Have a question you need answered? Look over this list of questions sent in by other winemakers . If you still don't find what you are looking for, please enter your question below and we will respond shortly!

• When to add Opti-Red or Booster Rouge
• Strong fermentation finish in barrel fermented whites
• Adding too many nutrients
• High fermentation temperature in reds
• Correct timing of ML inoculation
• Re-pitching yeast
• Yeast for ester production in reds
• Fermenting with 2 strains at once

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Does Opti Red have any nutritional value or contain any accessible nitrogen?

Yes, Opti Red is composed of specific inactivated wine yeast fractions, so the natural amino acids found in yeast are present. The contribution is nominal at the equivalent of 4mg/L N for each 12.5g/hL (1 lb/1000gal) used.

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When to add Opti-Red or Booster Rouge

I am VERY interested in your Opti-Red and Booster Rouge products but I would like to know when is the best time to add them: pre, mid or post alcoholic fermentation?

The absolute best time to add Opti-Red or Booster Rouge is in the must.

Opti-Red and Booster Rouge have a high natural content of reactive yeast polysaccharides. These polysaccharides will complex with anthocyanins and tannins as soon as they are released from the skin and result in a wine with fuller structure and enhanced mouthfeel.

If you wait to make the Opti-Red or Booster Rouge addition until mid-fermentation, there are fewer polyphenols available to complex with the polysaccharides in Opti-Red or Booster Rouge.
Opti-Red and Booster Rouge additions, even in a finished wine, will still make a positive contribution but the effect will not be as dramatic.

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Strong fermentation finish in barrel fermented whites

Last year I used BM45 to make barrel fermented Chardonnay with a very high starting sugar. I liked the mouthfeel and aromatic contribution of the yeast but I got a little nervous waiting for it to go completely go dry. Is there anything I can do to keep the fermentation from petering out?

Instead of throwing in the towel on BM45, use Go-Ferm in the rehydration step. Go-Ferm is a specially formulated inactive yeast preparation that has been jacked up with key micronutrients that help yeast survive. Research in high alcohol fermentations show that using Go-Ferm creates healthier yeasts that are able to survive the hostile environment and give a stronger fermentation finish. In addition, you can add another strong yeast like the Uvaferm 43 when the fermentation slows down to help finish the fermentation. You'll still keep the positive sensory influence from the BM45 while helping the fermentation to finish. It's helpful to pre-adapt the finishing yeast to a small diluted portion of the sluggish fermenting must before adding it to the main fermenter.

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Adding too many nutrients

Is there any downside to using nutrients even though they may not be needed? And how does one deal with the effects of too little or too much nitrogen?

If you're using GoFerm and Fermaid K nutrients along with a selected yeast at their recommended addition levels along with the correct timing of addition there is no downside. High DAP additions, above 50g/hL, on their own can have a negative sensory impact. Harsh and bitter sensory properties are enhanced when the juice or must is deficient in micronutrients such as pantothenic acid.

Too little juice nitrogen will "starve" the yeast during the fermentation. The result is usually poor yeast cell growth leading to stuck and sluggish fermentations as well as negative sensory impact. The drawbacks of too much juice nitrogen is controversial. One side is that the yeast will use most of the nitrogen during the fermentation and the other view is that enough will be left over and potentially used by spoilage organisms. Both sides may have valid points.

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High fermentation temperature in reds

In order to extract the maximum amount of tannins and polyphenols in red fermentations, we target a peak temperature of 28–30°C (82–86°F). What are the implications of high fermentation temperature on yeast, especially under high sugar conditions?

Dominique Delteil of the ICV in Montpellier, France provided the following answer. Dominique is the ‘father’ of many popular yeast including ICV-D254, ICV-D80 and ICV-D21.

There are two key reasons to control the temperature in reds.

1. Speed of yeast population growth and resulting alcohol accumulation

When there is rapid yeast growth, the speed of alcohol production surpasses the rate of alcohol excretion by the cell to the juice. This results in an accumulation of alcohol in the cell. This alters the physiological state of the membrane, even if the alcoholic concentration in the juice is still quite low. This early accumulation of alcohol in the cell will affect and limit the cells’ resistance to stress at the end of fermentation.
In grape juice, the speed of cell multiplication reaches a maximum at 28°C (82°F). To avoid this excessive cellular alcohol accumulation, it is recommended keep the temperature below 25°C (77°F) during the 1st third of the fermentation. Avoiding a quick accumulation of alcohol also allows greater extraction through a more complete diffusion of tannins and hydrophilic polysaccharides that occurs more efficiently at lower levels of alcohol. These are generally the more positive components that contribute to the overall sensorial level in the finished wines.

