SeanTerrill.com

Two-Stage Starter Calculations

webmaster — Mon, 08 Mar 2010 05:04:45 +0000

There are many situations in which a homebrewer might need to propagate yeast using more than one step-up – for example, building up from a bottle of commercial beer, or reviving a smack pack that’s several months old. And while I love Mr. Malty’s Pitching Rate Calculator™, doing two-stage starters with it can be frustrating.

One simple alternative is to use Wyeast’s Pitch Rate and Growth Calculator. It does have some limitations: it works only in gallons, doesn’t feature a viability calculator (although viability can be input manually as partial smack packs), gives results in fairly useless intermediate units (millions/mL) as opposed to cell count or pitching rate (millions/mL-°P), and does not allow for decanting the starter. So in my opinion the best option is to trick the MrMalty calculator into doing it. Here’s how:

Set your production date or viability, then play with the gravity and/or volume fields until the output matches the volume of your first stage.
Note the number of cells that result.
Turn off the automatic viability calculation and enter that number for the viability.
Enter your actual gravity and volume, and the calculator will tell you the volume of the second stage.
Verify that the volumes are realistic and adjust the first-stage volume if needed. Ideally, you want to at least double the volume at each step.

For example, let’s say I want to build a six-month-old pack of Wyeast 2206 into enough yeast for a 21 L (5.5 gallon) batch of 20°P (1.084) doppelbock. The required cell count is:

(21 L)•(20°P)•(1.5 billion/L-°P) = 630 billion. And the pack’s viability is:

0.75^6 = 0.178, or about 18 billion cells.

So I need to increase the cell count by about a factor of 35. This is clearly not possible with a single starter. So I’ll start with a 3 L first stage. Using “intermittent shaking” with a viability of 18%, volume of 5.5 gallons, and gravity of 1.022, the calculator predicts 174 billion cells total. I then set the viability to 174% and the gravity to 1.084, and the calculator tells me that the second stage will need to have a volume of about 7.5 L. Clearly this is one of those situations in which I should be brewing a 2-gallon batch of light lager as a “starter”.

Yeast Starters Three-dux

webmaster — Thu, 04 Mar 2010 21:46:38 +0000

I’ve finished the last starter needed to round out my aeration experiments. Once again, the main post has been updated with the full data set and some additional thoughts.

Things I Hate #56: Valet Carry-On Baggage

webmaster — Thu, 04 Mar 2010 19:51:58 +0000

Three of the four words on this tag are lies.

On my recent trip to New Orleans, given that I was only traveling for four days, and not a women, I only needed to pack one bag. I elected to take only a carry-on – an easy decision given that checking luggage costs one-fourth as much as the actual ticket. The only problem was that everyone else came to the same conclusion, and so I was forced (yes, literally) to check my bag in the jetway, while almost everyone else carried one of their two bags onto the plane. They didn’t care about that argument; next time I’ll know to bring a second, decoy bag.

The problem basically is this: even with my tax dollars, the airlines are apparently unable to turn a profit. So they decided to start charging people to check bags. Consequently, everyone stopped checking bags. So now there is no longer enough room on the plane for all the carry-on luggage. Especially when the plane is full – or, technically, more than full. (Sidebar: How hard is it to count the fucking seats, and only sell that many tickets?) Of course, two of my four flights were actually not full; once we all got seated the overhead compartments were totally empty. They didn’t care about that argument either. From which I’m forced to conclude that this policy has nothing to do with the bags themselves.

The simple solution would be to return to the status quo and allow people to check bags for free. But that doesn’t help keep your company from hemorrhaging money, so the airlines decided to go a different way. Now they make passengers wait in a freezing jetway, in the hopes that some will just pony up the cash to avoid the hassle. I call that a shakedown. The airline calls it “valet carry-on service”.

This is not a “carry-on” bag. I wanted it to be a carry-on bag, but you wouldn’t let me. It’s a checked bag.
This is not “valet” service. A valet is someone who parks your car for you, not someone who walks up and takes your car away before you can park it yourself. Actually, there is an automotive analogy for that situation, but it isn’t valet service. It’s carjacking.

Fuck you, “valet” “carry-on” baggage.

Yeast Experiment Update

webmaster — Wed, 03 Mar 2010 23:45:13 +0000

I was able to brew the test beers for the Yeast Pitching Rate Experiment today. Some notes on the brew session can be found on the main experimental page.

85% efficiency on a 1.059 beer, though… I do love my Barley Crusher.

