Redeeming ma’ser sheni in Jerusalem’s Old City

Answer

It is forbidden to redeem pure ma’aser sheni inside the walls of the Old City, even today. Ma’aser sheni that has become impure, however, may be redeemed in the Old City; however, one may not intentionally defile the ma’aser sheni in order to redeem it. The practical solution, as brought down by the poskim, is as follows: Today it is permissible to defile fruit of tevel status when there is a concern of transgressing halachic prohibitions (chashah takala).

For this reason, you should: (1) Touch the food (produce) with wet hands before you set aside teruma and ma’aser, so that it becomes impure when it is still tevel, and then (2) Proceed with the regular process of setting aside teruma and ma’aser,  including redeeming the ma’aser sheni, even inside the walls of the Old City.