2. Maximum temperature attained during the fermentation and death

High temperature during fermentation is the only direct factor that kills cells. The maximum temperature that a cell can tolerate depends on the health of the cell, the initial osmotic stress and the stress that occurs in the growth phase.
Different enological yeast have different levels of temperature resistance.
In most Mediterranean musts, the risk of cell death becomes HIGH above 28°C (82°F).

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Correct timing of ML inoculation

Recently I received your Lallemand article "Bacteria and Wine Quality". One point caught my interest; it indicates that ML culture should be added after primary fermentation. I had thought that ML should be added after the ferment had hit peak temperature but was still ongoing. The advantages of addition at that time: (1) get it started and finished sooner; (2) start it before alcohol levels get high since ML bacteria do not high alcohol; (3) the heat from alcoholic fermentation helps support ML bacteria growth; and (4) the ML bacteria can take advantage of the nutrients before the yeast use them up.
Could you please comment if my thinking is incorrect, and if so, why is post ferment addition correct?

Thanks for your inquiry and we're very happy to see someone actually reads these booklets!
The topic of the timing of ML inoculation is controversial and experts differ on what to recommend. Many winemaking regions, especially old world regions like France, generally recommend to add the ML culture only after the primary alcohol fermentation has finished. This recommendation is soundly based on experience that has led to occasional problems with high acetic acid (VA) production and stuck primary fermentations. Part of the problem is that ML bacteria, having finished with the malic and citric acids, look for another food source such as glucose. They then can convert this glucose to VA.
The controversy comes from new world winemaking experience, where more winemakers practice simultaneous primary and malolactic fermentations. It all boils down to a risk management decision. Many winemakers are willing to accept potential VA problems in hopes that by performing simultaneous ferments, they will have better success getting the ML to complete before the alcohol content or cellar temperature make it extremely difficult to manage the ML fermentation.

As more information about yeast/ML interactions and ways to better control fermentations becomes available, winemakers will have more confidence to decide the best timing for ML culture inoculation. Recent studies have shown that the risks involved with simultaneous ferments can be minimized when the primary fermentation is well managed. This includes using the right nutrients and adding them at the right time, making sure that the pH is below 3.5, and using the ‘right’ combination of yeast and ML bacteria.
Cheers!
Gordon

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Re-pitching yeast

I want to re-pitch yeast in a red fermentation. The scale is very large - 160 tons per fermenter. What are some key factors / risks to look for?

Repitching is always a matter of risk.

How contaminated is it from the first fermentation? If the first inoculum was in pasteurized juice in a sterile fermenter with well sanitized pumps and lines, there would be very little risk in repitching.

If the first inoculum was into must from very clean grapes that had been harvested in sanitized containers into sanitized presses into sanitized pumps, lines and fermenter tanks, one repitching would be of reasonably low risk.

Repitching late in the harvest is much more risky than repitching the first few days of the harvest. Sanitation usually goes down hill as the harvest progresses. If you have very good connections with the powers to be up in heaven or you are always a big winner in Las Vegas you might press your luck and repitching one time from one of these fermentations.

Using a fresh inoculum for each fermentation is a cheap insurance policy.

Cheers,
Clayton Cone

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Yeast for ester production in reds

What is a good yeast strain to use for red wine grapes (especially Zinfandel) grown in California's hot central valley? I was thinking of using ICV GRE for minimizing sulfur/vegetal flavors, but I heard it has low production of esters, something that is really needed for hot climate grapes.

ICV-GRE is an excellent choice for minimizing sulfur and vegetal characters. If, however, ester production is your primary goal 71B would be the best choice. Its esters seem to be relatively stable when compared with other wine yeasts.

Neither ICV-GRE nor 71B are orientated towards big-structured red wines. They are for more aromatic, easy-to-drink wines. If you are targeting a red wine with underlying structure, consider yeasts such as L2226, BRL97 or ICV-D254, especially if you're going to exceed 14% potential alcohol.

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Fermenting with 2 strains at once

I have two favorite yeast strains and have always fermented them separately and then blended the finished wines. Now that I know what combination I like will I get the same effect by blending the right proportion of yeast together and fermenting the grapes in one tank?

Combining two dried strains and fermenting one tank is nice in theory but we have found you don't always get the same effect as fermenting the strains separately and then blending! Each yeast strain reacts differently in different environments. Competitive factor aside, one of the yeasts might adapt better to the specific environment than the other and dominate the fermentation. Although it takes more space in the winery, we recommend that to get the most out of our yeast ferment each strain separately and then blend to your stylistic goals.

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