After pizza came to the United States nearly a century ago, it remained predictable for the next 75 years.
But since human beings can't leave well enough alone, around 1980 chefs started pushing the envelope. Seafood, zucchini blossoms, salad greens, wild game and caviar appeared on pizzas in San Francisco and Los Angeles, and customers flocked to eat them.
The birth of gourmet pizza was exciting, said Ed LaDou, the man widely credited with fathering the movement while at Spago.
But even he admits that for every toppings combination that took off, there were plenty that didn't.
"We've tried fruit on pizza, but it doesn't always work well," said LaDou, owner of Caioti Café in Studio City, Calif. "I've tried game on pizzas that tasted good to me, but never really sold well."
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"You just can't take an ingredient and throw it on a pizza and think it's going to be great," said Lagana, who consults with sauce maker Paradise Tomato Kitchens. "You've got all these different flavors to taste — the crust, the toppings, the sauce and the cheese — and they should balance."
Since the tongue senses bitter, salty, sour and sweet flavors, pizza makers must consider how all four react to new flavors.
Perhaps the most difficult component to pair with an unusual topping is pizza sauce, Lagana said. Not only is it made up of many strong flavors, the natural acid in tomatoes challenge nearly every topping to make itself known on the pie.
"Wild mushrooms are popular, but would they work as a topping?" Lagana asked. "I'd say their earthy, smoky flavor is probably going to get drowned out by the acidity. So you'll want a less acidic, less salty sauce to let their flavor come through."
But since no operator wants to amend his core pizza sauce for a single topping, Lagana suggested trying a white sauce, a blend of cheeses such as Asiago or Pecorino-Romano, or no sauce at all.
What about shrimp? Though it goes well in marinara, its natural sweetness can become cloying when next to the sugar in some pizza sauces.
The cleverest cook goes the extra step to find flavors that counterbalance those that appear in conflict. If something seems too sweet, Lagana suggests balancing it out with something salty, savory — or even spicy-hot, via chiles.
"We know that sausage and apple go well together — savory and sweet," Lagana said. "So to amplify that, maybe I'd cut the tomato sauce with some of the fruit flavors that will integrate everything. Just like the sweet and sour flavors in Chinese cooking marry well, try lots of things to find that balance that makes a well-extended flavor overall. That's the goal."