4. Dry Milling
First the grain is ground into flour, often
referred to as meal.
Next the meal is mixed with water to form a
mash. Enzymes are added to this mash to
convert the starch from the grain into sugar.
The mash is then sent to a high temperature
cooker to reduce bacteria levels.
After lowering the bacteria levels the mash
is cooled and transferred to the
fermentation tanks. Yeast is added during
to convert the sugar in to ethanol and
carbon dioxide.
5. Once fermentation is complete the
ethanol is separated from the remaining
mash and sent to distillation.
The ethanol is distilled and then mixed
with 5% gasoline to make it undrinkable.
This deters people from catching a buzz
at the local fill up station.
The remaining mash is sent off to be
processed into corn syrup and food for
livestock.
6.
7. Wet Milling
First the grain is soaked in water and dilute
sulfurous acid for 24 to 48 hours. This separates
the grain in to its many component parts.
The result is a slurry that is then sent through
grinders to separate out the germ. The
remaining fiber, gluten, and starch are further
separated from each other.
The starch is then sent to be fermented. The
fermentation process is similar to the
fermentation process of dry milling
The gluten, water, and fiber are further
processed to produced feed for livestock and
other products.
8.
9. Dry Milling vs Wet Milling
Dry
Short process time
Fairly simple
process
Low waste
production
Waste is used for
feeding livestock
Limited to certain
feedstocks
Wet
Many feedstocks
can be used
Process is more
involved
Longer process time
More waste
produced
Waste is used to
produce many things
