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[自然百科] 2014-11-10 啤酒是如何酿成的—12

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yeast is a critical ingredient in beer, it has the incredible ability to start the
fermentation process, which during brewing turn sugars into alcohol.

there have been examples of bottles of beer that have been found in shipwreck, that even
though they are hundreds of years old, they could take that bottle, isolate that yeast,
feed it some sugar and grow it up, allowing brewers to step back in time, and make beer
with these ancient yeast.

in the laboratory at Sierra Navada brewing, they propagate their own yeast. in fact, they
have been using the same strain since the day they began brewing in 1980.

so this is a yeast slurry that was taken out of the fermenter and so this is the active
yeast that's in one of our fermentation tanks, in the sample here, there are literally
milions of yeast cells, so in the milliliter there may be ten to fifteen millions of
cells even up to 40 or 50 millions of cells of yeast actively fermenting the sugars
into alcohol and carbon-dioxide.

Andy Tveekrem, brew master at Dogfish head craft brewery keeps an eye on his special strains.

brewers are basically yeast wranglers, that's what we do, we play with yeast all day.
if our yeast is happy, then the beer tastes good, if the yeast is not happy, then the
brewer is not happy.

the little fungi can be temperamental if they are not kept in proper enironment.

this is just for growing yeast. we put it in this clean-room environment which we tiled
all the walls. we put hepa-filtered air. so we don't have any microbial issue, there is
no mold or bacteria that can live in this room, it's very sanitary environment
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