"Legally" you are not allowed to bring food from the ship to shore. It is an agricultural law (same in the U.S.) so no foreign critters, insects or disease is transported into the country.
However, many people will take food from the morning buffet and make sandwiches to take ashore.
I would advise not to take fresh fruit on shore. If the local authorities find that they won't be as lenient as a ham sandwich.
Also, stay away from mayo on the sandwiches. You don't want to get sick.
My advice: Try some of the local food. It may be a pleasant surprise.