A couple Yeast Starter questions

I should first provide the caveat that while I make yeast starters, I personally do not use the Brewers Friend calculator. OK, with that out of the way:

“Is there a general size for a starter?” It would appear that the default value in the Brewers Friend tool is 2 liters. FWIW I brewed a batch yesterday and I chose to make a 2 liter starter (with intermittent shaking). But I have made smaller starters in the past tailored to each specific batch (e.g., I prefer smaller starters for some of my Belgian Ales to encourage development of esters in those beers). If you want, make a 2 liter starter for your batch. And I choose to use 2 litters of water and then add 200 grams of DME for my starters.

“It is also asking for the Gravity. What do I use for that? The starting gravity from my recipe?” The answer here is the starting gravity for your batch of beer. The reason is that for higher gravity beers you need to pitch more yeast cells.

Cheers!

 

You adjust the size of your starter to yield the number of yeast cells needed. I.E., in Brewers Friend step one has your volume, OG, pitch rate, and date of yeast. This tells you how many cells are needed...in your case you need an additional 108 billion cells. Now move to step two and adjust the volume of starter and aeration method that yields your desired number. It will display in red if you pick too low and green when at or above desired cells.

So don't be hypnotized to 2L, or 1L. The correct size may be something like 1.7 to give the desired results. They're are some inaccuracies inherent in this model but it's a pretty decent starting point.

Suggest you check out yeastalculator.com ... I find this a little easier to use than BF and you get a little more help along the way. It's more efficient not to over/under pitch your starter and this calculator gives you some more clues. The ideal inoculation rate in a starter is 50-125 million cells per milliliter of starter wort (this is from White/Zainasheff). If you experiment around with this you'll find that 1L + 1L ≠ 2L. That's because the yeast growth rate will vary depending on inoculation rate. In yeastcalc it clearly displays the inoc rate in step 2. Here's where you want to adjust the starter size for the perfect starter. If your yeast is really old it's possible you'll need a two step starter (move down to step 3). When I've harvested dregs from a bottle I've done 4 step starters to reach the 200B range. It sounds tedious but the calculator does all the work. Just play around with volume size (and aeration method) while keeping the inoc rate in range until you get the results needed. A multi-step starter can be computed in just a few minutes with no heavy lifting on your part. Yeastcalc even computes the DME required for each step.

A big advantage I find with these calcs is I almost always make an excess of cells for each batch. If I need 200B it's almost no trouble to have the starter yield 300B, then decant ⅓ of the batch and save for the next brew day. Much easier than washing yeast from the trub.

A couple of caveats: There is no universal agreed upon yeast pitch rate. Most of the calcs have a 0.75 million cells/ml wort/degrees-Plato setting and that's a good starting point for ales. But expect others to say that's too much or too little.

Most of these calcs default to 100B cells per packet for liquid yeast and assume a 21% decrease per month when computing viability. In practice you'll find different figures from different yeast companies. Omega advertises 150B in their packets. White Labs says their Pure Pitch will have 1.8-2.8B cells per ml of slurry and that their yeast doesn't degrade at that 21% rate but much slower. I'm sure there are other mfg's with results all over the board.

Yeast producers seem to intentionally want to keep homebrewers in the dark on cells/packet and preferred pitch rates. Almost all encourage brewers to accept that one packet is good for one batch, or pitch another packet if you think it's really necessary. You can see where they have some obvious bias.

To keep this from being too wordy here's two links that do a better than average job on explaining pitch rates and managing your starters:
https://www.mrmalty.com/starter_faq.php
https://www.mrmalty.com/pitching.php

 

Depends on what flavor profile you are seeking from the resulting beer.

For example, some yeast strains will ferment cleaner (i.e., produce less esters) if you over-pitch.

Also, over-pitching may result in increased levels of fusel oils (higher alcohols).

Cheers!

 

Yes. From Yeast: Over pitching can result in low attenuation, high levels of diacetyl/acetaldehyde, low or unexpected esters, yeast autolysis flavors and poor head retention. If you have to pick between over or under pitching then over pitching is a little more forgiving.

 

Ideally you want the starter to be complete, chilled, and ready to decant/pitch just as your wort cools to pitching temp. But there's no need to cut it that close as having it ready a day early is no problem.

If your yeast is relatively fresh it should "start" in a couple of hours, then reach high krausen in less than 12 hours, then crash out in another 12 hours. But different strains like to surprise you sometimes (I'm talking about you, Monsieur Belgian). I like to chill overnight so it's ready the next morning but when pressed will start the chill process first thing in the AM for an afternoon pitch.

Don't lose sleep over this...starting the starter 36 - 48 hours before you're ready to pitch will work. Even with this you could postpone brewday by another day and it'd still be fine.

Something that hasn't been brought up is one of the main reasons to use a starter is to ensure the little yeast buggers are really viable and ready for action. That's probably as important as the actual cell count.

 

In the links I posted above they talk about pitching the entire starter or chiling/decanting the yeast solids. IMO it's a big mistake to pitch the entire starter.

If you pitch the entire starter you are making a serious sacrifice to your original recipe. Say you have a 1.5L starter pitched into a 5 gal batch . . . that's about 8% of your total quantity which is highly oxidized. Do you want to drink that? Also your bitterness is off by the same amount, plus your overall malt profile is changed. Still want that?

It's little effort to chill the starter the night before in the fridge When you wake up most of the yeast will have floc'ed to the bottom of the flask.and the liquid will start to be clear. Ideally you want to pitch the yeast when its temp is slightly below your wort temp. Taking the flask out of the fridge about an hour before your wort is ready works well. If you're ferm'ing at 64 then pitch your yeast when it's 55-60 . . . even up to 64 is okay. You can guess what happens when you pitch 80° yeast into 64° wort.

Carefully tilt your flask to pour off the liquid using care not to disturb the solids on the bottom. Do this in one continuous motion which will be tricky the first time. It's like the first time you had sex . . . there will be some moments where you don't know what's going to happen next. But (like sex) you get better with practice. A small of amount of liquid will stubbornly refuse to be decanted, accept this. Sometimes the solids "stick" to the bottom . . . resolve this by adding some of the fresh wort to your flask and swirling.

If you want to keep some of the yeast for a future brewday simply split your batches the night before. Example: you need 200B but have created 250B. Pour a little less than ¼ of your starter into another container and let both chill in the fridge the night before brewing. You now have 50'ish billion cells extra. After sparging is complete run off an extra half liter or so of extra wort, boil, cool and create a new starter with your extra yeast. Your final runnings wort will be somewhere around 1.020 - 1.030 which works for a starter. Like a circus, you have the fermenter staring in the main show and the stir plate doing its thing on the side. Let it rip for a day or two, then chill and store for the next brewday . . . the Joy of Homebrewing.

 

No sir, I do not.

Nope. I recall a discussion from a few years ago, where a proponent of going ahead and pitching starter "beer" along with the yeast, after much back and forth, claimed that they adjust their recipes to account for these volumetrics. Sure they do. I will not name them. Certainly not three times while looking in a mirror.

 

So . . . what did you end up doing?

 

64-68F is fine. 68F would be faster than 64F. Decanting is always a good idea from a flavor/aroma perspective, mainly because of oxidation, regardless of temperature. (And 68F isn't going to cause excess esters.)