Pitching yeast

Some thoughts:

- Did you add sodium metabisulfite to kill off native yeasts prior the pitching the yeast? If so, how much and when? High free sulfur in the must will inhibit yeast growth.

- At the time of pitching, having the yeast near the same temperature as the must minimizes thermal shock (which can kill a lot of the yeast population).

-Did you add any DAP (Diammonium Phosphate) or balanced yeast food (Fermaid K) to the must prior to pitching the yeast? (they provide a favorable environment for the yeast to grow)

- Year-old yeast may or may not still be viable. Before you pitched your yeast, did u check for yeast viability? (i.e take a little bit and put it in in warm water(around 100 deg F) with a dash of yeast nutrient and checking for the FIZZ?

- your must may be too cold for the yeast to be active yet. What temperature is it now?

Good luck. Gene

Gene, Thanks and here are the answers (or most of them) I added 1 tsp K-metabisulfite to the grapes at crush

The juice was cool and the yeast mixture was warmer at the time I threw it in. Could be a problem.

I added superfood (1 tbsp) with the yeast.

I will test the yeast viability tonight.

Not sure what the temp is right now, but I would say it is probably somewhere around 55-60 degrees. (Total guess).

Thanks, Joe

1 tsp 'fresh' K-metabisulfite per 4 gallons must yields on the order of 65-75ppm free SO2. The pH of the must affects the consumption of the free SO2. 20ppm free SO2 at crush is enough if your must pH is down around 3.2-3.4. If your pH is above 3.6, then I'm guessing you'll be needing at least 40-50 ppm free SO2 addition at crush. (NOTE: The K-metabisulfite slowly degrades over time in the presence of moisture into potassium sulfate, which does not release free SO2. So if your K - metabisulfite is also a year or more old, you have less free SO2 than u calculated.) I hope you didn't add the K-metabisulfite just before pitching the yeast. Typical practice is to add K-metabisulfite 1-3 days before pitching the yeast (i.e. one to three day cold soak). I'm guessing I have about 10-15 ppm free SO2 remaining at the time that I pitch yeast in my sauv blanc.

Adding warm yeast mix to cold must isn't 'ideal practice', but you can usually get away with it if your yeast is active and healthy. The fermentation is fairly forgiving... as long as you don't kill too much of the yeast in the addition process. I allow my 100-110F temperature yeast mixture to cool (on its own - not by refrigeration) to around 70-80F before adding to about 55-60F must. I don't stir the yeast into the must (makes for quicker start of fermenation... so that you're not diluting the initial yeast throughout the must). I just pour my yeast mixture into the must and cover, letting the bubbling from fermentation and the heat gradients in the fermenter do the mixing to achieve a 'homogenous' fermentation after a few days.

For Sauv Blanc, I let the must temperature rise naturally to about 70F (until I hear active fermentation), then start lowering to 55-60F, holding it there until fermentation stops. My fermenter is a 4 gallon stainless steel pot (with inverted lid) in an oversized ice chest. I add frozen one-pint bottles of water to the ice chest (not into the fermenation tank) to do my slow cooling. I start with 5-8 'ice' bottles and change them out once or twice a day, depending on how fast the ice is melting and what temperature the must is at. My rule of thumb is no more than 1F per hour temperature change, and no more than 10F cumulative change per day. That minimizes the thermal shock to the yeast.

Others have their favorite procedures... would be interested in hearing what works for others.

Regards, Gene

Joe - I think you added a lot more SO2 than you thought....around 220 ppm. The K Metabisulfite I buy from Presque Isle weighs 5.8 grams per teaspoonful. K Metabisulfite is 57.63% SO2 so a tsp contains 3.34 grams SO2. Divide the 3.34 grams SO2 by 4 gallons and you end up with about 220 ppm SO2. This may be your problem with a slow fermentation.

Bill Frazier Olathe, Kansas USA

William and Gene, Thanks so much for the info. Good tips. I checked it when I got home last night and the fermentation had started. Phew! I will be employing your guys's tips next time though. Thanks!

Joe

Joe, Bill is right about the SO2, although Gene is right about pH dependency. I just think Bill is closer to the SO2 load you put in than Gene is. The normal dose for a 5-gallon carboy is 1/4 teaspoon of K-meta, and you quadrupled that for only 4 gallons.

My advice has always been to make a yeast starter. You will know very quickly if the yeast is viable because the yeast is confined to a small volume of liquid. If you dump it into a 4 or 5 gallon volume, you might waste two or three days before deciding the yeast is no good.

Generally, when making a starter, never put yeast in water warmer than

100 degrees F. Most wine yeast die at 104 degrees, although some can hold out to 110. Don't play with the health of your yeast. They make the wine. You just facilitate the experience and clean up after them. But each yeast strain is different.

You said you were using Lalvin ICV-D254. This yeast has an optimum fermentation range of 64-82 degrees F., with a low tolerance of 53 and a high of 89. Within those limits, it should ferment. In the optimum range, it should ferment very well. However, it is a low-foaming slow fermenter, which is why it delivers a rich mouthfeel.

As for temperature shock, I am fairly certain the yeast do not experience die-off unless they exceed the limits for the strain (for this one, as described above). Yeast that have undergone temperature shock are usually just stunned and go into a sort of hibernation that can last from several hours to several days. ICV-D254 is an ADY (active dry yeast), not a freeze-dried yeast as many people think. It becomes active when rehydrated. I don't think it can go into shock until then (I refrigerate mine at 40 degrees F.), so if you added the dry yeast to a cold must it should have activated if within the temperature limits mentioned above.

I hope this helps. If I misstated anything, Lum, Tom S., Ray, Ed, Joe, and others will correct me so stay tuned.

Jack Keller, The Winemaking Home Page

Thanks for the correction, Jack. Sounds like I had faulty info on powdered K-metabisulfite (I use Campden tablets myself due to very small lot size). Thanks also for the comment on yeast starter temperature. My yeast must have been pretty healthy to activate and survive above 100F.

Gene

Actually, 104 degress F is the recommended temp from one of the yeast companies.

Again accourding to a yeast company, you can lose as much as half the viable cells from temp. shock. The recommendation was to add a small amount of must to the yeast starter 15 minutes after rehydrating the yeast in plain water. Continue to add small amounts of must every 15 minutes or so until the starter is at the temp. of the must, then pitch.

Andy

Note that different yeast companies have different suggestions on how to introduce thier yeast to your must. One will recommend that you sprinkle it over the top and not stir it in. Another will recomend that you add the yeast to a certain type of starter. Another will tellyou to rehydrade and then add to a starter. I assume that each company knows the best way you should handle their yeast according to the way they handle the yeast themselves in preparation. I recommend that you do it the way the company that makes the yeast suggests.

Ray