March 2012

The starter was bubbling away, so I went ahead with the brew. It gave rise to an interesting chemistry/physics problem.
The Grain Tea:
Just over 2gal of cold tap water was added to the brew kettle and placed on a large stove burner. One pound of crushed Briess Caramel 40 specialty grain was put in a muslin bag and placed in the brew kettle to steep while the water was brought to temperature. At 180ºF, the grain bag was removed and the grain tea continued to heat to a boil.
The Malt Extract:
When the grain tea boiled, the kettle was removed from the burner and 9.15 pounds of Gold malt extract was added to the grain tea. Hot grain tea was used to rinse out the malt extract jugs. The mixture was stirred thoroughly to completely dissolve the malt extract before the kettle was returned to the burner to boil.
The Hops:
When the wort reached a boil, 1oz of Centennial pellet hops were added and the wort was boiled for 35 minutes. An additional 1oz of Centennial pellet hops was added and the wort boiled 20 more minutes. A final 2oz of Centennial pellet hops was added and the burner turned off; the residual heat in the cooktop maintained a boil for a few more minutes.
Wort Cooling:
The brew kettle was brought outside and put in a snowbank to cool. This seemed like an excellent way to cool the wort, but it seemed to take more time than I would have expected. As I thought to myself, “Damn it, why doesn’t this cool faster?!?!”, I realized that I am fully capable of answering that exact question. I have about 2.5gal of liquid at right around 100ºC that I want to cool to 25ºC. If we assume that the solution has a density and heat capacity a little higher than pure water, the amount of heat that must be removed from the wort is:

(2.5gal)(3.78L/gal)(1000mL/L)(1.1g/mL) = 10395g of wort
(4.2J/g•ºC)(10395g)(75ºC)(0.001kJ/J) = 3274kJ

That’s quite a bit of heat. If I’m trying to remove that heat by phase-change of snow to liquid water, we can assume that the ΔHfusion of snow is the same as “regular” ice, although all the air pockets in the snow will insulate it and potentially snow things down. “Slow down” is a kinetics problem, right now I’m looking at thermodynamics. So to soak up that much heat, we would need to melt:

(3274000J) / (335J/g) = 9770g of ice must melt

There’s been a serious melt going on in Moorhead the last day or two, so the snow is quite wet and (relatively) dense, let’s say 0.5g/mL, so the amount of snow needed to pull 3274kJ of heat out of the wort is:

(9770g) / {(0.5g/mL)(1000mL/L)} = 19.5L

That’s right around 5 GALLONS of snow. On the kinetic side, the heat transfer is slowed by any gas pockets or spaces between the hot brew kettle and the snow crystals, so what I really should have done is take a large container (garbage can?) and put a bit of snow/water slurry in it, then put the brew kettle in, then packed a bunch of additional snow in around the brew kettle. As it was, it too over 30 minutes for the wort to cool, and that’s a little longer than I would have liked.
Final Wort:
The cooled, concentrated wort was strained into 2gal of cold tap water in a 5-gal ale bucket to remove most of the hops and to aerate the wort. The wort was drained through the ale bucket’s spigot into a 6-gal glass carboy, again, aerating the wort. The yeast starter was added and water was added to about 5.5gal total volume, the carboy was sealed with a 1-hole rubber stopper connected to a tube for initial fermentation, and the end of the tube was submerged in bleached water to serve as an air lock. This was all completed by approximately 2:30pm on March 11th. By ~8pm, a nice small-bubbled foam had developed on the wort with a bubble rate of under 2 seconds per bubble.

I have both a 5-gal and a 6-gal glass carboy. I prefer to use the 6-gal for primary because it: a) lets me start with a little over 5gal of wort so I can rack a full 5gal to the secondary; b) has a little more room for the large foam head and rapid out-gassing of the primary ferment. Extra headspace can be a contamination risk, but because the primary ferment is so rigorous there is a very positive “out” bias in the primary fermenter. When I rack to the 5-gal carboy for the secondary ferment, I like to minimize the headspace, which is another argument for the larger primary wort volume.

Primary ferment should take about a week. I plan to move the carboy into my spare bedroom in the morning, it is immaculately dark in that room, and it’s a few degrees cooler in that room (58-60ºF). The cooler temperature will slow fermentation, but it shouldn’t slow it down too much.

Once again, I forgot to check the initial gravity of the wort. Arg, double arg, and damn. I could pull a sample right now, but it’s probably not the most crucial thing to know. I’ll try to remember to test a sample when I rack to the secondary, although I’m not sure what that will really tell me. Oh well, in about 6 weeks I should be able to report a delicious and hoppy experience. Then maybe I’ll try that British Bitter…

After a few years break, I’m brewing another beer. I decided to go with a kit from Northern Brewer ( ), and after looking over a few of their options I picked their Dead Ringer IPA ( ). I like a nice hoppy IPA and the Dead Ringer kit has 5 ounces of Centennial hops. Yikes. I chose the Wyeast 1056 American Ale yeast option ( ). It’s a direct pitchable yeast, in a “smack pack”; I had never used a direct pitch yeast before, more on that later.

