SeanTerrill.com » Brewing

Double Grain-Brew

webmaster — Fri, 27 Jan 2012 05:12:11 +0000

As I mentioned recently, I’ve been making a conscious effort to branch out and brew some less traditional beers lately. This pair of porters is a good example. The base recipe is the same for both, but one has a substantial portion (30%) of the grist replaced with Briess Cherrywood Smoked Malt, and the other was aged on chipotle peppers post-fermentation.

For starters, a double brew session without a shared mash and/or boil makes for a long day. I mashed in the first beer right at sunrise (9:30 AM) and wasn’t finished cleaning until after 6 PM. So if I try that again it will be on a much warmer day.

I bet chipotle vodka isn't half bad.

Anyway, on to the beers. They’re both good. Unfortunately, the cherrywood malt is quite a bit milder than its beechwood cousin, so while the balance was superb to begin with, after two months it’s fallen off to the point that it’s barely noticeable. In a beer with as much going on as this, I think a better guideline might be around 50% with a short aging period to allow for mellowing of the phenols, or 30-40% in a beer that’s destined to be drunk more quickly. I’m going to be brewing a lager using my remaining store of this malt, and it will be interesting to see how it holds up in a more straightforward grain bill.

I’m a bit happier with the chipotle porter, although it too has become a bit less balanced with age. In this case, the roasted malt character of the base beer has fallen off, increasing the perceived piquancy over time. On that subject, I should probably point out that I have a capsaicin tolerance higher than most, and also have the smoked porter available for blending. While 2.0 oz of peppers worked well for me, you might want to use less. On the other hand, the Scoville rating of chipotles varies widely, so comparisons from one lot to the next are more or less irrelevant. As when cooking with chiles, experience should be your guide.

The peppers should be naturally abiotic, and I imagine that the smoking only helps in that regard. I didn’t want to take any chances, so I coarsely chopped the chipotles and steeped them in just enough vodka to cover them. After a few days I dumped the whole mess into the fermenter, just about the time fermentation was winding down, and left them in contact with the beer for a week. In other words, I “dry-peppered” the beer. I don’t have a baseline for comparison, but the finished beer does have a wonderful chipotle aroma, so I’ll probably stick with this technique going forward.

Smoke in the Porter recipe (PDF)
Fire on the Side recipe (PDF)

Refractometer Calculator

webmaster — Sat, 07 Jan 2012 01:33:09 +0000

This is something I’ve been meaning to do for a long time, but kept finding excuses to put off. It uses the simplified cubic polynomial derived in Refractometer FG Results. Please visit that post for more information.

Fall Classic Tasting Notes

webmaster — Thu, 08 Dec 2011 23:52:02 +0000

Now that the holiday season is in full swing, I’m finally getting around to posting some tasting notes for the Fall Classic.

The visual appearance is really great. Deep amber with brilliant clarity, despite all the pumpkin in the mash, and an off-white head with excellent retention and lacing. The aroma is predominately of the spices, with some nice bready and toasty notes as well, although there is a hint of a green or vegetal character. I’d had the beer several times before I noticed it, but now that I know it’s there it’s frustrating. If I had to guess, I’d say you could reduce the amount of pumpkin used to eliminate the aroma impact.

The flavor is nearly perfect, if I do say so myself. The initial impression is of rich malt that manages not to be sweet, not unlike a good doppelbock. The home-toasted malt is clearly adding quite a bit of flavor. Through the middle of the palate and into the aftertaste, the spices really come into their own. The finish has a dry, graham-cracker crispness and just a hint of alcohol heat, and the spices linger, which makes each sip a lengthy and satisfying experience.

I think the overall quantity of spices is just right, although you might have to adjust the ratios to suit your own preferences. If anything, the malt complexity may be a bit overdone. I have no trouble finishing a couple pints, but that’s about it. Which is OK, because this beer is pretty much a meal in a glass. The only foods it would really pair well with would be pumpkin pie and other spiced desserts.

Does it taste like a piece of pumpkin pie? Not really. There’s next to no sugar in it, after all. Is it the best pumpkin-spice beer I’ve ever had? Yes, and by a pretty wide margin. I’ve tried every commercial example I could find (you know, for research) and the one that comes closest is Elysian Night Owl.

