Yeast Starter - How do I know its working?

If I make a yeast starter and am using a stir plate, is there any way I can tell how well the starter worked?

Right now, if I poured in a vial of dead yeast, I'm not sure I would know the difference. I've done a couple of starters so far and it looks like I have more yeast than I started with, but I can't tell for sure. I could measure the volume of the yeast after the starter but I don't want to do that for fear of contamination.

With a 1.2 liter starter and 1.036 OG starter wort, should I expect to see double the yeast? Triple?

They do smell like beer fermenting, so I assume something is working. I just don't know how well.

A yeast starter is just like a little mini brew. The yeast eat the available sugars, give off alcohol and CO2 as byproduct, and reproduce/replicate.

In the starter, you should notice some activity like the yeast colonies moving around/floating up and down, maybe some CO2 bubbles and the associated sulphur smell, the amount of sediment/yeast should increase, and the gravity of the solution should go down - All the same things that happen in a larger wort volume.

Activity in a starter really only means one thing and one thing only.

It doesn't matter one blip in your fermenter or your starter flask if the airlock bubbles or not (if you are using an airlock and not tinfoil if you are using tinfoil, you aren't getting bubbling anyway,) or if you see a krauzen.

In fact starter fermentation are some of the fastest or slowest but most importantly, the most boring fermentations out there. Usually it's done withing a few hours of yeast pitch...usually overnight when we are sleeping, and the starter looks like nothing ever happened...except for the little band at the bottom. Or it can take awhile...but either way there's often no "activity" whatsoever....

I usually run my stirplate for the first 24 hours, then shut it down, if you are spinning your starter it is really hard to get a krausen to form anyway, since it's all spinning, and there's often a head of foam on it from the movement.


All that really matters is that creamy band o yeast at the bottom.




This is a chilled sample so it's flocculated, but even with an unchilled sample you should see a band of yeast at the bottom. Here's an unchilled version



Same thing, a band.

As it is I've only ever seen two or three krausens actually on my starter (one blew off a bunch of krausen and knocked the tinfoil off the flask,) and the evidence of one on the flask at the "waterline" once. But I've never not had a starter take off.

Look for the yeast at the bottom, don't worry what it looks like on top.

If you have yeast on the bottom....that's all you really need.

If it looks anything like that, your are ready to either feed it again, or use it.

Yeast at the bottom doesn't mean it actually reproduced though. I think the op wants a more obvious sign that it worked. It is a bit hard to tell if it reproduced after a feeding, even after its chilled and dormant. One thing I notice is, if its a fresh vial, and has viable yeast, theres a ring of bubbles around the top while the stir plate is on. If you turn the stir plate off, you can see the co2 rising. On vials that were completely dead, I never noticed bubbles at all. I have an expired vial of 002 I just put on the stir plate an hour ago. In a couple of hours I should start to see some bubbles of co2 forming. If I don't, and a refractometer sample hasn't budged, i'll probably just toss it.

mikeysab said:

Yeast at the bottom doesn't mean it actually reproduced though.

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Yes it does, when the yeast finishes if it's not being whipped around on a stirplate, it tends to flocculate. And you see it.

Sorry, but I've never noticed co2 bubbles in any of my starters, on a stirplate or otherwise.

To me that's another one of those risky "signs of fermentation" that doesn't always happen to all brewers. And therefore is a lot less risky then looking for a band of sediment on the bottom of the vessel.

mikeysab said:

Yeast at the bottom doesn't mean it actually reproduced though. I think the op wants a more obvious sign that it worked. It is a bit hard to tell if it reproduced after a feeding, even after its chilled and dormant.

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Yes, that's what I'm looking for. Some (preferrably easy) way to tell that the goal was accomplished.

Right now I'm just blindly calculating the yeast starter size (using Mr. Malty) and assuming the yeast viability based on the date. For all I know the vendor I bought it from could have left it on the dash of their car for a week... or more realistically UPS could have left the package in the top of a package truck all weekend out in the sun. The cold pack on this last vial wasn't a bit cold when I got it.

If I took a gravity reading of the wort after 36 hours on the stir plate, and it is around 1.012, give or take, could I assume things went pretty well?

