|MadSci Network: Agricultural Sciences|
The graying and/or blackening of potatoes following cooking is referred to as after-cooking darkening. The cause of after-cooking darkening has been studied by scientists since the early 1900s. Today, it is generally accepted that after-cooking darkening is the result of a dark colored complex of ferric iron and an orthodihydric phenol (probably chlorogenic acid). The mechanism of after-cooking darkening is influenced by other factors as well. Such things as iron content, amount of orthodiphenols, presence of organic acids and pH are also probably involved. If you would like an indepth discussion of after-cooking darkening the book Potato Processing, 3rd Edition, William F. Talburt and Ora Smith, The AVI Publishing Company, Inc, Westport, CT is an excellent resource. The book is out of print, but many University Libraries should be able to get a copy. I hope this information provides a brief answer to your question. Sincerely, Al Bushway Professor of Food Science
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