Wine...
about 32 billion bottles are bought and sold around the world each year
each bottle contains about two and a
half pounds of grapes
but before you get here the process
starts here where winemakers work
towards creating the perfect blend of
aroma, color and taste. I would say the trickiest part of making wine is getting
the flavors right
A big part in getting that right is not
only the grapes
but the fermentation of those grapes.
Right now or in the
UC Davis research winery and we are
looking at the fermentation tanks
these are our production fermentation tanks
inside these tanks the yeast converts the sugar in grapes
into alcohol.  So here we have our high-tech monitoring system for all these
tanks, you can see here you can select
individual tank, you can see the volume of the tank
the temperature of the tank. Biochemists monitor the yeast as they battle what seems to be a
microbial war
Yeast are these incredible microbial
juggernauts they are
they suck up all the nutrients they suck
up all the oxygen they're incredibly
dominant fermentation and on top of that
they make alcohol so there
knocking back the growth everybody they can just cycle and grow very very quickly
get a fermentation going and finish a
fermentation very quickly
If all goes well fermentation can be
complete in two to three weeks
but sometimes the yeast lose the
battle.  As a winemaker
that's not great cause really what you want yeast to do is just get in there kick butt
and finish the fermentation.
A problem that has plagued the wine
industry for centuries
is when fermentation stops. So one of
the big problems with the industry is
stuck fermentation or an arrested
fermentation where sugar is left behind
Now
for the first time yeast geneticist Linda Bisson and her team
have discovered what triggers stuck
fermentation.
Researchers learned that an abnormal
protein is created in yeast by
bacteria in the wine
these proteins can reproduce themselves inside of the yeast
causing the yeast to slow down or stop converting sugar into alcohol
when the yeast stop working they become stressed and give off a sulfur smell
like rotten eggs, clams and bad
vegetables
excess sugar is left behind and the wine becomes too sweet
So we think what the yeast are doing is they're taking that signal from the
bacteria
and slowing their metabolism down
slightly slowing down their uptake amino
acids slowing down their uptake of
oxygen and slowing the fermented 
processes a little bit.
Now that they know what's causing it,
researchers are working to create
yeast strains that will ignore the
bacteria, not make the protein and keep
on working.
The industry simply wants the problem solved, they don't wanna have bad sectors
of their vineyards that give them
lower quality wine.
And we can all drink to that!  This is Inside Science TV.