Revvy said:

In fact starter fermentation are some of the fastest or slowest but most importantly, the most boring fermentations out there.

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I agree with you. And sometimes, the most vigorous: Occasionally I get one that goes a bit crazy, like this:



MC

Revvy said:

Yes it does, when the yeast finishes if it's not being whipped around on a stirplate, it tends to flocculate. And you see it.

Sorry, but I've never noticed co2 bubbles in any of my starters, on a stirplate or otherwise.

To me that's another one of those risky "signs of fermentation" that doesn't always happen to all brewers. And therefore is a lot less risky then looking for a band of sediment on the bottom of the vessel.

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Well, if you take a vial of yeast and pour it into a liquid and let it sit on the counter, you'll notice a band of yeast on the bottom. Does that mean it reproduced? Sure, if you make a starter, then after awhile, it'll start to look actiive, then fflocc out when the food is gone,but I could pour yeast into water and get a band of yeast on the bottom.

I use a 2 qt mason jar for starters. If I make a one liter starter, let it finish, then cold crash it, I wouldn't be able to tell if it worked by looking at the yeast band on the botttom.

You could always use a refractometer or hydrometer to tell if it did anything.

mikeysab said:

I use a 2 qt mason jar for starters. If I make a one liter starter, let it finish, then cold crash it, I wouldn't be able to tell if it worked by looking at the yeast band on the botttom.

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That's what I was just thinking (because I'm preparing to do a starter with washed/harvested yeast). I have a large band of yeast in the mason jar, so when I do the starter, even if that yeast is dead and doesn't do anything, wouldn't it still all eventually settle back to the bottom?

Everything will eventually settle to the bottom. If its healthy yeast, it'll eat the sugar, float around, then settle. If its all dead yeast, it'll just settle out. If its on a stir plate, its hard to tell if its doing anything. Like Revvy said, looking for signs of fermentation isn't reliable. You could see no signs, but that doesn't mean it didn't work

I generally look for a change in color and apparent consistency. When I first pitch the yeast, the color of the wort is a sort of thin, translucent light brown, but after 24 hours on the stir plate, which is when I generally stop the process, the color has typically changed to a thicker, creamy brown. That's my clue that major reproduction has taken place.

I love seeing that brown wort turn into creamy khaki.

Well, I've noticed something this time around since I've been paying more attention. When I put the starter on the stir plate I could see little tiny specks of yeast flying around in there. Now, about 24 hours later, I can see much larger chunks swirling about. Looks like each little speck I saw earlier probably tripled its size or better.

Next time I make a starter I'll try to remember to take good pics at various intervals and post them here. Might even do a time lapse video.

I just recently started making starters. And they are still a bit mysterious to me. Some foam up, and some show nearly nothing. I wonder how to choose the ideal pitch time?

The pic of the 1762 and 1388 are at about 24 hours with every other factor identical, pitched then.

The single pic is a 1214, said to be a slow yeast, showed zero signs till 40 hours, pitched at 50.

The 3787(not shown) showed little in the flask yet was the only one so active in primary as to need a blow-off hose.

Not sure how much settled yeast at bottom is good? 1/8? 1/4? More? Using 100Gram DME per liter of RO water.

I always prefer to pitch too late than too early. If your yeast reached krausen too early, you can always let it sit, drain some of the liquid (leaving the yeast cake behind), and add additional fresh cooled wort.

That being said, I usually start my starters 4-6 days ahead of brewing, mostly because my yeast bank is fairly old.

JP

Because this is posted in the newbie forum I have to ask. What is the benefit of making a yeast starter?

jturman35 said:

Because this is posted in the newbie forum I have to ask. What is the benefit of making a yeast starter?

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Multi-faceted. A starter:

- Ensures your yeast is viable. In the event you're using yeast that may not work, you're better off working with a few hundred milliliters of a starter, instead of 5 gal of a full batch. Mainly important if it's old or you suspect it's been handled improperly.

- Builds yeast cell count and (i think) health. Underpitching (amount) or pitching unhealthy yeast could result in unexpected flavors.

- In addition to higher cell count, a starter allows the fermentation to hit the ground running instead of needing to gain momentum. The quicker your fermentation starts, the less opportunity unwanted bugs (infections) have to gain foothold and messing up your batch.