The most interesting bit of chemistry relevant to brewing a wheat beer involves the transformation of ferulic acid into 4-vinyl guaiacol. (The chemistry with regards to the esters, including the “banana ester” (iso-amyl acetate), is the pretty much the same as in “regular” ales.) However, a look at a variety of related molecules — where they come from and what they get converted into — is interesting and may be helpful to brewers looking to track the source of off flavors when they appear.
Archives for September 2013
This is the fifth part in a series on German wheat beers. The first part was posted September 3rd.
If you were to follow all of the instructions on making a classic German hefe-weizen, but fermented the beer with an English ale yeast strain, America ale yeast strain or lager strain, you would not yield a beer with the typical wheat beer flavor and aroma. Brewing a hefe-weizen requires a yeast that will produce the spicy, clove-like, phenolic aroma and flavor we all associate with wheat beers.
This flavor comes from 4-vinyl guaiacol (4VG) and other similar phenolic molecules (including 4-vinyl phenol) and these are only produced in detectable quantities by certain yeast strains. These strains contain a variant of a gene (named POF, for phenolic off flavor) that is considered a flaw in most other beer yeast strains.
The POF gene codes for the enzyme ferulic acid decarboxylase. As the name implies, the enzyme catalyses a reaction in which a carboxyl group is removed from ferulic acid, leaving 4-vinyl guaiacol (4VG). So, if you have ferulic acid in your wort, fermenting with a POF+ yeast strain will give you 4VG in your beer. Fermenting with a POF- strain, a strain in which the enzyme is not functional, will yield a “clean” beer, with levels of 4VG below detection (as in most American wheat beers). Lager yeast strains and most “normal” ale strains are POF-, while wheat beer strains are POF+. (Some wine strains are POF+.)
Of course, to brew a hefe-weizen, you don’t need to know the genetics or biochemistry of what is going on— all you need to do is select an appropriate yeast strain. And, this isn’t hard since all the relevant yeast strains have either “hefe-weizen,” “weizen” or “wheat beer” in their names.
Homebrewers aerate their wort in a variety of ways. Some simply shake their carboys or pour their wort back and forth between sanitized buckets. At the other end of the sophistication scale, some homebrewers have in-line aeration stones placed near the outflow end of their counterflow or plate chiller. Every bit of wort headed to the kettle flows past the stone, thoroughly aerating it. For many homebrewers, however, there’s a middle ground.
Lots of homebrewers, like me, have an aeration stone that they place in their fermenter after the chilled wort has been transferred into it. An aquarium pump or an oxygen cylinder pushes air or oxygen through a HEPA filter on it’s way to the aeration stone. This is an effective way to aerate homebrew wort, but a couple simple tips can help homebrewers get the most out of a setup like this.
Longmont, Colorado is home to the Left Hand Brewing Company and Oskar Blues Brewery, both well-known to craft beer drinkers. The recent flooding in Colorado, which has left 4 dead and 172 missing as of Saturday morning, has also caused Governor John Hickenlooper to evacuate thousands from Longmont. (Incidentally, Hickenlooper is one of the founders of Wynkoop Brewing Company in Denver)
The breweries, via their Facebook pages and Twitter, have been keeping interested beer drinkers updated on their status. [Read more…]
I like this recipe for two reasons. First of all, it’s a tasty beer with low alcohol and low calories. Second, it’s a beer that professional brewers would be hard-pressed to duplicate. Malted wheat and malted rye are notoriously sticky – especially the rye, which I discovered can be quite viscous. The advantage to the viscosity is that we can use rye to boost the body of low gravity beers to make them less watery and more substantial. [Read more…]
This post is part of a series on German wheat beers.
As I mentioned in the post that began this series, in many ways brewing a German hefe-weizen is similar to brewing any other ale. And conducting the boil is one part of the brewday where this is mostly true.
As with the vast majority of beers, you want a vigorous boil to sanitize the wort, coagulate the break material and isomerize the alpha acids from the hops. (There are also a host a minor goals that the boil accomplishes.) There is one minor twist when boiling a hefe-weizen wort.
Two differences between a wheat beer wort and a “regular” ale wort are that a hefeweizen wort contains more protein and fewer tannins. Wheat malt has a higher protein content and the low hopping rate (typically 20 IBUs or less) contributes fewer hop-derived tannins to the wort. Because protein-tannin complexes are part of what you want to precipitate in the boil, you should boil your wort vigorously — at home for at least 90 minutes (and perhaps up to 120 minutes). Commercial brewers, if they employ an external calandria, can cut the time to 70 or 80 minutes. Other than extending the boil longer than some ales, the hefe-weizen boil can be handled as you normally would.
The beginning of “homebrewing season” is usually a time of great anticipation, a time to fill some fermenters and once again hear the gurgling of air locks in your house. But sometimes even the most dedicated homebrewer can feel trapped in a rut. If it seems like you are facing your upcoming brewing sessions with less than the usual anticipation, check out these 5 things to shake up your routine and reinvigorate your interest.
Here is my “straight up” hefe-weizen recipe — everything I love about German hefe-weizens, but brewed fresh at my house. This recipe uses a decoction mash, but you can simplify it to a step infusion mash if you’d like. If you find undermodified Pilsner malt to use in the recipe, all the better.
All-grain; English units
A classic Munich-style hefe-weizen. The brewing methods described here are mostly traditional. A decoction mash is employed, for example. However, some steps are simplified. The beer is primed with sugar, for example, rather than Spiese (fermenting wort, usually inoculated with lager yeast). If you follow these steps, your beer’s aroma will show a balance between the clove and banana character typical in hefe-weizens. You will need to bottle this in heavy bottles, so enjoy some commercial hefe-weizens before brewday and while the beer is fermenting.
This is the third part in a series on German wheat beers. The first part was posted September 3rd.
German hefe-weizens are made from wheat malt and barley malt. A beer must have at least 50% wheat malt to be called a hefe-weizen and a 70:30 wheat to barley ratio is the classic Munich-style blend. Hefe-weizens are normally 11–13 °Plato (OG 1.044–1.052), with some examples being slightly higher.
Mashing the grains for a German wheat beer differs in two respects from most “normal” ale mashes. First, your wheat malt is large, naked (huskless) and sticky (contains more gluten), compared to barley malts. These differences can cause problems when crushing and when lautering. Secondly, adding a rest — called a ferulic acid rest — to you mash program can influence the yeast-derived character in your beer. (Specifically, the clove aspect of the beer’s aroma will be enhanced.)
My recent article on reiterated mashing received some interesting comments from readers. Several commented that adapting the idea to a brew-in-a-bag (BIAB) approach might work. I’m not set up to do BIAB brews, so I haven’t tried it. But, I suspect it would probably basically work, although I would wonder if the extract efficiency would be high enough to be worthwhile. Hopefully someone will try it and take good notes. At minimum, you should be able to make a BIAB beer at almost double the maximum specific gravity as is normally obtainable (for the same length boil). Besides the grain bill, the amount of water in the kettle before and after each mash, the specific gravity after the first mash and the progress of specific gravity increase during the second mash would all be interesting.