2008 Sa Xmas Case Swap

[drsmurto]

I would recommend that you NOT make a starter at 30C for a lager. After all, you are trying to get the optimal yeast conditions for 10C.

15C (Max) would be my recommendation for a lager yeast culture. YMMV

cheers

Darren

You are making yeast, not beer.

I make all my starters - ale or lager at temps approaching 30C. Had some long chats with mates doing genetics PhDs at the Uni of Adelaide, 25-30C = business time for yeast.

I then let it settle and slowly cool to room temp, then chill to ca. 1C , pour of the 'beer', let it come back to ferment temp and only pitch the slurry. Some of the more flocculating yeasts i dont bother to chill as 24h at room temp (~18C)

 

[Darren]

Hey Dr. S,
I did my PhD in microbiology

I agree that yeast grow better at 30C. However, they adjust their metabolic rates during succesive cell division and become "climatised" to that temp.

Once they are dumped into 10 C wort they have to reconfigure their gene expression profiles to operate efficiently at the lower temp.

Remember you are making yeast to make beer. Most laboratory yeast cultures are used to express recombinant proteins where 30C is the best temp.

cheers

Darren

 

[drsmurto]

Ah, yes, you told me what your PhD was in a while back.... man i have the memory of a goldfish.

So what are they likely to do after all these change in temps?

Bad esters? Lower attenuation? Longer lag time?

 

[Darren]

All of the above I would say

 

[~MikE]

following up on the slanting demo, for those that missed it, i opened a blank slant and left it on the bench to see what would happen. well, here's a photo. by my count there's seven fungal colonies, and a smaller unknown one. so yeah, over several minutes open to the elements only 8 viable cells/spores made their way onto the slant. of course if i'd have touched it or breathed on it, there'd be much much more, but hopefully this should quell any unease about infecting your slants

 

[buttersd70]

all that edu-ma-cation, and still has trouble attaching a pic. :lol:

So where is this photo, mike? <insert evil chuckle>

 

[~MikE]

is it not showing up for you or something?
here's a link
http://img257.imageshack.us/img257/3003/slantxr8.jpg

 

[buttersd70]

weird....its showing now. I retract my earlier statement. :lol:

 

[drsmurto]

Is that all the photos? No shots of cricket. The late night shenanigans?

 

[Adamt]

Strangely enough I can't remember who else had a camera.

 

[buttersd70]

All the shots I took are in the gallery....I know Mike had a camera, any shots?

 

[Darren]

by my count there's seven fungal colonies, and a smaller unknown one. so yeah, over several minutes open to the elements only 8 viable cells/spores made their way onto the slant. of course if i'd have touched it or breathed on it, there'd be much much more, but hopefully this should quell any unease about infecting your slants

Hi Mike,

Only 8 in a couple of minutes? How many do you think would be a problem?

cheers

Darren

Moderators: Feel free to move to new thread if needed

 

[~MikE]

Hi Mike,

Only 8 in a couple of minutes? How many do you think would be a problem?

cheers

Darren

Moderators: Feel free to move to new thread if needed

um, only one would ruin a slant. but it took a couple of minutes with the slant exposed to the air to get 8 viable cells to land on it. was trying to illustrate that if you do what i did, and only have it open for the second it takes to inoculate with slurry - shouldn't have any. was also interested to see what would grow on it.
mike

 

[mickoz]

um, only one would ruin a slant. but it took a couple of minutes with the slant exposed to the air to get 8 viable cells to land on it. was trying to illustrate that if you do what i did, and only have it open for the second it takes to inoculate with slurry - shouldn't have any. was also interested to see what would grow on it.
mike

Sort of explains how I get away with using the urine sample jars for slanting, they have an enormous mouth compared to a test tube and I am not anally cautious about hygiene when I'm slanting. I usually pop the lid, tip any moisture out then pick some yeast using a metho dunked needle and place it on the agar then close the lid. I guess the whole process takes about 4 secs. I've done about 50 slants so far and they all look clean as a whistle.

Mick

 

[Darren]

um, only one would ruin a slant. but it took a couple of minutes with the slant exposed to the air to get 8 viable cells to land on it. was trying to illustrate that if you do what i did, and only have it open for the second it takes to inoculate with slurry - shouldn't have any. was also interested to see what would grow on it.
mike

Hi Mike,

Do you still have that plate?

I would be interested in seeing another pic of how the growth has progressed?

cheers

Darren