|Corn can be used for the brewing of beer in two forms. It can be used as a source of starch and as a source of
sugar. Corn for brewing can be used in the form of grits, flour, torrified, flaked, or syrups. It is a common adjunct
in mass-market beers produced in North America, and is typically used as up to 20% of the grist. Corn produces a
lighter color and flavor in beer than barley malt does.
Corn grits, more specifically, are the most extensively used form of corn adjunct in the US and Canada. They are
produced in a dry milling process that removes the outer layers and the germ, the latter being oil-rich and
therefore a source of potential rancidity. The resultant particles are essentially pure endosperm.
At very high cost, refined corn starch is a product of the wet-milling of corn. It comprises a very fine powder that is
somewhat challenging to handle commercially. Treatment of corn (and other cereals) at around 500°F in a
process known as torrification leads to a rapid expansion (“popping”) of the endosperm, thereby gelatinizing the
starch. Subsequent rolling of the grain is used to produce flakes.
Phenolic flavors and aromas are often described as clove-like, medicinal, smoky, or “band-aid” and are
considered off-flavors in most beer styles. Beer always contains some form of phenol; polyphenols, such as
tannins, are derived directly from hops and malt. Low levels of polyphenol can contribute to mouthfeel, whereas
high levels can cause a drying, mouth-puckering astringency.
When a beer is described as phenolic, it is usually with reference to volatile phenols. Volatile phenols have
low flavor and aroma thresholds and most people taste and smell them at very low concentrations,
sometimes under 10 parts per billion.
Although volatile phenols are generally not desirable, certain of these are sought after in particular beer types.
There are three main sources of volatile phenols: ingredients, chemical taints, and yeasts and bacteria.
Chillproofing is a term used when a beer undergoes a process to protect its clarity or brightness. This occurs
when the beer is cooled to very low temperatures approaching 32°F. With most beers, chillproofing is a very
important part of the modern brewing process. The earliest use of a form of chillproofing occurred in the
mid-19th century with the brewing of lighter lager beers.
The original pilsner beers were stored in caves packed with ice, which helped to chillproof the beer through cold
aging. Traditionally beers are chillproofed by being stored at 0°C or below for long periods of many weeks or
months. During this time protein and polyphenols derived from malt in the beer coagulate to form larger molecules,
which can then be removed by filtration. In the days before beer filtration, the beer was aged long enough for the
particles to simply settle out. Most filtered beers are clear and bright when bottled or kegged, but without
chillproofing the protein–polyphenol coagulation occurs in the package, and the beer becomes hazy within weeks.
In modern beer production, processing aids are used to shorten the chillproofing process from weeks or months to
only a few days. Proteolytic enzymes, which break down larger protein molecules, were some of the first
chillproofing aids. Nowadays protein and polyphenol adsorbing materials are often used.
Hope you found this month's column of interest. If you have any questions about beer or brewing
or just want to submit a word for me to discuss here just e-mail it to me.
Thanks and Cheers!
|Corn in Beer - Phenolic Flavors - Chillproofing
|A new column by
|Jack O'Reilly attended the
famous Siebel Institute/ World
Brewing Academy in Chicago.
|I'm very excited to be part of the BeerNexus team. I think my many years in the
beer business both as a brewer and manger will enable me to explain and
investigate many topics of interest for those who really love craft beer.
Hope you join me every month.
More by Jack: #1, #2, #3, #4, #5, #6, #7, #8, #9, #10, #11, #12, #13, #14,
#15, #16, #17, #18, #19, #20, #21, #22, #23