GENTILCORE: You can’t imagine Italian food without it. And yet most of these dishes, such as pasta al pomodoro, are fairly recent — from the 1870s or ’80s. Italian immigrants arriving in New York City or Boston were the first generation to eat these dishes as daily things. Making a rich meat sauce with maybe the addition of tomato paste, that Sunday gravy style, is something that happens only in the 20th century.

Gentilcore spoke with Ideas by phone from Arezzo, Italy, where he is currently doing research.

Gentilcore may now know more about the tomato’s long journey through Italy than anyone else, and has a particular eyeall details that really surprise. “I like provoking,” he says. “There are historians who write textbooks to propound myths about history. Then there are historians who like to break down myths and preconceptions. I’m not saying I’m doing that. It’s too grandiose. But I can’t resist the odd thing.”

As tends to happen with food trends, tomatoes caught on. They gradually entered the diet, bringing color to pizza and pasta. They became a major industry — today worth $2.2 billion in Italy, with thousands of acres of land devoted to Roma, San Marzano, and other varieties. They crossed the Atlantic with immigrants, and recolonized the New World in the form of Sunday gravy.

In his new book, “Pomodoro! A History of the Tomato in Italy,” Gentilcore traces the tomato from its origins in the New World, where it was domesticated by the Maya, then cultivated by the Aztecs. It likely entered Europe via Spain, after conquistador Hernan Cortes’s conquest of Mexico. When it arrived on the scene in Italy, it was strictly a curiosity for those who studied plants — not something anyone faint of heart would consider eating. In 1628, Paduan physician Giovanni Domenico Sala called tomatoes “strange and horrible things” in a discussion that included the consumption of locusts, crickets, and worms. When people ate tomatoes, it was as a novelty. “People were curious about new foods, the way gourmets are today with new combinations and new uses of high technology in preparation,” Gentilcore said. Yesterday’s tomato is today’s molecular gastronomy.

Without the tomato, pizza would be bread and cheese, spaghetti would seem naked. The North End without red sauce? Impossible. But the tomato’s role in Italian food is fairly recent, according to David Gentilcore, a professor of early modern history at the University of Leicester in the United Kingdom.

August in New England is the height of tomato season, when fat red beefsteaks, purple and green heirlooms, and tiny, sweet Sungolds beckon at the farmers market. They’re wonderful in crisp salads, as refreshing gazpachos, and all on their own. Perhaps most of all, tomatoes are synonymous with Italian cuisine.

IDEAS: Why was the tomato initially regarded with such horror?

GENTILCORE: The tomato was associated with the eggplant, which was regarded with suspicion. It’s a vine. Anything that grows along the ground was seen as a plant of low status, something you only give to peasants. And the tomato was thought to hinder digestion because it was cold and watery. When ideas about digestion changed, something like a tomato was not harmful anymore.

IDEAS: It’s been called the “love apple.” Was it seen as an aphrodisiac?

GENTILCORE: Francisco Hernandez, a personal physician to King Philip II of Spain, was sent to the New World to write a huge compendium on animals and plants. He was dismayed and disgusted by the appearance of the tomatillo, which was considered the same thing. He compared it to female genitalia. If we look at what constitutes an aphrodisiac in that period, there’s no way the tomato could’ve made it. Foods then were classified by qualities — “cold,” “wet,” “hot,” “dry.” Aphrodisiac food is usually classified as hot and moist and nourishing. Tomatoes were viewed as cold and moist.

IDEAS: Would an aphrodisiac at the time have been considered a good thing or a bad thing?

GENTILCORE: The medical advice was to stay away from these things. In some cases, it made them all the more attractive. Truffles, for example. For the elites who could afford them, that was part of their attraction. Practically all fruits and vegetables were considered harmful. Melons in particular were really dangerous. The only way to eat something cold and moist like melon was to wrap it in prosciutto or ham, which is hot and dry. It was a way of balancing the food.

IDEAS: What explains the tomato’s rise?

GENTILCORE: Tomatoes took off in Italy because they became an industry, mostly for export. Italians were too poor to buy such things. Most of the country’s processed tomatoes are exported. In Italy, up until the 1950s, there was a large part of the country, even where they produce tomatoes, where they wouldn’t eat the stuff.

IDEAS: What about ketchup? It’s such an American foodstuff.

GENTILCORE: When they started making ketchup in Italy, they didn’t call it that. It was the time of Fascism, so they couldn’t use anything with American overtones. They called it “salsa rubra.” They tried to give it an Italian-sounding name. On a worldwide level, most tomato paste these days probably ends up in ketchup.

IDEAS: Last year a tomato blight hit the United States. What if that happened in Italy?

GENTILCORE: I wouldn’t say it would be a national disaster. So much of what goes into cans in Italy anyway is imported tomatoes. You can have tomatoes from, say, Turkey, imported in an unfinished state, half-processed. This is supposed to be done away with, with new labeling legislation, but I don’t know if it has been.

IDEAS: So the great Italian tomato industry is in some sense really the great Italian canning industry?

GENTILCORE: The fact is that Italy exports more tomatoes than it produces. It’s got to be coming from somewhere. The sums don’t add up. China is also a source of imports, or at least it was. Nowadays the can will specify “sourced from Italian tomatoes,” and you have to trust it. Italians are very keen to buy Italian. They don’t want to buy from Turkey, much less China.

IDEAS: Thus San Marzano tomatoes aren’t just delicious, they’re a matter of national pride.

GENTILCORE: It’s seen as one of these great local southern Italian varieties. But this variety was developed for export. The San Marzano variety was essentially created for the British market, but today to say something like that is tantamount to heresy.

IDEAS: Next thing you’ll be telling me Italians are eating those horrible, pale, golf ball tomatoes we get in the United States in the winter.

GENTILCORE: We are starting to get those in Italy. There’s a demand to eat tomatoes year round. These make money. In July, August, and September, the problem is tomatoes are a cutthroat business. If it weren’t for subsidies, I don’t know what farmers would do. In winter, it’s more of a big business. The Mafia has infiltrated the distribution, especially in the shipping or trucking.

IDEAS: Where do the winter tomatoes come from?

GENTILCORE: The Netherlands. They’re the ones who masterminded this whole technology for growing tomatoes under glass. These tunnels stretch for miles. The vines stretch for 15 meters. They’re absolutely enormous. There’s even a special breed of bee that pollinates these plants which doesn’t exist in the wild. It’s a strange, futuristic world being harvested mechanically. If we really wanted traditional tomatoes with very rich flavors, we’d have to be prepared to pay a lot more than we do.

dfirst@globe.com.

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