Cold Soak before fermentation

[AFW]

Help me understand about Cold Soak. I have some Merlot grapes coming and have read somewhere that prior to fermenting let the crushed grapes sit in a cold bath 60 f for a couple of days ( 2 - 3 ) to extract color and tannins. What’s your thoughts. This will be my first attempt at fresh grapes.

Thanks,
Alan

 

[winemaker81]

The idea behind cold soaking is to improve the aroma and flavor. The AWRI has a description that goes into detail:

https://www.awri.com.au/industry_su...ing-practices/winemaking-treatment-cold-soak/

Note that 60 F is too warm, your grapes will probably start to ferment, even if slowly. AWRI recommends 5-10 C (41-50 F) as most yeast and other micro-organisms will not grow at that temperature.

I typically crush grapes on one day and inoculate the next day. For CA grapes which are shipped cold (I'm in NC), the timeline in between may be longer as they need to come up to temperature (62-65 F), whereas local grapes are already ambient temperature.

 

[AFW]

Thanks Brian for that link. Probably not do it as these Merlot grapes are coming from California and will be a couple of days from harvest. I read the article and sounds that you need to do it to freshly harvested grapes.

 

[winemaker81]

Happy to help.

Your grapes should come in cold, and it may take 2 to 3 days for them to come up to temperature, depending on your circumstances. You're going to get short cold soak anyway.

Our grapes typically arrive on a Friday and are unloaded into our coordinator's air conditioned garage. (we do a group purchase). The following day we divide up the grapes and those that want to, crush on site. The following day (Sunday) is when my grapes are above 62 F, so I inoculate.

 

[BarrelMonkey]

I typically crush grapes on one day and inoculate the next day.

Another good reason to wait a day before inoculating is that grapes often 'soak up' after crushing, meaning that sugar, acids etc start extracting from the fruit and change the characteristics of your starting must (and so potentially affect the decisions you make about your winemaking). Last year I made a Syrah which tested as 23.0 brix, pH 3.23 and TA 6.4g/L at crush. Next day: 24.0 brix, pH 3.38, TA 4.8g/L...

 

[Paulie vino]

This video goes into good detail and is supported by scientific studies

 

[Garagista]

This video goes into good detail and is supported by scientific studies

Great Caesars Ghost! That’s a lot of information to absorb. Thx.

 

[Garagista]

I’m not the sharpest pencil in the box so I need this dumbed down … a lot. These are the nuggets I got from this study. BTW, I am not aware of the peer review status of this study so we need to treat it as one data point. This is for grapes, not kits.

1. Cold soak does not really do anything material to the color and tannin.
2. Extended maceration can actually reduce the color intensity of the wine.
3. The best method to increase both color and tannin is to selectively mix the hard press wine with the free run wine until we reach the level of color and tannin we want.
4. Adding our own tannin gives only modest improvement in tannin.
5. Rack and return (saignee) only gives modest improvement in color and tannin.
6. Enzymes impact tannin but not color.
7. Enzymes don’t have any significant effect on taste except for astringency.
8. Rack and return (saignee) improvements decay over 18 months until there is no benefit
9. Higher temperature fermentation increases color and skin tannin but does not materially increase seed tannin.
10. The selection of yeast strain is actually very important.
11. There is a yeast called Rhone 2323 that appears to be a significantly superior strain.
12. Extended maceration lowers skin tannin and raises seed tannin.
13. Whole bunch fermentation does not change the favor profile except it increases the “green pepper” taste significantly

So, these are my over-simplified interpretations of the study. Your interpretation may vary.

• Skip the cold soak
• Skip the extended maceration
• Skip the rack/return
• Ferment warmer
• Blend the hard pressed wine into the free run wine according to my preferences.
• Continue to use enzymes
• Select the yeast very carefully
• Don’t do whole bunch fermentation

Just my .02.

 

[Jezroti]

I have been doing a cold soak for the last few years. I have had no issues only better quality wine. I have been insulating the fermenter with a moving blanket and tarp. And cover with a lid on top of a breathable cloth lid. Dropping frozen gallon jugs to maintain temps under 50 degrees.

 

[Rotundifolia]

Gaia yeast can be used to improve the odds of less spoiler organisms. This yeast will not create any caps nor any real sign of fermentation, so you will know that things are ok. GAIA only has tolerance to 3% alcohol so it will not compete with the yeast you inoculate for fermentation. It is a good idea to add 5% of the yeast that you want to inoculate when cold soaking so when you warm up you yeast has a head start. I also add a little extra nutrients in the beginning since both GAIA and your yeast will be using nutrients up to 3% alcohol.

