Has anyone vacuum sealed yeast slurry? Is it too hard on the yeast?

[Horseflesh]

I've been saving slurry and repitching for a while now and it's been working out great, but I am interested in moving from jars to vacuum bags. I don't know how tolerant yeast are of low pressure, though.

I can seal a bag once the machine pumps down to at least 50-60% vacuum. It does not have to be a hard, outer-space vacuum where the slurry starts to boil! But even under the most mild cycle, the yeast will drop from normal pressure to about half pressure in about 5 seconds. Then the machine seals the bag and normal pressure is restored over several more seconds.

So is that ride too much for yeast? I have no idea.

Any ideas?

Any ideas for a quick and easy assay of yeast health, so I could compare a bagged batch to a jarred batch?

You may be asking, why not just use jars? A few reasons I want to use bags...

- Ease of use. No cleaning jars ever again, just sanitize a new bag and go.
- Cost. Bags are literally a few cents each. If I want to buy a few more jars of the right size that accounts for a LOT of bags.
- Space efficient, compared to jars.
- I have bags of various sizes and I can bag anywhere from a couple ounces to a half gallon of slurry.

I appreciate any feedback!

 

[PoppinCaps]

I think it's a great idea. If it were me, I would seal it once most of the liquid was removed, not pull a vacuum on it. Keep an eye on the bags in the fridge. They may expand with time as they off gas depending on the strain and how long they were in primary. I package in autoclaved retort pouches, and at such a high concentration, if every cell farts just a little, the bag is immediately inflated.

For yeast health, look up acidification power test for vitality, if you have a pH meter. If you have a scope, vital dyes are easier.

 

[Horseflesh]

My plan was to package with a lot of excess bag left, instead of trimming as closely as possible... exactly because of gas production. I'm imagining using quart bags most of the time, about half full of slurry with the rest left for gas. Based on my experience with plastic jars so far, that seems like it should be adequate for months of storage... Unless those jars have been leaking, which is possible.

The way my machine works, the sealer bar is powered by vacuum, so if you don't pump down at least ~50%, you can't seal. For food normally you want the bag pretty very snugly, but there are exceptions.

I do have a pH meter, thanks for that test reference, that's just what I am looking for.

 

[thekraken]

I'll be interested to hear your results.

Sounds like your sealer works different than mine. My seal and vacuum functions can work independently. I'm not sure i understand how you can vacuum much at all and not suck out all the liquid, much less 50%.

 

[Horseflesh]

I have a chamber-style sealer, so it doesn't suck air out the edge of the bag. That means it is easy to seal a bag of liquid, but the tradeoff is the sealer bar moves because of vacuum power.

Here's a video of a similar machine, queued up to good part.

EDIT: Aw, the forum strips the start time out. Skip to 50 seconds.

 

[Horseflesh]

Update: I wrote to White Labs and Imperial to see if they had anything to say. White Labs replied but I don't think they understood the question, saying that high pressure is bad for yeast health. Imperial also replied, in about 5 minutes, and said that the procedure I described would not harm the yeast. (They also clarified that though they package in pouches, partial vacuum is not part of the process.)

So, good news, and Imperial has great customer service!

 

[Smellyglove]

May I ask why you'd want to vacum it instead of using jars?

 

[bleme]

You may be asking, why not just use jars? A few reasons I want to use bags...

- Ease of use. No cleaning jars ever again, just sanitize a new bag and go.
- Cost. Bags are literally a few cents each. If I want to buy a few more jars of the right size that accounts for a LOT of bags.
- Space efficient, compared to jars.
- I have bags of various sizes and I can bag anywhere from a couple ounces to a half gallon of slurry.

 

[Horseflesh]

It's in the first post. But basically, I don't want to use glass because I am worried about yeast bombs. It's rare, but it can happen. And I can't find any good and cheap plastic jars I like. Jars need to be scrubbed, which is no fun. And finally, I have a really cool vacuum sealer and like a thousand easy-to-sanitize bags in many sizes, including huge. Jars offer me no advantage.

 

[YeastHerder]

I'm intrigued and going to try this with my vacuum sealer too. I've been using glass canning jars. I haven't had any bombs (yet) but release the pressure that builds in them, even at 4C, several times over the first few days before tightening them down for longer storage.

 

[thekraken]

I think I'm going to try this next time I harvest yest. Though, since I'm able with my machine I'll skip any attempt to vacuum the bags and just squeeze the air out and heat seal them.

 

[Smellyglove]

Hahaha! No wonder I sucked in school.

 

[Horseflesh]

I think I'm going to try this next time I harvest yest. Though, since I'm able with my machine I'll skip any attempt to vacuum the bags and just squeeze the air out and heat seal them.

As long as you don't suck anything into the machine it should work fine.

I have read that in an edge-sealing machine, if you hold the bag dangling over the edge of the counter you can suck out more of the air before you hit the seal button. Never tried it though, don't have that kind of machine.

 

[SEndorf]

My first thought is.... NO !!
When refrigerated yeast is brought back to room temp, you will get pressure and expansion.
I hope the bags don't blow up.
But I'd be interested to hear your results. The ease of it looks appealing.

 

[Horseflesh]

My hope is with enough slack in the bag, expansion won't be a problem.

Even if that is not the case I can probably dispense the yeast into a sanitized container for the warm-up period. But honestly, I have been pitching refrigerated yeast into wort for a while now because I am lazy or forget to let them warm up on the counter... and it has worked out OK so far.

Just gonna see what happens, now that I know the low-pressure time won't harm the yeast. I will post as I figure it out.

