Canning unfermented wort for yeast farming?

Question

Canning is often used to preserve foods: the microorganisms inside mason jars are killed by a boiling water bath and sealed when removed. Small amounts of unfermented wort are useful when yeast farming. Has anyone tried canning unfermented wort so that you have a small amount on hand? Specifically I'm thinking of:

1. Preparing the mix like a yeast starter. Say 1/2 cup of dried malt extract to half a liter of water. (Per quart jar- leaving them roughly half full.)
2. Cap the jars with standard canning lids and bands.
3. Process in a boiling hot water bath for 15 minutes. (My thoughts: basically the same as boiling for 15 minutes.)
4. Remove from caner and let cool for 24 hours. (They should seal during this time.)

At this point you'd have jars of unfermented wort ready to use. So instead of going through the whole boiling process for a yeast starter, maybe you just sterile a flask and add in the wort and yeast.

Anyone try something like this? Thoughts or advice?

Answer 1

I do this about once or twice a year. I'm an all grain brewer, so I typically just brew a batch of base malt. You can do the same with buying some DME/LME and adding that to the right amount of water to get the SG around 1.035-1.040.

Your process sounds good, although I would probably blend all the DME and water at once so you can check the SG, and then use a bottling bucket to dispense to the jars.

You'll need a pressure cooker/canner - the boil must be under pressure at 15 psi / 1 atm. Wort pH is rarely under 4.5, so requires the higher boil temperature to destroy botulism-causing spores. This home canning page has more details on that.

It's also a good idea to add appropriate amount of yeast nutrient to the wort before canning. I always forget this when making a starter, so having it in the wort already (and sanitized) makes the day easier.

Using Concentrated Wort

Canning wort does take some time, especially if you do brew-sized 5 or 10 gallon batches. To make the canned wort go further, you can make the wort SG deliberately higher so you need less of it. You can then dilute the wort with the appropriate amount of water (assuming your water supply is sanitary) at the point of use. Some examples:

• If you make the wort SG 1.080 then dilute with the same amount of water. E.g. to make a 2 liter starter, take 1 can of wort and dilute with another quart of water.
• If you make the wort SG 1.060 then dilute with half as much again water. E.g. to make a 1.5 liter starter, take 1 can of wort and dilute with 1/2 quart of water.

The canned wort initially contains no oxygen, but there is some dissolved oxygen in the water, so adding water also gives a small initial boost to oxygen levels.

Answer 2

I do something similar with every batch, but I do not perform a full canning process. I normally calculate what I need for priming and for a starter. I sort of home-brewed the formulas...

Gyle for Prming (quarts) = [32 (if I want in ounces)] * (keg factor@) * (60/(1000 * (FG-1))) * (desired volumes)/2.8

@3/5 if following CP's recommendation in JoHB, I usually ignore this since I also bottle from the keg before carbing. Also, CP's formula this is based on is tuned to 2.8 volumes, hence the volume factor.

Starter oz = (64-16@@)*(35/(1000 * (FG-1))

@@ This just gets me close to the final desired concentration in 48 oz (for some head space in a growler).

I just store these in canning jars in the fridge, and then..

Before priming, I boil gyle, let it cool and pour in keg. (After which I immediately bottle a 12 pack or so for cellaring/comps).

Before starting a starter, I boil the starter wort, adding about a pint of water (enough to bring it to about 64 oz) for boil off and make sure it's between 1.030 and 1.040 (adding water or boiling longer as necessary), allow to cool and pitch. This gives me ~48oz of wort to pitch in and I use growlers for my starter.

I think your method would work fine, but I do think it's easier to just refrigerate the wort and boil it before use.