Quitting Yeast To Winemakers: I Blame Protein

A team of researchers from the University of California at Davis have made a significant discovery about the mechanism responsible for halting the fermentation process of yeast, a bane for wine producers who, until now, had no explanation for their occasionally quitting catalyst.


The culprit, UC Davis yeast geneticist Linda Bisson said in a UC Davis release, is self-reproducing producing protein called prion (PREE’on).


“The discover of this process really gives us a clue to how stuck fermentation can be avoided,” Bisson said. “Our goal now is to find yeast strains that essentially ignore the signal initiated by the bacteria and do not form the prion, but instead power on through the fermentation.”

The researchers found that, at times, yeast undergoes significant stress in the fermentation. Like vultures circling viticulture fortunes, bacteria present in fermentation “convince” yeast to produce prion.


Prion does it’s dirty work, the study said, by suppressing the yeast’s ability to break down glucose by allowing it to process other elements. Normally, the type of yeast used in winemaking, brewing and breadmaking works the opposite way: other forms of processing are suppressed, focusing the yeast’s efforts on breaking down glucose.


“As sugar metabolism slows down, conditions in the fermenting wine are more conducive to bacterial growth, and the yeast benefit by gaining the ability to metabolize glucose but also other carbon sources as well – maintaining and extending their lifespan.”


Prion essentially opens up yeast’s diet options, welcoming to the fold other metabolism meas besides glucose and allowing it yeast to live longer. Initial solutions for winemakers, researchers said, include altering levels of sulfur dioxide in order to knock out bacteria which can trigger prion production. “They can also be careful about blending grapes from vineyards known to have certain bacterial strains,” the study said, “or they could add yeast strains that have the ability to overpower these bacteria.”



Original: Snooth – Articles


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