score:2
As a matter of anecdote, my relatives brought whole bags of fruit from e.g. Hong Kong. Don't think you need to declare it or anything.
It is customary to bring food from travels in Russia, even if there exist laws that de jure prohibit it.
Upvote:4
The food you're bringing should be ok.
There's no mention of fruit in the list of prohibited items on the Russian customs website, and since that's the ultimate authority (albeit with a strange English translation) my answer is, it's ok.
I found no mention of fruit or peanut butter anywhere else (though those were all traveller-type blogs) including Frommers, however IATA says you can't bring fruit into Russia.