Is the contraction of "and", "'n'", capitalized in a title?
Solution 1:
If you are talking about taking a regular, lowercase phrase, like fish 'n' chips or rock 'n' roll, and putting it in a book title—say, Bottomfeeder's Guide to Fish 'n' Chips or My Ten-Year War with Rock 'n' Roll—it seems to me that 'n' is preferable to 'N'. That's because 'n' is a diminished form of and, which would normally be lowercased in a title if it were included in its entirety. It doesn't make much sense to me that removing two of the three letters in a conjunction would provide a compelling justification for capitalizing the remaining letter.
On the other hand, if you are asking about how to handle 'n' when it appears in a proper name, all bets are off. A quick look at fish 'n' chips outlets in the San Francisco Bay Area reveals the following treatments: Blue Bay Fish & Chips, Camelot Fish & Chips, The Codmother Fish & Chips, Fish 'n Frites, HS Fish & Chips, H.Salt, esq. Fish & Chips, Jay's Fish & Chips, Jonathan's Fish & Chips, London Fish N' Chips, Louisiana Fish & Chips, Piccadilly Fish & Chips, [Sausalito] Fish & Chips, Scousers Fish 'n Chips, Tugboat Fish & Chips, and Union Fish & Chips.
For those of you not keeping score at home, that adds up to twelve ampersands, two instances of 'n, and one instance of N'. Neither 'n' nor 'N' scores any matches at all. So if you're giving your fish 'n' chips shop a name, you can use & or you can use n or N, presumably with as many or as few apostrophes as you like.