Secrets of a fresh beer
According to the latest American Chemical Society (ACS) Weekly PressPac, scientists in Venezuela have found a way to keep beer taste fresher for long times. Here is a link to this PressPac, from which you'll be able to read a very short note simply titled 'Keeping beer fresher.' The researchers found that carbohydrate derivatives known as alpha-dicarbonyls were responsible for 'the decline in fresh flavor that occurs as beer ages.' If these chemists are right, you'll be able to drink a good beer months after buying it. But read more...
As the scientists focused their efforts on Pilsner beer, you can see on the left a picture of glasses filled with the Original Pilsner Urquell. (Credit: Mohylek, link to a larger version). This illustration is provided free of charge via the Pilsener page on Wikipedia, which states that "Pilsner or pilsener is a pale lager, developed in the 19th century in the city of Pilsen, Bohemia (Plzeň in the Czech Republic)."
The lead researcher, Adriana Bravo, is the Scientific Support General Manager at one of Venezuela's largest private companies, Empresas Polar, with annual sales exceeding $6 billion. She's also collaborating with other scientists from the Universidad Simón Bolívar in Caracas, Venezuela. Please note that the two sites are in Spanish. But here is a English link to the Empresas Polar company history.
Even if she has no -- apparent -- website, Bravo is able to talk about this research project with journalists. In a short article from Tom Avril for the Philadelphia Inquirer, "Taking the bite out of bad brews" (June 2, 2008), she said that "The fresh flavor of a beer is a very delicate equilibrium."
For more information, let's turn to a Matt Kaplan's article in Nature News, "Beer gets fresh approach" (June 2, 2008). The author explains how the researchers linked the chemical Maillard reaction to the degradation of taste of beer as it aged. According to Wikipedia, this "a chemical reaction between an amino acid and a reducing sugar, usually requiring heat."
Bravo and her team carefully looked at this chemical reaction and got some surprises. "'The Maillard reaction is one that is usually seen in baking and roasting where temperatures are high -- that it was taking place during beer storage where temperatures were 15-20 °C was really surprising,' comments Bravo. Bravo and her colleagues suspected that intermediates of the Maillard reaction, called alpha-dicarbonyls, are involved in the change in flavour, because they had observed a chemical marker of the reaction increasing in beer as it aged and deteriorated. They could not be certain, however, without putting a stop to the Maillard reaction."
So the researchers tried to manipulate this Maillard reaction by adding the drug aminoguanidine and a chemical called 1,2-diaminobenzene (1,2-DAB) to the beer. "Over 105 days they detected the appearance of 11 different alpha-dicarbonyls, some of which increased in concentration continuously as the beer aged. This left the team wondering if these highly reactive alpha-dicarbonyls were the ones involved in forming the off-flavours, and what compounds were formed when they reacted with the rest of the beer."
Apparently, beer was tasting better for longer times. But the team doesn't have a definitive explanation. "'How these compounds, and the many that are not yet identified, are combining to generate the ageing flavours still eludes us,' says Bravo, 'but we are hoping to prolong the fresh beer flavour for longer by manipulating the Maillard reaction.'"
This research work has been accepted by the Journal of Agriculture and Food Chemistry and published as an ASAP article (As Soon As Publishable) under the name "Formation of α-Dicarbonyl Compounds in Beer during Storage of Pilsner" on May 8, 2008. Here is the beginning of the abstract. "With the aim of determining the formation of α-dicarbonyl intermediates during beer aging on the shelf, α-dicarbonyls were identified and quantified after derivatization with 1,2-diaminobenze to generate quinoxalines. The sensory effects of α-dicarbonyls were evaluated by the quantification of key Strecker aldehydes and by GC-olfactometry (GCO)analysis of beer headspace using solid phase microextraction."
If this abstract 'wets your appetite,' here are two links to the full article, in its HTML version and in its PDF version (11 pages, 572 KB).
Sources: American Chemical Society's Weekly PressPac, May 28, 2008; Matt Kaplan, Nature News, June 2, 2008; and various websites
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