 

[enkamania]

My hope is with enough slack in the bag, expansion won't be a problem.

Even if that is not the case I can probably dispense the yeast into a sanitized container for the warm-up period. But honestly, I have been pitching refrigerated yeast into wort for a while now because I am lazy or forget to let them warm up on the counter... and it has worked out OK so far.

Just gonna see what happens, now that I know the low-pressure time won't harm the yeast. I will post as I figure it out.

Look forward to seeing how this turns out.

 

[SanPancho]

whats your sanitize process for the bags?

 

[Horseflesh]

Well I haven't done it yet, but the bags are food-grade and clean inside already... I'd probably spray StarSan inside and dump out the excess, just like any other container.

 

[Gentlemans_Ale]

Fwiw, I use polypropylene bottles and "autoclave" them in a pressure cooker for 15 mins at 15 psi. They're cheap on Amazon.

 

[SanPancho]

i assume your machine uses individual bags, as opposed to cut and seal bags we make from the rolls?

 

[Horseflesh]

Fwiw, I use polypropylene bottles and "autoclave" them in a pressure cooker for 15 mins at 15 psi. They're cheap on Amazon.

If you like them, can you post a link? I didn't find anything I loved when I looked, at least not at the price I wanted to pay.

i assume your machine uses individual bags, as opposed to cut and seal bags we make from the rolls?

Yep!

 

[Dcpcooks]

I don’t think the bag exploding is an issue. I see two other potential issues though.

The boil point of liquid in a vacuum drops, so you can briefly boil at room temp. Try sealing warm guacamole and you’ll see the blob come to life.

The yeast may suffer from some expansion as your pulling the vacuum. I’m not sure how dramatic that will be and if it will rupture the cells.

I’d expect you might be ok if your yeast is cold. I’d chill it to 32-33 degrees and use as little vac as possible.

I’d probably make a starter of fresh yeast and split it into a few different bags and see how they hold up.

 

[Horseflesh]

Yeast health is also my concern. Looks like I will just have to give it a try.

 

[Dcpcooks]

Keep us posted. I have a chamber vac at home and work. I’ve never used it for yeast storage but it’s the bomb for hops and odd size adjuncts.

 

[Horseflesh]

I use mine constantly, it's one of my best gadget purchases ever. I'll have to check the cycle counter but I bet I am getting close to 1,000.

 

[PoppinCaps]

My first thought is.... NO !!
When refrigerated yeast is brought back to room temp, you will get pressure and expansion.
I hope the bags don't blow up.
But I'd be interested to hear your results. The ease of it looks appealing.

As long as the yeast have stopped off gassing, this isn't an issue. For instance, treat a starter like a primary fermenter if you're going to seal it, let it go 10 days before sealing. If it gasses in the bag, it will fill, and only if it's under some pressure after that in the fridge will expansion at room temp have a big effect.

 

[day_trippr]

I have a FoodSaver that has vac-bagged a hella lot of home-grown hops over the years (70-80 pounds dry) but looking at it I can't imagine the epic mess that would ensue trying to vac-bag yeast. I keep about a dozen strains snoozing in pint mason jars...

Cheers!

 

[Horseflesh]

Kegged yesterday and made 2 vac bags of slurry. Each has about 1.5-2 cups in a quart bag so there is a lot of room left for gas expansion. It should be easy to see the bags swelling long before anything pops.

One was bagged at 66% vac, the other at 82%.

I'll post an update when I have some updates on vitality or messy explosions!

 

[opercularia]

Why vacuum seal? Is there any reason not to use ziplock bags? I use them all the time when freezing soups and simply squeeze any air out. Or is there an issue with permeability of the bags? Is this a problem with yeast?

 

[Horseflesh]

My vacuum bags are much cheaper than ziploc bags for starters. Vacuum bags don't require any special handling either, I can throw them around without a care, with no chance of a leak. They are also less permeable to oxygen. Not impermeable unless you buy special bags, but less so.

This isn't any more work than other methods, even if it may look like it, I swear! I do jars too but hope to switch to bags for reasons discussed above.

(For food storage, when you can use higher vacuum than you would with yeast, vacuum bags are incredible. A ziploc may look about the same but when you compare longevity and quality of stored food the difference is amazing. It is my favorite kitchen gadget by far.)

 

[Horseflesh]

A little update... After about 3 weeks of chilling in the bag, the slurry looks the same as it did on day 1, and I can detect no additional gas production. There may be some, but if so it's little enough that it just isn't apparent.

I haven't tried using any of this yeast yet, maybe it's all dead despite the reassurance Imperial gave me. :O But so far, so good.

 

[whosradl]

A little update... After about 3 weeks of chilling in the bag, the slurry looks the same as it did on day 1, and I can detect no additional gas production. There may be some, but if so it's little enough that it just isn't apparent.

I haven't tried using any of this yeast yet, maybe it's all dead despite the reassurance Imperial gave me. :O But so far, so good.

Curious how this process went for you and if you've kept up with it since your last post? Was the yeast usable again?

 

[Horseflesh]

Curious how this process went for you and if you've kept up with it since your last post? Was the yeast usable again?

It has been working great. Basically I can see no difference in vitality between jarred and vacuum bagged yeast. Sometimes the yeast produce enough gas that I need to burp and re-seal the bag, but it you have plenty of warning before things get exciting, and it only takes a minute to fix.

I have not yet tried the acid vitality test referenced above but sooner or later I will get around to trying that, or doing a vitality evaluation via staining when I get a microscope. That could prove I am crazy and this is a bad idea, but based on observing quality of fermentation, I see no problems so far.