Beer making lager cup el 90 percent of the world production of this beverage and at its base is a hybrid that combines the best of two yeasts and is able to ferment at low temperatures. But can you improve the efficiency of its production?
An international team of scientists, with Spanish participation, believes that yes and, thanks to a genetic-based research, has achieved identify a series of changes that applied to manufacturing would open the door to improve fermentation in this type of beera and therefore to improve its production.
The description of this process, based on the role played by the cell's "energy power station" – the mitochondrial genome – in the adaptation to temperature, is published in two articles in the journal Science Advances.
Among others, they are signed by scientists from the University of Wisconsin-Madison and Washington, in the USA, and the Institute of Agrochemistry and Food Technology (IATA) of the CSIC in Valencia.
Is about two basic research papers that analyze the role of mitochondria in temperature tolerance and that, later, have served to draw conclusions regarding beer.
Tolerance to temperature is very important for both plants and animals and microorganisms. Of the genes involved in this process, little is known, but in recent years it has been known that the mitochondrial genome plays a fundamental role, explains David Peris, an IATA researcher.
In fact, the mitochondria of organisms, such as yeasts, that 'live' in high temperatures is different from those that do less, so this already gives a clue to its importance.
With this base, the scientists, for their experiments, used three types of yeast, two of them ('Saccharomyces eubayanus' and 'Saccharomyces uvarum') tolerant to low temperatures and the other ('Saccharomyces cerevisiae') resistant to high temperatures; two are involved in the development of various types of beers.
According to Peris, for the manufacture of the lager type, a hybrid between S. cerevisiae and S. eubayanus yeasts is used, while for the ale type only the first one is used.
Depending on one type of beer or another, fermentation is achieved at different temperatures. Thus, ale beer leaven at temperatures between 15 and 25 degrees and beer lager at lower temperatures, between 12 and 18 degrees.
How to get beer to ferment at higher temperatures, which would imply faster manufacturing and less technical infrastructure? Manipulating genetically the yeast hybrid necessary for its elaboration and getting the mitochondrial genome of this one to be suitable for temperatures.
When a cross between two yeasts is made, the final copy 'inherits' the mitochondrial genome from one yeast or from another.
The researchers saw that if the hybrid 'inherits' the mitochondrial DNA of the yeast S. cerevisiae, it grows well at high temperatures, but badly when the grades go down; However, if the mitochondria are those of S. eubayanus or S. uvarum, the yeast is able to ferment very well at low temperatures, but not so much with heat.
Therefore, the scientists found that if they obtained in a laboratory that the mitochondrial genome of the hybrid was always that of the yeast S. cerevisiae, it would grow at high temperatures.
"We have managed to raise the temperatures of the process, which could therefore be faster and in which, in addition, cooling systems would be eliminated, which would increase productivity while reducing costs," sums up the Spanish scientist, who notes that they have created a patent on how to improve brewer stocks based on the data now published. EFE