comment 1

Saccharomyces eubayanus

Thanks to East Texas Red for sending me this article from the L.A. Times.

Scientists have found an elusive yeast in a forest in Argentina that is one of two yeasts that together formed the yeast used for making lager beer. Who knew?

Yeasts are quite mysterious to me. For a while I was keeping a sourdough monster in a jar in the kitchen, which I used to make bread each week. Every couple days, I’d feed it by emptying half the contents, adding water and flour and stirring it around. When I was ready to bake bread, I would use half the contents of the jar to proof the dough. One morning, the monster tried to take over the kitchen. It expanded out through the holes in the lid, flowed down the jar, across the counter and down the side of the cupboard to the floor. I’m not sure if aliens were involved.

1 Comment so far

  1. Salvelinas Fontinalis

    yeast is really neat stuff. You need it to make alcohol. The process is quite simple, yeast eats sugars and gives off carbon dioxide and alcohol in equal weights. Grape juice for example runs about 25% sugar and if you add a wine yeast it will produce about 12% alcohol and the same weight of carbon dioxide. Voila… wine. You get liquor by distilling the wine to remove the water content which leaves behind stuff that has a higher concentration of alcohol. The process is the same for beer except you use ground grains mixed with water instead of fruit juice. Stuff like vodka uses potatoes and water but in all these processes you need yeast. Then you can get fancy and if your base ingredient has a lot of starch but not much sugar you can increase the alcohol yield by either adding white sugar or by adding enzymes that convert starches to sugar.

    Not any old yeast will do though. Different yeasts behave differently. The alcohol making process is self limiting in that the alcohol produced is toxic to the yeast and at some level will simply kill the yeast and stop the process. Beer makers use yeasts that die at 5-6% alcohol. That is no good for wine makers though who need a strain of yeast that can keep working until alcohol concentrations reach as high as 18% (although most wine yeasts die at 12%). Different strains of yeasts will also add their own flavors to a brew and that makes yeast selection an art form. Your bread dough rises as a result of the same process, yeast eats sugar and makes CO2 which gets trapped in the dough causing CO2 and the dough rises. Add lots of sugar to the dough and the yeast will cause it to rise like mad. Of course bakers stop the whole process before much alcohol gets produced.

    Yeast also has the ability to completely put an end to global warming if we choose to do it. The secret here is that for every pound of alcohol produced the yeast produces a pound of carbon dioxide. No escaping it. Add up the billions of pounds of alcohol produced every year through fermentation and that is precisely how many billions of pounds of greenhouse gas we are cranking out each and every year. Ban fermenting and I think you can pretty much end global warming. Of course that leaves you with global cooling and when that happens you are gonna wish you had a nice shot of booze to warm you up. It would also leave you with some serious rioting in the streets when the beer stores all closed.

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