When the French Riviera town of Menton prepares to host its lemon festival each year, it assembles more than 140 tons of citrus to build the ornate floats and showy park displays that attract thousands to the Fete du Citron. “Honestly, we prefer that people taste our lemons rather than look at them on display,” said Marine Krenc, an events manager for Menton’s tourism office. Menton was once a leading lemon-growing region in Europe, with a global reputation and exports as far as the United States and Russia in the 18th century.