to supplement survival factors such as sterols.
Q: Which nutrients are considered Kosher?
The only nutrient that conforms and is documented as Kosher is Fermaid K (Kosher).
Q: What is Granucel? How should I use it?
Granucel is composed of cellulose powder. It is used on highly clarified juice to help keep yeast in suspension.
Q: When should I use Bioactiv and how much should I use?
Bioactiv is an excellent nutrient source when inorganic nitrogen (ammonia) is not desired. It can also be added to a sluggish fermentation to boost fermentation performance. It is added at a rate of 2.5-5.6 lb/1000 gal.
Q: How much nutritional value does Opti-Red add to the juice/must?
Opti-Red is basically a highly specific form of autolyzed yeast. There is some benefit derived from this organic nitrogen source, but the use of Opti-Red should not preclude the use of other nutrients like Fermaid K, GoFerm, Bioactiv or Dynastart.
Q: What is the source of nitrogen in Fermaid K, GoFerm, DAP and Bioactiv?
The nitrogen source of the listed nutrients is as follows:
- DAP=100% ammonium ions
- Fermaid K = ammonium ions + Free Amino Nitrogen (FAN)
- GoFerm and Bioactiv = 100% Free Amino Nitrogen
Q: Why are pantothenate and magnesium sulfate important to yeast cells?
Pantothenate helps to keep open important metabolic pathways that dramatically reduce the production of H2S. Magnesium improves yeast alcohol tolerance.
Q: Do different yeast strains require more nutrients than others do? Why?
Yes. Each strain has distinct fermentation kinetics. One strain may require less of one nutrient compared to another strain. Do your research. See our Yeast Quick Reference Chart (PDF) to help determine your yeasts' specific needs.
Q: Is nutrient addition timing important? Why?
Yes. Yeast metabolize nutrients at different times throughout fermentation. Dosing nutrients at the most optimal moments can enhance yeast performance. As fermentation progresses and the ethanol level rises, yeast becomes less and less able to assimilate nutrients. For this reason, each nutrient has been created for specific addition times. For example, GoFerm has been designed to add during rehydration. Other nutrients like Fermaid K are added at one-third sugar depletion and never into the rehydration water.
Fining Agents
Q: What is the difference between Argilact and Polylact?
Argilact is a combination of bentonite and casein whereas Polylact is a blend of PVPP and casein.
Q: My wine is astringent. What fining agent should I use to reduce the astringency?
Gecoll Supra, a liquid gelatin, is a good choice for the reduction of astringency. This gelatin was specifically developed to target harsh tannins and phenolics. Another way to reduce astringency is to add polymerized tannin like TanCor Grand Cru or Tanin Plus. Bench trials are highly recommended prior to use.
Q: What is Sparkolloid?
Sparkolloid is a proprietary blend of polysaccharides and DE. Sparkolloid exhibits a strong positive charge that neutralizes and complexes with clouding particles. Developed in house, Cold Mix for Juice and Hot Mix for Wine are powerful fining agents available at a minimal cost.
Q: Can I combine Argilact and bentonite?
To achieve optimal results, it is best to use Argilact first and if still needed, follow with bentonite. Bench trials are highly recommended to determine proper dosing levels.
Q: What is Ichtyocolle? When should I use it?
Ichtyocolle is Isinglass treatment developed especially for applications with white and rosé wines. Made from the bladders of fish, this fining agent is proven to enhance clarity and brilliance even in wines made from botrytised grapes.
Q: What is the difference between Gecoll Supra and Gelarom?
Gecoll Supra is best used to fine out astringent polyphenols in wine, where Gelarom is better used to enhance the fruit quality of a wine. Because of each gelatins specific attributes, Gecoll Supra is often recommended for red wine pressings and Gelarom is recommended for lighter style rosé or white wines.
Q: I detect bitterness in the finish of my wine. What can I use to remove it?
Often, Argilact is a fast and easy way to reduce bitterness. If you have already protein stabilized with bentonite, try adding a small amount (25 ppm) of the tannin Galalcool SP to eliminate the bitterness. The Argilact will precipitate the bitter molecules while the tannin will mask it. Bench trials are recommended.
Q: What is the shelf life of the liquid gelatins?
If stored refrigerated in an airtight container, liquid gelatins should last 2 years.
Q: How should I store Gecoll Supra and Gelarom?
Liquid gelatins should be stored above 5°C(41°F) and not subjected to extreme temperatures.
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