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„ Ash in food refers to inorganic components that would remain when the food is oxidized (either by
burning or digestion). It's called ash because, if you did burn the food, that's what would make up the ash as we usually think of it, but the same inorganic components are present in the unburned food, so the same word is used to refer to them. Wheat, for comparison, has about 1.5-2.0% ash.”