Exhibition demonstrates how an empire of 50 million people was fed to prevent revolt

Grabbing something hot and tasty on the move? You have the ancient Romans to thank. "Street food" was their invention, generally enjoyed with wine, gambling or even prostitutes.

Food on the go was an integral part of daily life in the empire, from nibbling on salted peas while watching gladiators battle in the Colosseum, to grabbing a sausage or fried fish snack after a dip in Rome's baths.

Feeding an empire of about 50 million people was no mean feat, as an exhibition in Rome sets out to show. It is being held in conjunction with Milan's 2015 Universal Exhibition on the themes of food and agriculture, and runs until the end of October.

Food scarcity could trigger uprisings or even topple leaders, a risk Emperor Augustus (63 BC to AD 14) was unwilling to take. He made importing wheat, oil, wine and other foodstuffs a top priority, changing the face of Roman dining.

A typical day began with the jentaculum, or breakfast - salted bread, dried fruit and eggs washed down with milk or wine.

That was followed by a quick prandium, or lunch, grabbed at the thermopolia - forerunners of fast food restaurants - or popinae, wine bars frequented by the lower classes where customers could grab a bite, dabble in a bit of gambling, or pop upstairs for some sex.

After an afternoon's work or session at the thermal baths, the rich would throw sumptuous banquets, dining on anything from peacock tongues to baked mice.

The rest of the population supped on fresh vegetables, stews and, occasionally, meat.

"The logistics deployed by the Romans to feed themselves are fascinating," said Orietta Rossini, curator of the Ara Pacis exhibition, emphasizing how hard it was to keep a capital of 1 million people happy. The key lay in turning conquered Egypt into the empire's granary and ensuring wheat was transported cheaply to Rome all year round.

Private shipowners would carry up to 500 tonnes of wheat between Alexandria and Rome under the strict supervision of the state in an early example of today's partnerships between the private and public sectors, Rossini said.

This made the emperor "the sole distributor of daily bread, the only one responsible for the supply of provisions". Augustus boosted his popularity by distributing 35 kilos of wheat a month free to 20,000 citizens - free men over 17 years old.

Egypt's role was later passed on elsewhere, with grain shipped from Carthage in Tunisia to Rome's Ostia port in just three days and nights. Wine, sold at rock-bottom prices, was also imported, along with oil and meat.

The wealthy may have gone out of the way to impress with exotic dishes, but the empire's leaders were most fond of fruit and vegetables. "Emperor Tiberius loved cucumber, while Augustus loved asparagus", Rossini said.