I do use a big feeding trough from a tractor/farm store. I put the brute in and fill the trough up with ice. I add frozen gaterade bottles, use a glycol chiller and argon gas and cover with plastic wrap. I have heard of some people using dry ice on top of the must and middle of the must and cover with plastic wrap and trash can cover. The dry ice will add a protection layer of gas and cool the top as well. It does not turn into water so it will not dilute your wine.

https://scottlab.com/gaia-500g-15686

 

[Guasto-IS]

Gaia yeast can be used to improve the odds of less spoiler organisms. This yeast will not create any caps nor any real sign of fermentation, so you will know that things are ok. GAIA only has tolerance to 3% alcohol so it will not compete with the yeast you inoculate for fermentation. It is a good idea to add 5% of the yeast that you want to inoculate when cold soaking so when you warm up you yeast has a head start. I also add a little extra nutrients in the beginning since both GAIA and your yeast will be using nutrients up to 3% alcohol.

I do use a big feeding trough from a tractor/farm store. I put the brute in and fill the trough up with ice. I add frozen gaterade bottles, use a glycol chiller and argon gas and cover with plastic wrap. I have heard of some people using dry ice on top of the must and middle of the must and cover with plastic wrap and trash can cover. The dry ice will add a protection layer of gas and cool the top as well. It does not turn into water so it will not dilute your wine.

https://scottlab.com/gaia-500g-15686

Can you recommend a good glycol chiller and cooling tube set-up for your cold soaks?

 

[Rotundifolia]

I use the glycol chiller that my husband got for beer making, so it might not be the best but it works. It also supports 2 trash cans at one time.

https://www.ssbrewtech.com/products/glycol-chiller-1-5hp

There is a pump that sits in the glycol chiller and pumps glycol through the immersion tubing coil.
https://spikebrewing.com/products/cooling-pump-1

The immersion chiller that I got was similar to this one. The downside of this chiller is the long arm. Does more chilling low. This is why I add the frozen gatorade bottles on top. The small chiller port is easy to cover with press and seal plastic wrap. I also wrap the brute with insulating foil from the big box hardware store

https://www.morebeer.com/products/stainless-steel-wort-chiller-brass-fittings-50-ft-12.html

There is insulated tubing that goes between the glycol chiller and the brute.
https://spikebrewing.com/products/insulated-tubing?var=6828615761979

This all could be hooked up to an ink bird (which my husband does for beer). I just let it go as low as I can get. I have yet to have freeze or close to freezing. It does keep it much cooler.

I get my grapes next Thursday so I will share a picture with it all set up. But hopefully this helps in the mean time.

 

[Guasto-IS]

Wow that is an amazing set-up - Congrats! Please update us on your 2024 wine making, I'm very interested to see the process and progress. My grapes (Cab/Merlot) are scheduled to arrive in early October and it would be great to try and implement a cold maceration set-up too.

 

[Snafflebit]

So, these are my over-simplified interpretations of the study. Your interpretation may vary.

• Skip the cold soak
• Skip the extended maceration
• Skip the rack/return
• Ferment warmer
• Blend the hard pressed wine into the free run wine according to my preferences.
• Continue to use enzymes
• Select the yeast very carefully
• Don’t do whole bunch fermentation

Just my .02.

This is my playbook this year also. I did one day cold soak. And I am fermenting hotter. One must reached the mid 80's F range. Best of luck to all!

 

[Rotundifolia]

Yes at the winemaking course in OR, the person who did a thesis on GAIA yeast stated that the studies do not show any material difference. He stated that his conversations with professional winemakers is that they like what they make and they cold soak. So they don't want to change. I love science and been part of the pharmaceutical and medical device industry in my career and I got to say science is not alway perfect. Since sensory can be subjective, I am sticking with the professional winemakers at the conference. I know many will not . Ask any winemaker and you will get 100 different opinions. (FYI - At the conference, the winemakers stated that they cold soak ideally for 5 days but a lot of time due to timing and facility constraints they often do a 3 day soak. Also they noted that the PH and TA changes as all the berries start breaking down.)

Anyways, attached are my pictures at day 3 in the cold soak process with GAIA yeast. The color looks great even though I had to Ameliarate. The glycol chiller is set to 30, room at 60 and top temp is 37.