No.

Just because you like food threads is not a reason to have a new prefix.

The number of food threads is quite small.

Sould we have specific prefixes for threads about computers, banjos, gardening, moving house, seagull guitars, feeling down, etc, etc?

There are already enough prefixes. The 'Super Search' works pretty well and should allow you to easily enough.

Otherwise have a look at one of the very many 'foodie' discussion sites and newsgroups.

Jeff