The excerpt from the passage that includes an example of metonymy is:
“The twelve children steamed away from the port of Naples on a freighter overloaded with barrels of wine, olive oil and tons of pasta.”
In this excerpt, the terms "barrels of wine," "olive oil," and "pasta" are examples of metonymy because they represent broader concepts related to Italian culture and cuisine, using specific items to refer to the culture or lifestyle associated with them.