Why Do Bad Things Happen to Good Movies?

webmaster — Tue, 02 Mar 2010 03:52:06 +0000

Dear Hollywood,

We have a lot of history together – not all of it good, but we’ve had some laughs over the years. Lately, though, it’s become apparent to me that we’re moving in different directions. I think it would be best if we parted ways now, rather than try to carry on in this sham of a relationship. Please don’t call or write me.

P.S. This isn’t a race thing.

Crescent Crawl

webmaster — Mon, 22 Feb 2010 00:53:09 +0000

Name: NOLA
Date: Feb 21, 2010 6:01 pm
Distance: 3.86 miles
Elapsed Time: 40:08.1
Avg Speed: 5.8 mph
Max Speed: 12.0 mph
Avg Pace: 10′ 24″ per mile
Min Altitude: 33 ft
Max Altitude: 108 ft

Click on this link to display the track in Google Maps. This link will be valid until Mar 23, 2010 5:47 PM PDT.

Rock Us, Bacchus

webmaster — Fri, 19 Feb 2010 18:57:17 +0000

Je vais voyager en Nouvelle-Orléans de ce soir à mercredi. Laissez les bons temps rouler!

Yeast Pitching Rate Experiment

webmaster — Fri, 19 Feb 2010 04:19:50 +0000

Most homebrewers, once they get seriously involved in the hobby, will make starters for their beers. While the commercial yeast products are advertised as being “pitchable”, their cells counts don’t allow brewers to inoculate a 5-gallon batch of ale at the industry standard rate of about 0.75 billion/L-°P. And the true cell counts may be substantially lower.

This has always puzzled me. Wouldn’t it be in Wyeast and White Labs’ interests to advise pitching two – or more – of their products? Regardless, are they correct in their recommendations, or should homebrewers pitch the same amount of yeast as professionals? What are the effects of varying the pitching rate, and how noticeable are they?

Based on a rather heated discussion in the Northern Brewer forums, there is both a great deal of interest in these questions, and no consensus on the answers. A recent collaboration between Basic Brewing Radio and BYO attempted to address these issues, but was limited in both the number of participants, and the applicability of their results (since each brewed different beers). To get around these logistical shortcomings, I propose the standard engineering solution: let’s throw money at the problem.

Briefly, what I plan to do is brew a batch of beer (a tentative recipe is below), split it into two fermenters, and pitch one at the standard rate, and the other at the rate that would result from pitching a vial or pouch of commercial yeast (about 0.3 billion/L-°P). I’ll then ship three samples, identified only as A, B, and C, to as many tasters as possible. Each can then do a blind triangle test, fill out a standard survey form (also below), and return it. Ideally there will be enough respondents to be able to perform statistical analyses on the data.

If you want to get involved, it isn’t too late. Either sign up via the NB forum topic, or Contact Me directly.

Update: 03 March 2010

The test beers were brewed today. I began by building up the starters from 10 mL of slurry that was 52 days old (approx. 25 billion cells). The slurry was pitched into 500 mL of starter wort (~50B); after 24 hours this was split evenly between 400 mL (~50B) and 2.4 L (~125B) starters. These were allowed to ferment to completion, while being shaken as often as possible, then placed in a refrigerator 16 hours before pitching. All propagations were conducted in wort that was 8-9°P, with about two-thirds of the gravity coming from a mash of Castle Pilsen malt, supplemented with Briess Pilsen DME.

The actual brewing session was uneventful, although I underestimated the mash efficiency slightly. The wort was chilled to 17°C (63°F) and split between two 6.5 gallon plastic bucket fermenters. Each ended up with just over three gallons of 14.6°P (1.059) wort. They were aerated for 10 minutes with an aquarium pump and stone, then the decanted starters pitched and the fermenters placed in a room with a steady ambient temperature of 62°F.

The resulting pitching rates are 0.29 and 0.73 billion/L-°P, although the second significant digit is obviously not justified.

Downloads:
Caramel Camel Amber Ale (PDF) | Sensory Evaluation Form (PDF)

How I Spend My Time at Work

webmaster — Tue, 16 Feb 2010 00:36:01 +0000

I really don’t know what all the fuss is about graphic design. This was super easy and hardly looks like crap at all. (It’s also an awesome example of your tax dollars at work.)

This gag would work a lot better if it was an actual pizza.

Yeast Starters Redux

webmaster — Sat, 06 Feb 2010 19:04:17 +0000

As a quick follow-up to my starter aeration experiments, I made up a DME starter for comparison purposes. As would be expected, it produced substantially more yeast than the sugar starters. So if nothing else, don’t take the cell counts estimated in the original tests to be accurate for beer – something I probably should have emphasized. The original post has been updated with the new data.