slow fermentation

I have been homebrewing for the past few months and have had a constant problem with slow starts using liquid yeast (typically over 48 hours) The last batch started late and is is fermenting extremely weak even though I used a yeast energizer. I believe I aerate enough by stirring the wort vigorously and shaking the carboy after the wort is added. I don't ever have problems with dry yeast.
Any suggestions....help!

Aeration is the key in my book. I use O2 and inject it into the wort. Shaking and stiring just don't cut it. The other piece is volume of yeast needed. Those homebrew packs don't come close to the volume of yeast commercial brewers use. Repitch from patch to batch is one way and is what I do. I go for a number of generations without any problem.

Slow fermentations can make you anxious can't they?

Are you using a starter? I found that pitching while the yeast is still active really cut down my lag time and adding a little that little bit of additional wort didn't affect the flavor too much.

Indeed. I decided not too long ago to produce a last minute doppelbock, and didn't make a starter. My danged lager yeast took 6 days to start. Talk about being anxious.

I don't mean to sound ignorant but what is a sterter?

Take some DME, reconstitute with some water, boil to sterilize (essentially making wort), pitch your yeast in it, put an airlock on your container, and let the yeast start fermenting. It decreases lag time and increases number of pitchable yeast cells.

How long do I need to let this sit befory using it?

48 hours is best if you can plan that far ahead.

i've had better success with a large starter than just pouring the vial or smack pack in. but reusing the entire yeast cake gets you rocking almost as you're racking the wort atop it!!!

Thanks
This is the first time I have used this site. It has thrown some light on a long term problem I have been having, and fast.

I've given starters only a few hours prior to pitching and I see a big difference compared to not using a starter at all. You should give it more than that but I guess every little bit of a head start helps.

the best instructions I've seen on making a starter are here www.howtobrew.com. Palmer really walks you through the whole process. The Wyeast site also has a short description but it's not as comprehensive.

rohanski said:

How long do I need to let this sit befory using it?

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Wait until it hits high krauesen.

I usually make a starter the morning of brew day.

I boil 1 cup DME with 1 quart of water for 5 minutes, add it to a half gallon clear jug and affix an airlock.

In the meantime, I break the smack pack, let it swell for an hour or two.

I then add the yeast to the jug and begin brewing.

By the time I am done brewing, 3 or so hours later, the airlock on the starter jug is usually bubbling every 30 seconds or so.

When the wort is cool and ready for the yeast, I dump it in through a funnel into the carboy and affix an airlock. The batch is usually bubbling before I go to sleep.

Next morning? Tons of bubbles.

t1master said:

48 hours is best if you can plan that far ahead.

reusing the entire yeast cake gets you rocking almost as you're racking the wort atop it!!!

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Do you clean the yeast before adding the wort or do you pour right over the trub?

It is also really important that the wort is 65-75º, if you take Yeast that is room temp, dry, or out of the refrigerator and toss them into your wart that is 75-90º they go in to shock.

One thing also about aerating, the more O2 there is in the system the longer the yeast will convert sugar completely to CO2 and H2O, they need to be in an Anaerobic state due to the lack of O2 to produce EtOH (ethanol) and CO2. So if you oxygenate the system the yeast will be more active but produce less EtOH from the available sugar, but more bubbles.

I find it is best to have as little O2 in the system before pitching the yeast, but to try get the yeast in a linear growth rate at the time of pitching...basically activating the yeast 3-4hr before pitching (with dry Yeast re-Hydrate for 10-15min before adding to sugar solution), if you do this the yeast will be dividing at a rate of one division per 24hr and do this for 2-4 days until the system is saturated.

Some times the yeast are not as healthy from drying or whatever, they just take a while to get to the numbers necessary for a robust fermentation, but they will get there if you give them a chance.

P.S. you need 50million yeast cells/ 1ml of wort...

You do not have to clean yeast the first few times that you use it. I save the yeast cakes in Grolsch bottles and I just shake it up and pour it into a container with 1 pint water with 1/2 cup DME boiled into it just to get it active again( usually 24 hrs before brewing).

I only reuse yeast 3 times before I discard it and I have never had any bad tastes from using unwashed yeast. But I use hop sacks for my hops so the trub is not as bad as it could be. I would wash my yeast if it had hops in it. I fear that mixing the hops from the trub and the new batch would not be the best thing to do.