A More Accurate Approach to Draft System Balancing

webmaster — Fri, 11 Nov 2011 17:23:16 +0000

Balancing a draft system is one of those things that should be easy, but inevitably ends up requiring some trial and error. The basic principle seems sound: beverage tubing supplies some characteristic resistance per unit length (2-3 psi/ft for 3/16″ ID tubing), and all one needs to do is divide that into the desired serving pressure to get the length of tubing required. Under typical serving conditions (38°F and 10 psig, yielding 2.4 vol CO₂), this seems to provide acceptable results, with 5 ft of 3/16″ beverage tubing giving a balanced pour. For lower- or higher-pressure pouring, however, this approach breaks down. Which is frustrating; after all, the line resistance should be constant.

In order to take a closer look at what’s going on, we first need to calculate the pressure drop per unit length of tubing. I’m going to assume a flow rate of 40 mL/s. That’s a 12 second pour, which I think is a pretty reasonable average. Given the flow rate, calculating the Reynolds number is trivial:

Re = QD_H/νA = (40e-6 m³/s)(4.8e-3 m)/(1e-6 m²/s)(π(2.4e-3 m)²) ≅ 11,000.

We can also work out the velocity, v = Q/A = 2.2 m/s. For a typical home draft system, the beer is covering the distance from the keg to the glass in less than a second.

Anyway, that’s well over the threshold (Re > 2300) for turbulence, so we can assume fully developed turbulent flow throughout the tubing. Solving for pressure drop using a Moody chart gives a friction factor, f ≅ 0.031, so:

ΔP/l = ½fρv²/d = 0.5*0.031(1015 kg/m³)(2.2 m/s)²/(4.8e-3 m) ≅ 1.6 x 10⁴ Pa/m, or 0.71 psi/ft.

So the pressure drop due to the tubing itself turns out to be much less than the typical assumption. For our prototypical “10 psi, 5 ft” system to be balanced, the other hardware in the system – the keg tubing, poppet, post, and disconnect, plus the faucet or tap – must be providing the additional 6.5 psi of pressure drop. Looking at the problem under those conditions, things suddenly make a lot more sense.

Let’s take the example of a highly-carbonated beer that we want to serve at 38°F and 3.2 vol CO₂. That will require a pressure of about 18.5 psig. With the other hardware dropping 6.5 psi, the length of tubing required is (18.5 – 6.5 psi)/(0.71 psi/ft) ≅ 17 ft. Had we assumed a drop of 2 psi/ft, there would be only 9 ft of tubing in the system, and we would be pouring nothing but foam.

Simple Sugars and Specific Gravity

webmaster — Thu, 27 Oct 2011 16:46:25 +0000

A pound of sugar per five gallons of beer will add nine points to the original gravity and reduce the final gravity by two points.

We’ve all heard it. I’m ashamed to say that I’ve even parroted it myself in the past. But it’s only half true.

The OG contribution of simple sugars is certainly easy enough to calculate. Most brewers are probably aware that potential extract is typically given as a percentage of the potential extract of pure sucrose (46.21 point-gal/lb, 96.39 °P-L/kg). Let’s assume a volume of 20 L (5.28 gal) just to make the math easy. For a 5.0-5.5 gal batch volume, that will get us within 5%, which I think most brewers would concede is “close enough”.

(96.39 °P-L/kg)(0.454 kg)/(20 L) = 2.19 °P = 1.00856

So if your batch volume is 5.5 gal, eight points might be a better rule of thumb, but the oft-quoted value is essentially correct.

Determining how sugars will affect the FG gets a little more complicated, because, let’s face it, for most of us it’s been a while since high school chemistry. There also has to be an assumption made about how much of the sugar is consumed, and how much is fermented. I think it’s reasonable to assume that a healthy, active population of yeast will consume nearly all of the simple sugars available. I’m going to further assume that the sugar is being added during the anaerobic fermentation phase, so that nearly all of it will be fermented, as opposed to being used for aerobic respiration. The amount of ethanol generated then becomes a simple question of stoichiometry. The relevant reaction is:

C₁₂H₂₂O₁₁ + H₂O → 4C₂H₅OH + 4CO₂

So four moles of EtOH will be produced per mole of sucrose fermented. On a volumetric basis:

4((454 g)/(342.3 g/mol))(44.01 g/mol)/(0.789 g/mL) = 295.9 mL

Which is 1.458% ABV, incidentally. The reduction in density is a two-term weighted average:

(20000*1.0000 + 295.9*0.789)/(20000 + 295.9) = 0.9969

So when added to 20 L of water (or beer), a pound of fully-fermented sugar will actually reduce the SG by about 3.1 points, or 0.78°P. Maybe I’m splitting hairs here, but saying “two points” is off by more than 50%.

