Expert: John Snyder - 9/5/2004

Question
-------------------------
Followup To
Question -
Hi, John,

I just made a batch of wort with what may have been old yeast. Anyway, the wort didn't appear to ferment--not a burble or bubble did I hear or see. What can I do to save the situation? Do I heat up the wort again and put in fresh yeast?Thanks.

Tom
Answer -
  Personally,i wouldn't heat up the wort again.With yeast already in the wort,and hops,you would be imparting all kinds of off tastes in the final product,during the re-heating.the best solution would be to repitch,the wort,if the conditions were right.
How long has the fermentation time been?Unfermented wort can have a short stable life,a day or less,or up to 1 week,depending on it's handling,and equipment sanitation.
If you decide to repitch the wort with fresh yeast,add the yeast at transfer of the wort to a clean tank,decanting off the old yeast,as much as possible.Rouse the yeast and wort,by sloshing,to introduce some air to start the fermentation.The wort temperature should be in the 50 to 70 F range.

Are you sure the problem was the yeast?
What was your wort temperature at time you added the yeast?
What was the gravity?What is it now?
Was there proper aeration?
Was there any problem in the brewing process?
What was the fermenting vessel's ambient temperature.?
You can check the yeast you used,adding some to a little warm water,80-90 F,and a little sugar,keep check on it,and in 20mins+ or-you should see some bubble formation,and a little foaming,if the yeast was ok.

Under what conditions do you keep your yeast?

Any additional info,you could provide me would be of help,in trying to provide you with a more accurate diagnosis of your problem.

         John


I realized after I sent the last message I hadn't given you very precise information, John. Let me answer your questions:

--I was given a kit that might have sat around several years, probably in a cellar;

--I sprinkled on the yeast that came with the kit as I usually do (haven't had a problem before over about a dozen batches): a few minutes after pouring the wort into the fermentation bucket, which sums up my aeration stage as well;

--I'm quite scrupulous about cleanliness, although I didn't have any of the sanitation packets this time and to clean everything used a diluted bleach solution (half a capful in about a gallon and half of warm water

--I'm up in Maine, and the ambient temperature for the fermentation has ranged from 60-73, I'd say. The wort has been out for four days now.

--I'm afraid I'm ignorant about "gravity," although I'd be glad to learn about it.

From what you wrote, it sounds like repitching (I didn't know that term) is the best option, as long as the wort hasn't gone bad. Is there an easy way to tell if it has? For that matter, can I tell if the wort has in fact fermented? Maybe I just missed the bubbling. I don't any of the original yeast left so I can't test it as you suggested, but it does sound like I should move fast in case the wort hasn't been fermenting.

Thanks for your help, John.

Answer
Most likely your yeast wasn't viable enough,based on the age of it.You could still test it,by retrieving it from the wort,then testing it.

The best way to check the wort now,would be to taste it.The wort should be sweet,and full tasting.Any sour,rancid,or putrid taste,indicates the wort is spoiled.

The fermentation ambient temp,you mentioned is perfectly fine.

Gravity is measured by a hydrometer.It measures the sugar content of the wort.the measurement is made before,then after fermentation.The difference can then be calculated to give you the alcohol content of the beer,at end of fermentation.A hydrometer,with a temp correction measurement can be bought for around $15.

Did you get any type of brownish scum(foam type)on your wort,about 24 to 48hrs,after yeast addition?If so,there is some fermentation going on.It may be very sluggish,because of the yeast.Repitching is still the best choice,if the wort tastes ok.If you do notice this formation,just transfer and add more yeast,but don't decant the yeast,already in the wort.

A hydrometer is a very important tool.

Any further advice needed,please let me now,i will be glad to assist you.

         John