Onset of Fermentation?

[mic]

What is considered the onset of fermentation? Is it when the first sign of bubbles in the airlock starts or is it when the active fermentation begins?

I pitched my yeast last night and when I woke up this morning I saw about one bubble a minute in the airlock. All the books I read say fermentation should start within 24 hours, but I wasn't sure if that meant active fermentation or not. I used white labs English Ale pitchable liquid yeast and I did not make a starter.

[YamahaXS]

yeah, its kind of a squishy thing... basically, fermentation has begun once C02 is being produced. your burbs should pick up over the next day or two, stay strong for a few days and then slow down as the fermentable sugars are consumed. if your pitch failed, then you would see no activity.

[quantum24]

i wouldnt worry yet, i never get a real active fermentation in the first 24 hrs, and i always use starters. if you're not chugging along in 48 hrs though you might have a problem. make sure the beer is warm enough , and dont hesitste to agiitate the yeast a few times in the first 30 hrs. hope this helps

[paul84043]

I have had two of my 9 batches that have had a long lag time until fermentation began.

I have always used liquid yeast, but haven't made a starter.
It's important to understand the yeast lifecycle, to understand the fermenataion process.
I found some real good links pretty quickly using Google.

I had originally thought that just throwing the yeast into the wort was really no different than letting it start and then pitching it, but it IS very different.

The yeast will not begin to consume the fermentable sugars in the wort until it's finished with it's first two phases of "life" which are multiplying and growing. They will do this until the supply of food (which at this point is NOT the wort) and oxygen, is taken up. This food is stored within the cell itself, but in the yeast packets, they add yeast energizer (glycogen) which the yeast uses to continue to multiply much faster than thier normal ability due to the abundant food supply. If you pitch your yeast too soon, the numbers are much smaller than if you let it "start" for several hours, then you remove (dilute) it's supercharged food supply and things slow down even more.
It still gets there eventually, it just takes longer and there are supposedly many by-products that begin to build up during the lag phase.
The "High Kreusen" (foaming frenzy) is basically the multiplying stage and does not indicate actual fermentation yet, but the numbers of the yeast increasing and growing exponentially.
When the oxygen reserves are used up, it signals the beginning of the fermantation phase which continues until the available, fermentable sugars are consumed. (This is when your Gravity readings will fall), then the yeast begin to die off slowly, or prepare to go dormant.

Here's a great link to some really good info, if anyone cares...

http://www.beer-brewing.com/brewers-yeast/brewers-yeast-cycle.htm

[mic]

Thanks for all the replies and info. The link was very helpful.

[gardenallyear]

I started my 4th batch in my new carboy on Saturday night. The kit I used this time had dry yeast and I pitched it directly into the carboy. Sunday morning the was a lot of activity and a steady bubble out of the airlock. It slowed down to a bubble every 30 seconds by Sunday night and is still at that pace tonight. I think everything is going okay, except my third batch using liquid yeast seemed to be much much more active. After reading this thread I think I may be okay. I used a starter on my first two batches with dry yeast and they didn't turn out - probably from bottling to early but I wanted to eliminate as much as possible on this batch.

[mic]

When I got home the airlock was going crazy and the foam head formed on top. This active stage did happen in under the 24 hours so I guess I'll relax and have a homebrew and try not to tap into this one too soon.

[paul84043]

Yeah, you've got a good three weeks before you can even think about testing this batch!