I've been looking around the Internet. Some websites say that foods is incorrect but others say it is correct.
Food in its commonest sense is a non-countable noun, with all the effects of that. It's already a plural. You would eat "some food" not "a food". You would say "less food" not "fewer foods".
However, there is a less common usage where "a food" means "a type of food":
"Cheese is a food made from milk"
... and in this form, you can pluralise it ...
"Italy is the source of many delicious foods -- pizza, pasta, salami, biscotti..."
For comparison, think of "a people" - Are there meta-plurals beyond "peoples"?
Kraft Foods ... Lots of byspels of the plural for foods. It's common and correct.