Continuing our discussion of off-flavors, we'll take look at diacetyl it's great on microwave popcorn, but as all brewers know, this "buttery" off-flavor has no place in beer.
Diacetyl (2,3-butanedione) is well known as the “butter” compound in microwave popcorn. It presents itself as a buttery or butterscotch flavor in beer. It’s in the vicinal diketone (VDK) category of…
A problem that all brewers face is managing and eliminating off-flavors. For the first post of this series, we'll take a look at DMS.
What is it?
DMS (dimethyl sulfide) exhibits itself as a canned vegetable or creamed corn flavor in beer.
How does it form in beer?
All malt contains a variant of the amino acid methionine called S-methyl methionine (…
Continuing our series on off-flavors we're going to look at what happens and how to deal with beer-spoiling bacteria and wild yeast infect your brew.
What is it?
Infection occurs when beer-spoiling bacteria or wild yeast make it into beer and start competing with cultured yeast for sugars. The typical off-flavors to look out for are sour and/or diacetyl (buttery). Other…
Isoamyl acetate is the ester responsible for the banana-flavor. Typically described as the “circus peanuts” flavor or the dominate flavor in german-style hefeweizens.
How does it form in beer?
This compound forms by the condensation of acetyl CoA and isoamyl alcohol during fermentation. Most esters form in beer due to the reduction of a carboxylic acid and ethanol. This…
The papery off-flavor occurs when beer is oxidized. It can also present itself as a cardboard flavor or even as a sweet stone fruit flavor.
How does it form in beer?
The major compound that causes the oxidized flavor is trans-2-nonenal (pictured above). This flavor is typically formed in packaging when stored at elevated temperatures (above 40 F) for any period of time due to…
This is a High-Performance Liquid Chromatograph (HPLC). This awesome piece of analytical equipment can measure the concentration of different compounds present in beer, wort, and hops. We use it to measure the concentration of humulone, cohumulone, lupulone, and colupulone in hops. These are collectively known as alpha and beta acids in brewing terms. The alpha acids (…
The grid like pattern on the Stochasticity Project Grapefruit Slam IPA bottle label is a two-dimensional random walk. Random walks explain observed random behaviors and processes and are the most elementary way of showing recorded stochastic activity. Random walks allow us to find patterns in behaviors and processes that seem random. In short, randomness isn't really that random after all.
Titrations need four things: sample, acid, base, and an indicator. You add acid to a base and indicator-infused sample and by knowing the exact volume of acid added to neutralize the basic solution and change from pink to blue, you can determine how much of a substance is in solution. Titrations are used to determine the total amount of hardness, calcium, and alkalinity in brewing water. This is…
Triangle testing is an essential part of our sensory program. It involves a set of three samples - one sample is a test and the other two are experimental controls which are presented blind to the taster. The goal for the taster is to try to determine which sample tastes different from the other two. This test is an important, unbiased way of determining if a change in the brewing process…
UV-vis spectrophotometers are the swiss army knives of brewing chemistry because of the sheer amount of compounds it can analyze for and for the cheaper price tag.
Spectrophotometers (“specs” for short) are used to measure the amount of iso-alpha acids in beer, which gives you IBUs.
Specs can also measure, in wort and beer, the amount of free amino…
