Sterilise jars in oven?

[Jocky]

I was going to wash some yeast next week for use in a future brew.

To sterilise the jars I was going to use, in the absence of an autoclave or pressure cooker is it preferable to boil the glass jars I was going to use, or just put them in the oven at 130C for 20 minutes?

Or I can do one and then the other, a day apart?

[masterosouffle]

You will be okay with the oven but will need to do for longer, over an hour if memory serves me right

[Twistedfinger]

Dry heat sterilising takes at least 2 hours at 160c

[Jocky]

Is boiling more effective?

[Aleman]

Wet heat is much more effective but for sterilisation purposes you need to use steam at 121C for 15 minutes . . . Something like 70 minutes at 100C IIRC.

The issue with jars in the oven at 180C is that you can ruin the temper on them . . .not necessarily an issue for yeast culturing stuff but for bottles to be under pressure it is to be avoided.

[Jocky]

Ah. I'll get a cheap pressure cooker at some point soon then.

[Dunk]

You have to sterilise the lids of the jars too and the last time I put them In an oven at 150deg the rubber sealant melted. Oops. I've washed yeast in jars that we're simply boiled in a pan with no,issues. Yet.

[charliemartin]

I use a microwave baby bottle steriliser. Pour boiling water from kettle in then microwave on high for 5 minutes.
Haven't had any issues so far.

Cheers,
Charliemartin

[Jocky]

I use a microwave baby bottle steriliser. Pour boiling water from kettle in then microwave on high for 5 minutes.
Haven't had any issues so far.

Cheers,
Charliemartin

What are you sterilising? Jar lids will cause microwave to explode.

Or do you just sterilise the jars and keep the yeast out of contact with the lids?

[YeastWhisperer]

There is absolutely no justifiable reason to rinse yeast with boiled water, as doing so has the potential to do more harm than good. Green beer contains ethanol. It also has a relatively low pH. Both of these attributes protect a cropped culture from infection.

[Jocky]

There is absolutely no justifiable reason to rinse yeast with boiled water, as doing so has the potential to do more harm than good. Green beer contains ethanol. It also has a relatively low pH. Both of these attributes protect a cropped culture from infection.

What's your preferred technique?

My understanding was that boiling was also to remove oxygen... I've no idea how that helps though.

[YeastWhisperer]

I do not rinse yeast with boiled water. It is not necessary, nor is it all that beneficial. I just crop and repitch. My preferred way to bottom crop is to leave small amount of liquid behind while racking. I use this liquid to suspend the solids. I usually wait a couple of minutes for the heaviest particulate matter to settle out before decanting the yeast that is still in suspension into a sanitized 500ml Erlenmeyer flask (I use a #7 rubber stopper and an air lock). While many people attempt to crop several containers of yeast from a batch, I prefer to repitch serially if I am reusing a strain for a period of time. Serially repitching a strain ensures a high level of yeast cell viability. It also forces a strain to adjust to one's brewery (it's basically natural selection in action). The thing that limits repitching in a home brewery is infection from house microflora; therefore, it pays to be an anal retentive brewer when repitching yeast.

With that said, storing yeast rinsed with boiled water under boiled water is not a viable long-term storage method. Those who believe that it is a proper long-term yeast storage strategy are fooling themselves. The two long-term storage strategies available to the amateur brewer are agar slants (a.k.a. slopes) and cryopreservation (a.k.a. freezing yeast cultures in a solution that contains glycerol to prevent cell rupture). Without a freezer capable of at least -80C (yeast cultures will remain stable almost indefinitely when stored at -80C), agar slants offer the greatest long-term storage. Yeast stored on properly-prepared agar slants will remain viable for about two years as long as the slants are stored at 4C. I maintained several cultures for 10 years on agar slants in my first yeast bank. My preferred long-term storage medium for slants is solid MYGP. I prepare my own MYGP media from scratch using 1% dextrose, 0.3% yeast extract, 0.3% malt extract, 0.5% soytone (I avoid using peptone due to BSE), and 1.5% agar. I have also used straight solidified 5% (1.020) wort for slants (all one needs to make solid wort is powdered agar or agar flakes and dry malt extract). However, I have found that MYGP is better for storage beyond six months.

[charliemartin]

I use a microwave baby bottle steriliser. Pour boiling water from kettle in then microwave on high for 5 minutes.
Haven't had any issues so far.

Cheers,
Charliemartin

What are you sterilising? Jar lids will cause microwave to explode.

Or do you just sterilise the jars and keep the yeast out of contact with the lids?

Hi Jocky,
Sorry for late reply to this, just noticed your post when checking my old posts. I can assure you that the lids do not cause the microwave to explode. I have done this several times with no ill effects, no sparks or anything. It is either because the lid is encased in the plastic sterilising unit or perhaps microwave ovens have been vastly improved in recent years. However, if my microwave blows up I'll let you know!

Cheers,
Charliemartin