Ovens and Spices and Squash, Oh My!

webmaster — Sat, 22 Oct 2011 20:19:13 +0000

Frequent visitors will probably have noticed that I tend to be a bit of a traditionalist when it comes to beer recipes. After all, brewers are discovering new things to do with malts, hops, water, and yeast all the time. That approach does get a bit dull after a while though – especially when one starts brewing the same recipes 2-3 times/week. That’s probably a lot of the reason why I’m going to be brewing some wild and crazy beers over the next few weeks. That, and to build up some inventory before winter sets in.

First up is a “pumpkin pie” ale. The base beer is pretty straightforward, being more or less the grain bill from my American Amber, but with a single hop addition for bittering. The twists come from the addition of 58 oz (23% of the grist by weight) of canned pumpkin in the mash, and traditional holiday spices at flameout:

10 g grated ginger root
10 g whole cloves
5 g whole stick cinnamon
5 g coarsely crushed nutmeg

In addition to the pumpkin and spices, I wanted to further enhance the impression of pumpkin pie by giving the beer a pie-crust, graham-cracker finish. Biscuit malt would fit the bill perfectly, but getting some presented a problem. I do have a brand-spanking new “local” homebrew shop in Durango, but I wasn’t able to get there before brewday. The only solution was to try to make my own biscuit malt. Following Randy Mosher’s guidelines from Radical Brewing, I spread a pound of pale malt out on a tray and toasted it at 300°F. The entire house was immediately filled with the delightful aroma of non-enzymatic browning, progressing from sweet to bready to toasty to (unexpectedly) peanut butter. After 27 minutes the malt began to smell a little carbonized, so I took it out and left it spread out on the tray overnight. (Mosher mentions that some of the more odious aromas generated by the roasting process should be allowed to dissipate.) The finished product had a very nice biscuit character, although it may have been a little more “husky” than a commercial biscuit malt. Without tasting them side by side, it’s hard to say. The color did end up right where I wanted it at about 20 SRM according to the ol’ eyeball test.

Cargill Special Pale before and after toasting. SRM guide added digitally.

The brewday went off without a hitch. With such a high proportion of pumpkin in the mash, I was halfway expecting a stuck sparge or two, but my MLT handled it admirably. I did incorporate a long protein rest in order to ensure the pumpkin was fully converted, and ran off the wort a little more slowly than usual, just in case. It’s worth noting that according to the nutrition label on the cans, the pumpkin should have added ~0.8°P to the beer’s OG. BeerTools’ efficiency calculation doesn’t take that into account, hence the unusually high “mash efficiency” seen in the recipe.

Fall Classic recipe (PDF)

Reverse Mashing 2

webmaster — Sat, 15 Oct 2011 22:28:45 +0000

Background

Last time I toyed with the idea of “reverse mashing”, I found that an unheated kitchen isn’t a great place to do mashing experiments in the winter. Fortunately, I have a new toy available in the form of an oven with a “Warm” (170°F – 77°C) setting, and so I was able to perform two additional mashes utilizing longer rests.

Experimental Setup

For details on how the experiment was conducted, refer to the first post on the subject. Once again, the reverse mash was performed first, to determine the overall length of both mashes. Total time was 100 minutes, and the temperature profiles for all four mashes are shown below.

All other variables were kept constant between the two sets of mashes, with the exceptions of size and fermentation temperature. Since I needed starter wort for some upcoming brewing, I doubled the size of the mashes, to 1000 g of grain each. Fermentation took place in my new fermentation chamber, with the air temperature set for 20°C ± 1°C. The test worts were allowed to ferment for six days, then rested for one day at 8°C before gravity readings were taken.

