Palestinian food businesses in the United States report having been flooded with one-star reviews online, and Israeli restaurants in a few cities beyond Philadelphia have been tagged for boycotts on social media.

“We tend to think of food as humanizing but when there is conflict, food becomes part of the conflict,” said Ari Ariel, an associate professor at the University of Iowa who has written about and lectured on what he calls the Hummus Wars. The battle began in 2009, when Lebanon claimed Israel was trying to steal its national dish, turning the dip of sesame paste and chickpeas into an avatar of hostilities in the Middle East.