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DISTILLERS
GRAINS DEFINED
Currently, nearly
3.8 million tons of distillers dry grains are created in domestic dry
grind ethanol production. For every bushel of corn made into ethanol,
18 pounds of DDGS are created and must maintain value to contribute
to plant profitability. The capacity for ethanol production is set to
double by 2005 and assuming that dry grind production doubles as well,
the potential supply of DDGS is almost 7 million tons.
The corn kernel is mostly starch at 61% of the wet weight,
with protein, fiber, corn oil and water making up the remaining 39%.
The dry grind ethanol process uses most of the starch present in the
corn kernel during ethanol fermentation, leaving protein, fat, minerals
and vitamins behind in a concentrated form. The forms of this ethanol
co-product are Corn Distillers Dried Grains (DDG), Corn Condensed Distillers
Solubles (CDS), Corn Distillers Dried Grains/ Solubles (DDGS), and Wet
Distillers Grains with solubles (WDGS).
DDGS PRODUCTION
Dry grind ethanol production begins by grinding corn
into a coarse flour and combining with water and enzymes. The enzymes
begin the conversion process of starch to sugar creating a mash that
is then cooked and sterilized. After cooling, yeast is mixed with the
mash to ferment the sugars into ethanol, carbon dioxide and other metabolites.
The fermented mash is then sent to distillation to extract the ethanol.
The mash is now considered spent mash which then goes onto either a
screen press or centrifuge, where as much liquid as possible is separated.
The liquid that is separated either goes back into the
cooking system and is sold as livestock feed, or is partially dehydrated
into syrup called condensed distillers solubles (CDS). The spent grains
can also be sold as livestock feed as wet distillers grains or dried,
in which case they are called distillers dried grains (DDG). If the
syrup is added to the wet distillers grains and then dried, the resulting
product is referred to as distillers dried grains with solubles (DDGS).
• Corn
Distillers Dried Grains (DDG) is obtained after the removal
of ethanol by distillation from the yeast fermentation of a grain
or a grain mixture by separating the resultant coarse grain fraction
of the whole stillage and drying it by methods employed in the grain
distilling industry.
• Corn Distillers Dried Grains with Solubles (DDGS)
is the product obtained after the removal of ethanol by distillation
from the yeast fermentation of a grain or grain mixture by condensing
and drying at least ¾ of the solids by the methods employed
in the grain distilling industry.
• Corn Condensed Distillers Solubles (CDS)
is the product obtained after the removal of ethanol by distillation
from the yeast fermentation of a grain or a grain mixture by condensing
the thin stillage fraction to a semi-solid.
Last
reviewed June 2, 2003
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