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Content of Corn Starch
I have been getting some very low gravity (1.03-1.038). I have evaluated everything and narrowed the problem to a few things.
One is my corn. I buy it from a local supplier. It is #2 Dent.
I have had the corn analized and it came back 55.3% starch. I have always been told that starch content of corn was 70% or greater.
My question: Does the 70% include something else, like non convertable material that increases the starch content. Is my lab giving me just analysis of the fermentable material ?
Anyone with detailed knowledge out there that can tell me this is ok? Or do I just have some crap corn?
Mike
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3 Replies
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All starch is fermentable by standard distiller’s yeast if it is fully hydrolyzed during the mash. 55% sounds low to me, but I’ve never used #2 dent. What is the breakdown of the other 45%? Starch content is usually given on a dry basis, so if your lab’s analysis includes moisture content (~15% typically), that could lower the overall reported starch content. There are a lot of varietals of corn, and a lot of variety within each. For example, a heavily fertilized crop will generally have a higher protein content (and thus lower starch) than a moderately fertilized one, all else being equal. That being said, I believe feed corn is generally #2 dent, so you could have purchased a high protein corn – not necessarily crap corn, but better suited to pigs than yeast.
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Post you mashing protocol.
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Dent (or field) corns vary in their starch content. Yellow hard dent intended as feed corn is usually bred for higher protein content, hence less starch. Yellow hard dent intended for food processing and brewing is bred for higher starch and lower protein, since the sugar from starch conversion is the desirable product, and the protein is in the waste stream.
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