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The chart demonstrates how the optimal separation of endosperm can be affected when bran and/or corn germ material is added into the endosperm stream.
The corn kernel contains a total of about 83 percent endosperm, the concentrated starch component of the kernel. An optimal endosperm stream for the most efficient production of ethanol is equal to at about 82 to 83 percent endosperm yield. Up to that level, nonfermentable bran and corn germ, which contain mostly fiber and oil, respectively, and are generally undesirable for fermentation, remain at minimal levels, as the lower lines in the chart show.
The oil and fiber levels start climbing with the attempt to gain a higher endosperm yield (and therefore overall starch yield). That means those nonfermentable germ and bran solids are being included in the starch stream, which can lower fermentation efficiency.
Think now about the aggregate mass of material going into the ethanol plant. The chart shows that once most of the recoverable endosperm has been captured via the optimal separation of the kernel’s components, returns diminish as more germ and bran are contained in the Degermed Debranned Corn (DDC) stream.
That’s why we refer to the 82 to 83 percent starch as the “the best separation.” It provides to the ethanol plant the optimal amount of fermentable starch in the endosperm stream and the lowest amounts of nonfermentable germ and bran.
There are two more benefits from that purer endosperm stream. The lower oil and fiber content means higher-value, higher protein meal than conventional DDGs, and it requires less drying. In addition the bran and germ captured before ethanol production is valued more highly in co-product markets.
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