Yeast starter assesment

Ideally you want a krausen to form, as a minimum there should be evidence of CO2 off-gassing. I have had minimal/missed krausen but I've always had a thick foamy head occur when giving the flask a heavy shake. This head becomes progressively smaller as the growth phase of the yeast is completed. If only 10 hours there may still be hope, but you have to have some fermentation activity (as evidenced by bubbles when shaking). Using yeast nutrient helps yeast get in gear as does oxygen, temp should be mid-70s.

Depending on the quantity of yeast, a pint may be way too low to make a proper starter. You should try and estimate the number of yeast in your slurry and size your starter appropriately. If too small, you get little growth from your little friends. Consider adding another pint if no activity occurs (really depends on yeast count).

Here's what you're looking for after a hard shake:


I have had yeast that had previously performed well refuse to wake up from their nap. Better to know now than when you're staring over a bucket of wort.

 

To be sure, your slurry is not just dregs but you have made it active before? If so, my technique is to estimate the number of cells by quantity of slurry. I use the Wyeast guidelines; 1.2 billion cells/ml, then adjust viability for time. In your case you have almost two months of inactivity, so almost half of the yeasties are permanently asleep. These are rough estimates . . . if any microbiologists with better ideas are lurking, please chime in.

One other question, I'm guessing you are not using a stir plate, correct? A stir bar will drive the CO2 out of suspension (desirable) and you will see little to none of the bubbles pictured above. If you are shaking the flask only, you should see the characteristics previously described. Also, I'd experiment with a gravity reading, the starter should finish below 1.010.

If you are brewing 5 gallons of 1.048 you'll need something north of 170 billion cells. I let yeastcalc do all my heavy lifting in determining starter size.

One thing you can be sure of, the yeast really don't care about your brew schedule.

 

Starters often do not have a good krausen. You will need to look for other evidence of activity. Does the wort smell like it has started to ferment? You could sterilize your hydrometer and go ahead and do as gravity reading anyways, then repour it into the flask.

 

Easiest way to tell if the starter did its thing while you weren't looking: taste the wort.

 

This is probably the problem. Adjusted for time you have almost 300 billion cells. Pitching that much in a 0.5L starter will give you no growth because you exceed the max innoculation rate (number of cells/ml of wort). If you had pitched 1/10 of your yeast cake into a 0.5L starter you would have doubled the number of cells. The other approach if you pitch the entire yeast cake is to make a huge starter (2+ liters) so all the yeast get a bigger portion of the wort.

Your goal is to get the yeast active, not necessarily add to the number. What you did is like throwing a pork chop to a starving pack of dogs . . . no single mutt gets much benefit. But give one mongrel a fresh chop or invite the whole pack into a huge buffet and they all gain weight.

Adding wort should (may?) give enough sugar for the little fellows to wake up. It looks like you need to be above 2 liters . . . that should get the yeast in action, although you probably will have to reduce the amount you pitch. Check out yeastcalc's calculator, it seems a little more user friendly when it comes to starters.

I have done exactly this resulting in complete fermentation. No problem mixing yeasts if they have compatible fermentation profiles, ideally you get the benefits from each strain. If the Burton is ready to start your primary will certainly drive the innoculation rate into the correct range. But be aware you may be overpitching if you use it all.

My thoughts are to get the starter active with more wort and use yeastcalc as a guide to see what you have. Remember, all of these growth rates are non-linear. So a 1L starter doesn't yield twice as much as 0.5L or half of a 2L. Yeast . . . we have to play by their rules.

 

It appears your yeast have come to life, at least you have an idea they are getting ready to play.

But it's still possible they are not ready to be pitched. This is a pretty long read, but it will address many of your concerns: http://www.mrmalty.com/starter_faq.php

This addresses a starter too small: it is likely the yeast will not build their reserves in a small starter. Remember, part of the reason to use a starter is to increase yeast health and to accomplish this there are some limits on the innoculation rate. The suggestion is to use a minimum size of 1L for 100 billion yeast. In your case I estimate your original yeast cake of ~500 billion cells. Adjusted for the two months gives you around 300 billion cells (these estimates are rough, but it is a starting point). I would recommend taking a portion of this (1/3'ish) and using yeastcalc to determine the starter size. In this case it would tell you a 1L starter would yield 190 billion cells. Most important is at this starter size the innoculation rate is low enough to get cell growth and to build yeast health.

We think in terms of "double the grain to double the brew", but the yeasties grow at different rates depending on how they are fed. I would rely on a good calculator (yeastcalc or brewersfriend) to figure out my starter size.

 

Basically, yeah. There should be an obvious difference in sweetness.

 

My advice would be none. I've never understood the idea some people have that there's some benefit to 'waking up' the yeast with a small amout of sugar. Basically, it would take the yeast through an adaptation phase that neither resembles the ultimate fermentation conditions nor increases the cell count significantly.