How do I allocate each post subject to a predefined menu tab?

I’m building a new magazine style website which will have a number of menu tabs (pages) – one for each of ten subjects, like food, travel, theatre, etc, etc.
How can each post written on one of the subjects be allocated (published) to that particular relevant menu tab (page) automatically by the author?
The website is not yet live in draft form, so therefore no link.
Thank you in advance.