calculation question re:yeast

[fred588]

I'd like to calculate the actual cost of using yeast for carbonation. For that I have two questions. First, how many packages of yeast (or how much of any other source of yeast) are required for a, say, five gallon batch. Second, does anyone attempt to continuously culture, or otherwise extend, a "package" of yeast?
I apologize in advance if the question is stupid.

 

[JPennington]

Admittedly, I'm still new to the hobby, but most of the soda recipes I've seen so far call for a pretty reasonable amount of yeast. For example, the recipe I used for the batch of root beer I recently made called for 1/8 to 1/4 tsp of rehydrated dry yeast for a 1 Gallon batch. That was a pretty small fraction of the package's total contents, and I purchased the yeast for $0.99/pack. Even the 4 Gallon batch called for 1/2 to 1 Tbsp, which shouldn't be more than one pack.

I can't say anything about culturing the yeast, however, as I've never attempted anything like that.

 

[Yooper]

Alot of neutral wine yeasts are 59-70 cents for a 5 or 6 gram package.

I generally use a tiny bit, but I only carb up about a gallon or so. If I'm doing more than that, I would keg it and use c02 since you need the c02 to serve it anyway.

For a gallon or so, you need about 1/8 teaspoon, so maybe 1/10(?) of a package.

So, you could probably use 1 package for 6 gallons of soda, just to make it easy. You could probably use less but I wouldn't mess around with such small amounts.

I would definitely not try to save yeast from the bottom of a soda keg to reuse- it would be a huge pain and a risk of contamination to save 70 cents.

 

[fred588]

Thanks for the answers. I am not trying to save money here. I carbonate my soft drinks from a 10 pound tank of gas. What I am doing with the information is simply calculating what the cost actually is for the yeast, so that can be compared to the cost for the gas. I get a tank filled for about $40.00 and that is good for about 850 liters, which computes to a little under $.05 per liter. Using the price of $.99 for a package of yeast and using 4 gallons as the output, that equates to $.99 for roughly 16 liters, or about $.06 per liter.