I searched Google Books for "fresh butter" (it's not case-sensitive), and got 20 results, of which 8 had the word "Butter" capitalised (but only one of them also capitalised "Fresh"). I think at least a couple of the citations were duplicates.
On that basis, I'd say OP's example wasn't abnormal, but it wasn't "the norm" either.
The full story of how standard capitalisation evolved/reduced several hundred years ago is discussed (sometimes cogently) in tchrist's link above. A key point made by user:holgate there is...
The Change didn't occur at once, by some top-down Decree, but happened over a long period of Time, and according to Fashion. Regular Nouns go from Capitalised to lower-case; emphasised Nouns go from Italicised-capitalised to italicised or roman lower-case, depending on House Stile. Certain proper Nouns go from ꜱᴍᴀʟʟ ᴄᴀᴘꜱ to Capitalised.
I've no reason to doubt "holgate" is correct in saying David Foxon's Pope and the Early Eighteenth-Century Book Trade is the canonical Work on this Topic.