What is the actual form of 'bound niacin' in unprocessed corn?
I am trying to find out how the niacin is 'bound' in unprocessed corn as in what chemical form. In detail, I want to understand how processing the raw form of corn such as nixtamalization and boiling 'unbinds' the niacin into more easily absorbable form for humans and animals. In another words, I want to know the chemical form of 'bound form of niacin' which turns into the chemical form of 'unbound form of niacin' via some type of post-harvest processing.
I read through Maize in human nutrition (Food and Agriculture Organization oF the United Nations, 1992: https://www.fao.org/4/T0395E/T0395E00.htm) to find out what I want, but I could not really find the information I want.
Does anyone know about this?
Thanks.