It is Oktoberfest season here in Munich and beer consumption is at its highest. Beer is one of the world’s oldest beverages, with evidence of its existence dating back to 5000 BC in ancient Egypt and Mesopotamia. It is made by the fermentation of sugars usually derived from malted barley to produce ethanol and carbon dioxide. Hops are often added to increase bitterness and they contribute to that thick foamy head we see on the surface of beers. Various strains of yeast carry out the fermentation process and these differ in terms of their growth rate and resultant ester production. Esters are what contributes to the assortment of fragrances associated with beer.
Brewing beer is indeed a science. There are an array of parameters that affect the brewing process and resultant flavour of the beer. These include minerals in the water, the temperature of fermentation, the strain of yeast used, the amount of aeration and the length of fermentation. To gain an insight on the level of science involved, check out Chad Yacobson’s blog. He did a Masters degree in brewing and distilling in Edinburgh and recorded his laboratory findings in an open-source fashion, mainly a wordpress blog. It features an array of agar plates with a dizzying variety of cultivated yeast colonies of differing shapes and colours. He also had to smell each plate, and the esters the yeast produces can give rise to scents like “Hawaiian punch” and “cocoa buttery” aromas. Not too bad a scientific project! He focused in particular on a wild yeast strain called Brettanomyces spp. and now has started his own business in Colorado selling Brettanomyces-fermented beers.
It is interesting however that with the current ease in genetic manipulation, especially of simple organisms like yeast, that not a single beer on the market is made using genetically-modified yeast. This is mainly due to the negative impression people have on genetically-modified foods. This may change in the near future though as the US FDA have established some headway into getting these genetically-modified yeasts into the market. Already, some wines are being produced using a genetically-modified strain of yeast called ML101 which is deficient in a gene that produces a headache-inducing chemical.
In parallel with brewing beer, scientists have recently found a way to induce yeast to ferment sugars into opiates. John Dueber’s group at the University of California, Berkeley, and the lab of Vincent Martin of Concordia University in Montreal, Canada, have revealed all steps aside from one of an engineered yeast pathway that converts glucose to morphine. Morphine is currently produced from poppy, and this advance would make it much easier and cheaper to produce the analgesic. But of course this generates the obvious risk of home beer-brewers making their own pain-numbing concoctions. Not to mention the wide network of illicit drug dealers that would not hesitate to delve into the science of yeast fermentation to produce opiates for the current market – 16 million people take opiates illegally.
With synthetic biology on the rise, it is indeed necessary to enforce strict regulations on its applications. When it comes to brewing better beer however, I say bring on those GM yeast!