Different yeast rehydration procedures
You may have noticed on wine yeast packets and in the literature that there are mainly two different ways to rehydrate active dried wine yeast. The one procedure is a water only procedure and the other a water juice mixture. The existence of two different procedures on different companies’ yeasts can be quite confusing to winemakers if they would like to standardize their cellar practices. Well the good news is you can. Just pick one that suits you best. The reason why one company – say Lallemand – has the water only rehydration and another company – say Anchor Yeast – has a water/juice rehydration is simply legacy. In the seventies when both companies started to produce and sell wine yeast they just happen to choose different methods and then stuck to it. What is very important is that you follow the method you choose exactly and not take short cuts. Yeast rehydration is extremely important for optimal yeast functionality.
So you might ask why two methods exist in the first place. Well, the best way for me to explain this is that water is what was taken out of the yeast when dried after production, so water is all that’s needed to restore the original cell form. However, water has no osmotic strength, which means that if you do not follow the exact protocol and add juice to the rehydration mixture after 30 minutes, then cell constituents (very small, but very important stuff on the inside of the yeast) can leak out from the high (inside the yeast) to the low (water) osmotic pressure. Simple chemistry. The yeast will lose some or all of its functionality, which could result in fermentation problems. So by adding one third juice to your rehydration mix you add some osmotic pressure – making rehydration more idiot proof. You also provide something for the yeast to start fermenting on right away.
In big co-operative wineries the yeasts for several tanks are rehydrated at the same time. So by the time the winemaker returns to the first tank’s mix – 30 minutes could have passed. In this case the water/juice rehydration would be the safer option.
I don’t have any evidence that one method is more effective that the other if both are followed exactly as prescribed. If anyone out there has experience of one being better than the other then please let me know.
This was a rather boring blog to write. Will have to bring in more humor and opinion in my next attempt. Its useful information though…
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August 8th, 2010 at 12:05 pm
Hello! I always gave water and juice to rehydrate. My Lab told me last year only to use pure water at the first step. I did so and saw actually no difference . However – 25 years ago when I was working first time in the cellar , we took a bucket and filled it with warm water and juice ( temp. messured by hand), than added yeast and stired it by hand and when it started to foam we filled it directly into the tank. The fermentation was without cooling( 28-30 celcius!) and no DAP , Enzyms etc. Oh my god …. 90 % fermented dry , the rest…. I cannot imagine to produce wine like this today! We used yeast like a tool , not like a partner in winemaking.
Today – the juice management is done at state of the art. Everything is temp. controlled. To rehydrate I take hot water and desolve 20gr/hl Goferm in it. Than we add cold water to 40-38 celcius messured by a laser temp. controll. We add minimum 25gr/hl yeast and let it sink down or stir – it depends on the yeast. After that we inserd an air suply and give air ( normal breath air ) bubbles over the whole time of rehydration. Normal round 1-1.5 hours. After 15-20min we start to cool down with must in steps of 5-7 celcius down. Every 15-20 min we repeat until we are max 5 celcius over tank temp. Than we add to tank and stir. After 36-48 hours after innoculation we give 30-50 gr DAP and another two steps , but never over 10 vol alc. 99,99% of our fermentations are finished dry after 10-12 days. At the stage of 3-1 gr. of residual sugar we add betaglucanase to have more mouthfeel and fine elegance from a yeast , which felt well during fermentation and still can give positiv things even after fermentation. After we implemented a clear procedure for rehydrating and innocultation in our cellar , we have no H2S problems any more.
Especially to give air during rehydration is a very good thing!
Greetings out of the sunny vineyards in the Rhine Valley , Christoph
September 29th, 2010 at 3:47 pm
Thanks for sharing your experience, I’m a young winemaker, I’ve worked in different cellars (with and without juice addition at the beginning) and I’ve always been curious to know what’s the best way, I think the advice of the company who makes the yeast and the experience is the best (now if you use native yeast… definitely the experience!)