I started making slants just over a year ago.
Mostly successful plus a few lovely blue green moulds that would not look out of place in the cheese section of a delicatessen shop.
When I prep new blank slants I leave them at room temperature for a fortnight to see if anything grows, if not I assume that they are sterile and pop them into storage in the fridge for future use.
Recently had some that I left out (forgot about) for four weeks. They had been OK after a fortnight but the extra fortnight gave the unwanted moulds a chance to thrive and about a quarter of them had grown moulds.
This is fine by me, as this is why I leave them out of the fridge for a fortnight to test the sterility of my preparations.
I have read lots of posts on this and other forums and can only remember once seeing anyone advocating leaving slants and plates out of the fridge for the first couple of weeks to see if all is well.
QUESTION If anyone else leaves slants out for testing , how long is the norm.
Cheers All
Testing Blank Yeast Slants
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- Piss Artist
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Re: Testing Blank Yeast Slants
Mine don't go into the fridge untill they have yeast on them.
That can be 3 months+ at room temperature.
Never had any contaminations yet.
How are you preparing the slants?
That can be 3 months+ at room temperature.
Never had any contaminations yet.
How are you preparing the slants?
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- Piss Artist
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Re: Testing Blank Yeast Slants
I am using tubes recommended on one of the posts here , supposed to be autoclavable.
The tubes are autoclavable, but the screw on caps have a foam liner that expands like a prawn cracker if it goes into the pressure cooker.
Up to now I have given the tubes of liquid twenty minutes in the pressure cooker . Piece of loose aluminium foil over the tops to keep out any drips from the lid.
The caps have been soaked in sodium met. for twenty minutes, followed by a quick rinse under the tap.
I have been using Starsan for the last couple of months to keep bottles and gear clean. Thinking of using this for the caps in future.
When I coat the slants with yeast I do that in the heat of the gas stove. Accompanied by the smell of singed knuckle hairs.
I think the caps are probably the week point in my routine.
It could be the rinse under the kitchen tap.
The next batch that I make I will soak the caps in Starsan and just shake the Starsan off with no tap water rinse.
I don't know if yeast will grow in the presence of Starsan.
The tiny amount of Starsan left in such a small volume tube may be detrimental to good yeast growth.
Most batches of slants that I make are fine. It is just the odd rogue batch that I loose about a quarter to infection.
Cheers.
The tubes are autoclavable, but the screw on caps have a foam liner that expands like a prawn cracker if it goes into the pressure cooker.
Up to now I have given the tubes of liquid twenty minutes in the pressure cooker . Piece of loose aluminium foil over the tops to keep out any drips from the lid.
The caps have been soaked in sodium met. for twenty minutes, followed by a quick rinse under the tap.
I have been using Starsan for the last couple of months to keep bottles and gear clean. Thinking of using this for the caps in future.
When I coat the slants with yeast I do that in the heat of the gas stove. Accompanied by the smell of singed knuckle hairs.
I think the caps are probably the week point in my routine.
It could be the rinse under the kitchen tap.
The next batch that I make I will soak the caps in Starsan and just shake the Starsan off with no tap water rinse.
I don't know if yeast will grow in the presence of Starsan.
The tiny amount of Starsan left in such a small volume tube may be detrimental to good yeast growth.
Most batches of slants that I make are fine. It is just the odd rogue batch that I loose about a quarter to infection.
Cheers.
Re: Testing Blank Yeast Slants
Sounds like exactly the same process as mine except my lids are autoclavable and sit loosely on the tubes in the pressure cooker.
Would be interesting to find out whether Starsan on the lids allows the yeast to grow, if it wasn't a yeast slant, then that is just the sort of application where I'd be hoping the Starsan would stop any growth, but if it just stays on the cap and doesn't run down onto the slant it might be OK. Let us know!
At least it seems like you've found any contaminated slants before using them anyway.
Would be interesting to find out whether Starsan on the lids allows the yeast to grow, if it wasn't a yeast slant, then that is just the sort of application where I'd be hoping the Starsan would stop any growth, but if it just stays on the cap and doesn't run down onto the slant it might be OK. Let us know!
At least it seems like you've found any contaminated slants before using them anyway.
- barneey
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Re: Testing Blank Yeast Slants
Even though some tubes / lids may look the same they aren't......
Hair of the dog, bacon, butty.
Hops, cider pips & hello.
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Hops, cider pips & hello.
Name the Movie + song :)
Re: Testing Blank Yeast Slants
You should be able to leave your slant out in the open forever without any signs of infection. The extra week only highlighted an error in your technique.
The plastic autoclavable vial lids do inflate but still work if you leave them on very loose whilst autoclaving and lock them tight once cooled. These are the same ones used by Brewlabs.
The vials should be incubated at 25C for three days to check for infection. I do that in my brew fridge. I then lock the lids down tight and put them in the fridge.
The plastic autoclavable vial lids do inflate but still work if you leave them on very loose whilst autoclaving and lock them tight once cooled. These are the same ones used by Brewlabs.
The vials should be incubated at 25C for three days to check for infection. I do that in my brew fridge. I then lock the lids down tight and put them in the fridge.