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KingCloyster
Forest Mushroom 🍄



Registered: 05/27/13
Posts: 597
Loc: Quetico, Canada
Last seen: 1 year, 4 months
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reheating agar, how long do i have until its no good?
#18428256 - 06/16/13 03:35 PM (10 years, 10 months ago) |
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Im going to pc some agar in a whiskey bottle with a tyvek and polyfill filter combo in the cap... Using 5 g Agar and 2.5 g LME for 250 mL of water. After the Agar has cooled and solidified, how long do I have, to boil and reheat the solid Agar before it goes bad?
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rew736
Your local stranger



Registered: 12/17/12
Posts: 1,145
Loc: New York, United States
Last seen: 3 years, 6 months
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Re: reheating agar, how long do i have until its no good? [Re: KingCloyster]
#18430063 - 06/16/13 10:25 PM (10 years, 10 months ago) |
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If the agar has no contams growing on the surface you are fine... I don't think it goes "bad" The only thin I have had happen too me is the agar dried out.
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matsc
Stranger



Registered: 09/17/12
Posts: 681
Loc: Arizona
Last seen: 6 months, 26 days
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Re: reheating agar, how long do i have until its no good? [Re: rew736]
#18430871 - 06/17/13 05:21 AM (10 years, 10 months ago) |
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What he said. As long as its clean and sealed well enough to keep moisture in, agar has a functionally infinite shelf life. Ive personally used a bottle of 15 year old agar and it worked well enough. Im sure given enough time that it might begin to degrade, but drying out is the bigger issue by far.
That said, repeated heating and cooling it CAN start to break things down. Its not too bad if you are careful with heat control but you still dont want to cycle the batch more than you have to.
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Stratman
virgin mycologist


Registered: 06/30/11
Posts: 294
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Re: reheating agar, how long do i have until its no good? [Re: matsc]
#18430933 - 06/17/13 06:22 AM (10 years, 10 months ago) |
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Quote:
matsc said: What he said. As long as its clean and sealed well enough to keep moisture in, agar has a functionally infinite shelf life. Ive personally used a bottle of 15 year old agar and it worked well enough. Im sure given enough time that it might begin to degrade, but drying out is the bigger issue by far.
That said, repeated heating and cooling it CAN start to break things down. Its not too bad if you are careful with heat control but you still dont want to cycle the batch more than you have to.
After you've prepared your dishes/slants, wouldn't it be standard procedure to re-sterilise agar before using it again after some period of time?
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matsc
Stranger



Registered: 09/17/12
Posts: 681
Loc: Arizona
Last seen: 6 months, 26 days
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Re: reheating agar, how long do i have until its no good? [Re: Stratman]
#18431689 - 06/17/13 12:06 PM (10 years, 10 months ago) |
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Standard procedure, sure, but bench monkeys get lazy too. I just tossed the bottle in the microwave for a couple minutes, cooled it to 48C in a water bath and then used it. I wiped the bottle down with ethanol before opening it, just to be careful. Yes it would make sense to re-autoclave the bottle after each use but as long as you follow good sterile technique it shouldnt be much of an issue.
That said, if it does become an issue, you should either re-evaluate your technique, or get in the habit of re-sterilizing often.
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ConcreteWaves



Registered: 01/08/13
Posts: 648
Loc: United States
Last seen: 1 year, 5 months
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Re: reheating agar, how long do i have until its no good? [Re: matsc]
#18432953 - 06/17/13 05:12 PM (10 years, 10 months ago) |
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Quote:
matsc said: What he said. As long as its clean and sealed well enough to keep moisture in, agar has a functionally infinite shelf life. Ive personally used a bottle of 15 year old agar and it worked well enough. Im sure given enough time that it might begin to degrade, but drying out is the bigger issue by far.
That said, repeated heating and cooling it CAN start to break things down. Its not too bad if you are careful with heat control but you still dont want to cycle the batch more than you have to.
 15 yr old? Damn son, the fuck you find that shit?
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matsc
Stranger



Registered: 09/17/12
Posts: 681
Loc: Arizona
Last seen: 6 months, 26 days
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Re: reheating agar, how long do i have until its no good? [Re: ConcreteWaves]
#18433092 - 06/17/13 05:43 PM (10 years, 10 months ago) |
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It was sitting on the back of a shelf in our labs stock room. I needed some corn meal agar for a particularly annoying Fusarium experiment, and we didnt have enough powder mix to make a batch. It was like half an hour before I would clock out for the day so I didnt want to visit each lab on the floor trying to beg some off them. I found the bottle on the back shelf, it was still sealed and hydrated, so I took a chance with it. I made more fresh agar a couple days later just in case, but the plates I poured worked fine.
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