Results

The reverse mash fermented from 12.0°P to 1.0093 SG, and the control from 12.4°P to 1.0068. As expected, the conventional step mash exhibited both higher efficiency and higher attenuation than the reverse mash. While the efficiency values for both new mashes are significantly improved, however, the attenuation values are similar. While increasing mash efficiency is desirable in most situations, home brewers may well find that a very short step mash provides fermentability on par with a more conventional longer mash, and that the time savings outweigh their comparatively modest financial investment. In a commercial brewing setting, however, the traditional lengthy mash with α- and β-amylase rests is clearly the better option.

Burning Beers

webmaster — Fri, 12 Aug 2011 03:26:13 +0000

Oh yeah, good stuff. Especially in cans. Labels were ordered today!

Dry Yeast Viability, Take Two

webmaster — Sat, 30 Jul 2011 00:24:48 +0000

Background

The last time I published the results of some dry yeast viability testing, I made the assumption that the reduction in viability that resulted from rehydrating the yeast in wort rather than water would have flavor impacts similar to under-pitching a liquid yeast culture. Shortly thereafter, James Spencer of Basic Brewing and Chris Colby of BYO Magazine threw down the fungal gauntlet by soliciting home brewers’ tasting results using dry yeasts, and I decided to take the additional step of actually fermenting and tasting beers using both techniques.

Experimental Setup

After brewing a recent IIPA with an OG of 18.9°P (recipe below) one gallon of wort was split into three half-gallon growlers and fermented using US-05. Two of the beers (U and 2U) were rehydrated in room-temperature wort, and the third (R) in room-temperature water. Based on the results of a methylene blue viability count, the pitching rates were:

R: Rehydrated, viable pitching rate 0.75 million/mL-°P
2U: Unrehydrated, viable pitching rate 0.73 million/mL-°P
U: Unrehydrated, viable pitching rate 0.34 million/mL-°P

The fermenters were covered with aluminum foil and left at room temperature, which varied from 16-20°C over the course of fermentation. To minimize variations between the fermentations, they were not agitated or aerated.

Results

Once again, I observed a substantial difference in viability, with the yeast rehydrated in water yielding a viability of 72.7%, and the wort-rehydrated yeast 48.8%. Interestingly, this is a higher viability than was seen with yeast rehydrated in lower-gravity wort, though it’s entirely possible that the variation is simply within the error associated with methylene blue testing.

Fermentations in all three beers proceeded similarly, although R began visible fermentation sooner than U or 2U. It did, however take the longest for krausen to fall in R – 11 days, versus 10 days in U and 8 days in 2U. This may be at least partially explained by the lower final gravity of R, as estimated by refractometer readings. U finished at 1.015, 2U at 1.014, and R at 1.013. There may be some inaccuracies introduced by the use of the refractometer formula, but since the OG of each beer was the same, the relationship between the FG values should be correct. Based on a hydrometer reading, the main “control” batch of beer fermented with Wyeast 1272 finished at 1.0145.

A blind tasting revealed that while similar, there were distinct differences between the three samples. All exhibited some degree of “musty” yeast off-aroma, with the smell being strongest in 2U and least prominent in U. 2U also had the highest degree of esters (particularly peach/apricot), and was the only sample to exhibit an acetaldehyde flavor. R was the cleanest overall, with the lowest level of “hot” alcohol character.

Conclusions

A substantial reduction in viability continues to be seen for dry yeast rehydrated in wort. There were also some of the characteristic effects of under-pitching in the wort-rehydrated beers, although the differences were less than in the liquid yeast pitching rate experiment.

These results were also featured on this week’s episode of Basic Brewing Radio.

RAWR! Recipe (PDF)

Practically a Mini-Mash

webmaster — Thu, 21 Jul 2011 14:46:50 +0000

At 335 pounds, Tuesday’s grain bill (for our next seasonal, a Smoked Vienna Lager) was the smallest I’ve done yet. It’s remarkable how much more smoothly the brew day goes when you only have two-thirds the usual amount of grist to deal with…

Until the backflow valve on a sump pump broke and I spent half an hour up to my shoulders in sewage, trying to figure out what was wrong, that is.

They still weigh 180 lb apiece though.

Original RI (°Bx):
Final RI (°Bx):
Wort correction factor:
(Default: 1.040)