Making Agar Slants (Slopes) - In Pictures

[floydmeddler]

Right, I've bought me some agar. Look forward to trying it out using your instructions. Was a little expensive but should last for ages going by your quantities.

Cheers!

[Wolfy]

Is there any harm in saving your old used slants and melting them down to use again?

Given the risk of yeast-strain-cross-contamination, the possibility of other infections, contamination or any manner of things going wrong, I'd have to ask why you'd want to do that?
10ml of wort/agar mix has to cost virtually nothing compared to the slight risk of having something go wrong by reusing it (even if I try I can never remove all the yeast, and usually do not bother keeping the slants sanitized once they have been used).

But I guess the yeast have only grown on the surface so if your sterilisation procedure was top-notch (which mine is not) it may be possible.
I've poured slants that solidify before I get to 'autoclave' them, but they liquefy and then re-set without any problem, so the theory is valid, just the risk of contamination is what I'd be concerned about.

Right, I've bought me some agar. Look forward to trying it out using your instructions. Was a little expensive but should last for ages going by your quantities.

The (25g) packet in my first picture cost the equivalent of 0.93 GBP and is enough for about 160 slants, by the sound of it you you got a life-time supply.

[floydmeddler]

I paid £4.50 for 28g. Bought this stuff:



160 slants is a life time supply for me as I don't add wort to the slant when wanting to use it. I Scrape some off the surface and add it to a mini wort.

Look forward to trying this stuff. Gelatine has been great but gets a little fragile.

[Wolfy]

I paid £4.50 for 28g. Bought this stuff:
...
160 slants is a life time supply for me as I don't add wort to the slant when wanting to use it. I Scrape some off the surface and add it to a mini wort.

OK, now I understand the reason for conserving and reusing slants.

[johnmac]

Given the risk of yeast-strain-cross-contamination, the possibility of other infections, contamination

What sort of yeast or infection will survive the autoclave?

[Wolfy]

What sort of yeast or infection will survive the autoclave?

A real autoclave, probably not much, which is how/why/what they are used for.
However, a pressure cooker or other similar home/type 'autoclave', and non-sterile home-type work environment, as per the pictures (and AFIK what many Home Brewers use), I don't know, but personally I see no benefit from taking the risk, either in terms of time or money.

[Gricey]

http://cgi.ebay.co.uk/18-Plastic-Test-t ... 1734wt_913

Those look like the PP tubes. Dunno if I want to drop £20 though.

[Wolfy]

Those look like the PP tubes. Dunno if I want to drop £20 though.

So go for 10 @ £4.99, flat bottomed so you don't really need the stand, I have no affiliation with the seller, but his stuff has often been linked from these forums.

[Gricey]

That's more like it!

edit: they're 30ml rather than 50ml, is that a big deal?

[Wolfy]

The plastic ones in the picture in the first post (which I edited to make it clear) are 30ml, so they are ideal/the same.

[Gricey]

Bonzer, cheers

[MARMITE]

Made my slants last night and all seems to have gone smoothly.At the moment they are at 20-25c for proving.I have some plastic loops which presumably are sterile until I open the packet.Should I sterilize the loops with something like vodka before use?.Also some detailed advice on how to grow the cultures up would be very much appreciated.

[Wolfy]

I used to dip my plastic loop in vodka after I ran out of denatured (rubbing) alcohol which (I think) is a better option, but metal loops are easier to sterilise (via heat) and hence better IMHO.
I've got a few more pics, so plan to do another set of posts with how I make and use slants, but really you just inoculate them with your loop and let them sit and grow for a few days/week and thats it.

[leedsbrew]

Thanks for such an informative thread wolfy!

Ps, love the sig, APC have to be one of my favourite bands ever!

[mentaldental]

Back in my youth I used a hot air sterilizer in a clinical setting. It was basically just an electric oven. Hot air is an effective but limited method of sterilization (no good for plastics etc). It's biggest drawback compared to the now ubiquitous autoclave is time:

Hot Air
160°C for 2 hours
180°C for 1 hour

Autoclave
135°C (2 bar) 3 minutes
121°C (1 bar) 20 minutes

If you use a pressure cooker as an "autoclave" remember that actually it isn't an autoclave. In particular you will rely on the steam displacing the air from the cooker. Until all the air is gone sterilization won't start. So allow time for this to happen and also make sure that any hollow vessels (pots, tubes etc) are open to allow access for the steam.

Also don't forget the dishwasher, if you have one. Medical instrument washers are dish washers in all but name (although never tell the manufacturer's agent that ). They get the contents so clean that they are sterile in everything but name. In medicine they are important because they remove (non-living) prions which are uneffected by an autoclave. I have used a dishwasher to disinfect bottles and the beer has been sound after 12 months, so it seems to work.