Cold Soak: Dry Ice vs. CO2

I’ll be working with an open top fermenter, e.g., T-bin, and am wondering what the difference would be in effectiveness between the use of dry ice for a cold soak, pre-ferment, versus blanketing with CO2. I’ll be covering the tank with construction plastic and securing that in place with bungie cords or tape. Thanks for any help.

Well obviously, the dry ice will keep the fruit colder, whereas the gas will not. It depends on how long you are going to cold soak, and the kind of temps you want your fruit kept at. If you are going to do an extended soak, you might want your fruit extra cold, so you can layer dry ice in. If you just use a little on top, it’s not going to effect temps that much. Depending on how you have your bin covered, you have to also take into account how to get the CO2 in- will it be physically easier to gas? You would only have to have a small opening in your covering to gas, as opposed to taking more of your covering off to get enough dry ice in.

When the places I’ve worked with had both available, we’ve added dry ice (either pellets or broken up blocks) immediately following crush and punched into the must. After that initial dry ice add, we gassed with CO2 once a day until fermentation started but didn’t add any more dry ice. At those times, we took the bin cover off to measure brix and temp, and to check for any mold formation and gently stir up the must a little so that was not an issue for us. As Linda wrote, the temperature you want in the must is the main factor.

As mentioned above just keep the head space void of o2.
You need to start with cold fruit and keep in a very cool area to keep a t-bin cold enough for a proper cold soak. It will take a lot of dry ice to get the must cold and maintain it that way in an area much warmer than your target must temp.

With PN I use all t-bins. Don’t do any formal cold soak pre or post, wild yeast, partial whole clusters and average 21 days on skins. However I do get the fruit in cold (42-44) post destemming. I also keep the winery cold (60 or so with night time ventilation) so for the first few days until lots of bubble are forming I keep the head space gassed. I use small plastic guacamole bowls filled with dry ice 2x daily (after punchdowns and temp checks) and set on top of the must to keep O2 out. I have fabric fermentor covers for the t-bins. No moldy berries since going to this regime.

Guacamole bowls. Is that industry standard? [snort.gif]

Linda, Ken, and Joe, thanks for all the great information.
Joe, in using the T-bins, do you ever wish they’d make 'em with a bottom release valve that could be coupled to a hose?
Have a great harvest all.
n.

I love them. There just the right size to last 12 hours or so when full. They also are thick food grade plastic so that the skins don’t get frostbite. I don’t like dry ice to touch skins, I hate the taste of the burn/frostbite the skins get. They were cheap at Safeway and come in cool party colors!

I have seen folks fit a macro bin with fitting and valve to use to drain tanks. I don’t think you will have good luck with the double wall. There are the big mack’s (macro 48 I think) that are bigger 1.5 ton capacity and single wall. I use this

http://morewinepro.com/products/perforated-suction-tube.htmlto pull the free run then forklift rotate the skins to the basket press. People also use this for pump overs. I don’t do those and I would not like to clean it between each fermentor.

There is a reason t-bins are $3-400. If you want options like that on a stainless tank be ready to spend $3-5,000 for each fermentor.