Yosef Karo

“ Paragraph 6 - In a city with a majority of non-Jews, we assume that what is brought is brought for the majority. Rem"a: If it is 50-50 or it is known to have been brought for both [Jews and non-Jews] , it is forbidden (Beit Yosef and the Sma"g) .
סעיף ו - בעיר שרבה אינם יהודים, מן הסתם כל המביא לצרך הרב מביא. הגה: מחצה על מחצה, או שידוע שלקט לצרך שניהם, אסור (בית יוסף וסמ"ג) .
Paragraph 7 - If it is questionable whether it came from outside of the techum, it is a non-Jew who lives within the city, and there are fruits within the city, it is permitted. ”