FYI

[Dennerle]

For those DIYing CO2, please note that water temperature 37 degree celcius and above kill yeast. So try to keep below 37 degree celcius

[juggler]

Now I know yeast can't grow on me...

Seriously, Singapore's temperature has not gone above its highest record of around 35C so far. So not to worry unless you are placing the yeast bottle near your stove.

[vinz]

The problem is some ppl use hot water to dissolve the sugar, then put the yeast in immediately... []

Maybe that's why some ppl can't get their DIY CO2 started.

[Plantbrain]

I teach an enzyme kinetics lab to students every semester, we incubate our yeast, S. ceversiae, at a number of temperatures for one of our treatments.

Often the students find the optimal reaction rate to be in the 40-55C range with 50-55C being the most common on the labs. We've done perhaps 200+ labs in water bath controller temperature chambers with controls etc.

I'll move elsewhere if it gets 50C+ for long

Generally normal hot summer weather is not high enough to cause problems in the shade. Desert temperatures in some regions might cause some problems and decline if left out in the sun.

I have noticed large declines in CO2 production in cooler weather but many folks add their DIY CO2 to a warm water bath with a heater or I like to place the DIY bottle on the lighting ballast since it's "on" when I need the CO2. This amplifies the production of the yeast when the aquarist needs it and lowers it when they do not.

This in practical terms seems to work well for cooler areas, warmer tropical areas have nothing to fear unless it gets extremely hot(over 55C).

Regards,
Tom Barr

[CK Yeo]

this is interesting. None of the yeast research labs here grow yeast >40C (at least not that I know of). Routinely, they are culture at 30C. higher if they are playing with some temp sensitive mutants, or heat-shock...

Tom, what were you assaying for in those experiements? cell growth? or Enzyme activity?

Anyway, I think it is a good idea to cool the solution to room temp first, if you are using hot water to dissolve the sugar.

ck

[Plantbrain]

I was not saying anything about the "culturing" of yeast.

I was specific. Maximum _CO2 production rates_.

This is higher than one might predict. We use various carbohydrates for each student(5 and one control, water). Sucrose is the highest production followed by Glucose and Fructose respectively.
We test this species of yeast ability to utilize these substrates for various pH's(4-4.5-5-5.5-6-6.5) along with 15C, 30C, 45C, 55C, 60C, 70C.
CO2 is the end product that we use to measure the yeast abilty to utilize a substrate under a given condition.

The labs are quite consistent year after year. Most students predict lower temperatures but find it 45-55C as they do the lab and the report.
60C and certainly at 70C, you see little if any CO2 production due to denaturization of the enzymes.

But there's not much difference in the basic procedures one would use with DIY CO2. Just reporting what you can do at home if you want. I have 750 students a semester come through the department doing the same lab. The other teachers have the same results as I do.
So that's close to 1500 runs each year with good old bread yeast, tap water and sucrose.

Both total CO2 evolved and rate are tested for.

I don't suggest folks to add hot water to their DIY, but I'm also saying that warm weather is not going to cause a problem, unless you get very very warm

Cold weather will cause far more issues generally.
Many folks in the USA use warm water baths to elevate their brew temps to about 40C or so.

Regards,
Tom Barr

[loupgarou]

on a side note, I don't think its appropiate for someone who doesn't speak for a company to use the company name and logo,

I think there are also legal issues with that.

eg: misrepresentation, fraud etc