Because the Dead Ringer is a little on the higher gravity side, a starter is recommended, even with the direct pitchable yeast. Personally, I always make up a starter. I don’t think I’ve ever gotten a bad sample of yeast, but if I did get a pack of dead yeast I’d rather find out about it when the starter doesn’t work than with the full 5-gallon batch. I planned to brew on Sunday, so first thing Saturday morning I got up to put my starter together.

The Starter:

900mL of water and a little over ½ cup of light dry malt extract were combined and set to boil. The mixture was whisked to combine and dissolve the DME. I squeezed the yeast pack around, trying to find the inner nutrient activator pack to pop and begin to activate the yeast. Because I had never used a direct pitchable yeast pack before, I didn’t really know what I was feeling for and as I pinched and poked and prodded, I eventually popped a hole in the outer pack and shot a squirt of yeast across my countertop. Damn. Of the “100 billion yeast cells” advertised to be in the pack, I probably just shot 5+ billion of them all over the countertop. As I was wiping up the yeast squirt, I stopped paying attention to the starter wort I was heating up on the stove and all of a sudden with a steaming “woosh!” it boiled over. For those unfamiliar with brewing, malt extract and the wort made from it is a very sugary, sticky, sweet mixture, so I had just slopped boiling sugar water all over my very hot glass stovetop. I suppose it’s good that I have a sealed top range, otherwise it would have been a much uglier, stickier mess. So I cleaned everything up and re-started the starter…

The Starter, Second Attempt:

I dumped the rest of the yeast pack into a measuring cup. The inner nutrient pack was open, so I had hopes that the yeast was still good and ready to ferment. 1L of water was warmed to just short of boiling and 2/3 cup of DME was added and whisked in to dissolve. {I used a little more DME this time because I was almost out of DME so I used all the remaining.} I carefully brought this starter wort to a low boil and boiled/simmered for 10 minutes. During this boil, I noticed a the yeast starting to bubble, so it should be good. The starter wort was cooled (in a snow bank) to a little over room temperature, and it was poured into a cleaned and sterilized 1.75L New Amsterdam gin bottle. The starter wort was agitated fairly vigorously to aerate it well, and the yeast was pitched (~8:15am, 2012/03/10). The bottle was sealed with an air lock. I like to use vodka in my air locks, it’s sterile, doesn’t support biological activity, and if negative pressure builds up and some of the vodka is sucked into the fermenting wort, it won’t really affect anything.

After a few minutes, I was some bubbles forming, so it looks like the yeast was OK and the starter will re-grow some of those billions of cells I spilled. I left the starter to do its magic and went in to work for the day. If it looks good by this afternoon, I’ll go ahead with the brew tomorrow; if not, I’ll pick up some new yeast and wait. I’ve usually used dry yeast packets in the past, they’re cheaper and more stable. My first experience with a pitchable activator pack has left me thoroughly unimpressed and I won’t be using it again. I’ve used White Labs yeast before, it comes in very cool tubes, and I’ve had good luck with it. Both the Wyeast and the White Labs yeasts are $6-7 per pitch, dry yeasts are just a few dollars per pack (Munton’s is only $1.25, ), so I might go back to the dry yeasts for future batches.

This Dead Ringer IPA will take 6+ weeks to be drinkable, I should have picked up a quicker one, I’d kind of like to try Northern Brewer’s British Bitter ( ).  More later…

Over the course of my career, I have used a variety of technologies to aid in my teaching of chemistry. I started with a relatively simple email listserv. It was effective, but was more of a way to make announcements to my classes than anything else. It also seemed that many students didn’t understand what a listserv was; I told them all to sign up for it on the first day of class, but they would often wait (and wait and wait and wait) and then a day or two before an exam they would sign up and ask me how to get all the old messages. Sorry kiddoes, that’s not the way a listserv works.

The next step was a blog. This had the advantage of all the previous posts being available, but I still used it as more of a message source.

A few months ago, I was bitten by the Twitter bug, and I have been using it for more-or-less professional contacts and posts. After giving it some thought, I decided to try and incorporate Twitter into my class-related social media. For Spring 2012, I have been posting lecture recaps to Twitter using #GenChem2012. These are not comprehensive lectures, that would be challenging if not impossible given the format of Twitter, but rather the high points of the class. In addition to these tweets, I have been making more detailed posts to the class blog. Philosophically, I have mixed feelings about these blog posts; I don’t like posting complete lecture notes because it may encourage students to skip class, but for the students who do attend class, these blog posts could be very useful additions to their own notes from class. Another reason for posting more comprehensive lecture notes/summaries is that I have been toying with the idea of writing a General Chemistry textbook, and these blog posts could provide a bit of a framework for that future project.

At this point, the social media experiment seems to be going well, although I have not yet gathered real data to support this claim. I intend to attempt to quantify the impact of this effort, but it seems like the kind of impact that will be difficult to nail down.