A further difference with wine and beer, is that wine tends to improve with age, whereas beer deteriorates. Most beer, within a year or so of bottling, forms an unpleasant ‘cardboard-like’ flavor (going ‘stale’ in a beer drinker’s lexicography). To help to extend how long a bottle or can of beer might last for, food scientists from China have genetically engineered a lager yeast so that the fungus produces a greater abundance of molecules.
A local dove enjoying some “Mythos” Hellenic lager. The street life of Athens is incredibly lively and vibrant.
READ MORE: Secret of a stable society happens to be beer
These molecules function to that protect the beer against staling, not only extending the hold time but, according to those who have tasted the beer, producing an improved flavor.
The role of yeast
With the beer production process, the fermentation of cereal extracts by the yeast Saccharomyces is the most important microbial process. The yeast produces ethanol as a fermentation end product. The final alcohol content is determined by comparing the initial and final specific gravities.
READ MORE: The genome of barley reveals secrets of better beer
New research
With the new technique, researchers have connected stale beer flavors to aldehyde compounds. These compounds include (E)-2-nonenal and acetaldehyde. These chemicals are generated by yeast during fermentation. The chemicals are also produced via chemical reactions occurring during beer storage.
A of DooM / Flickr.com (CC BY 2.0)
While there has been some experimentation using anti-oxidants, the research team led by Professor Qi Li attempted to genetically modify lager yeast so that it produces higher levels of a chemical called NADH. The theory runs that higher quantities of NADH will raise the activities of natural yeast enzymes which can convert the unwanted aldehydes into other compounds which will not create the stale flavor, the researchers.
To achieve the required modification of the yeast the science team deployed a genetic technique termed “overexpression.” Here they artificially increased the levels of different genes connected to NADH production. Specifically, the researchers focused on four genes that, when overexpressed, led to higher NADH levels. The yeast, when tested out, created beers which contained nearly 50 percent less acetaldehyde compared with beer produced using unmodified yeasts. Over time the beer had reduced staling. Research paper
The new technique has been documented in the Journal of Agricultural and Food Chemistry. The peer-reviewed research is titled “Higher NADH availability of lager yeast increases the flavor stability of beer.”
Other scientific secrets to a good beer
There are other factors which go towards forming a good beer. For example, scientists have shown how too high a temperature can ruin many a lager. To address the heat issue, scientists have looked into the issue of keeping yeast cool to overcome the problem that arises when yeast become hot this leads to change to the taste of a beer. Keeping yeast appropriately cool requires experimentation so that the right amount of nutrients are available.
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to winemaking, baking, and brewing fro a 1000 years.
Douglas Smith
Other branches of scientific research are charting the evolution of yeast in order to genetically create new yeasts suitable for lager brewing.
Many craft breweries are turning towards spectrophotometric technology in order to provide rapid and precise measurements so that distinctive beers can be created. A recent variant is a technology called UV-Vis spectrophotometry.
Essential Science
Colors returned as the storm passed
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue.
Last week we learned about stormquakes, which are powerful oceanic events are set to be categorized as a new meteorological phenomenon. This is based on new research centered on the U.S. coastline.
The week before we looked at the connection between inflammation and brain function. New research suggests there is a connection between the physiological state of the body and brain function.