* This is an excerpt from the Pizza Marketplace special report, "How to Pick a Stone Hearth Oven." Click here to download the report.
Over the past few years, many pizzeria operators have looked back in time to secure their future. As they return to the roots of pizza, they also are getting back to basics in cooking equipment.
For an operator, that may mean making the move to a stone hearth oven.
Cooking in a stone hearth oven imparts a distinctive, easily recognizable taste to pizzas. Such ovens create a unique flavor through their use of an open flame, intense heat and direct contact between the pizza crust and the hearth.
"There's only one way to cook real pizzas to my mind, and that's straight on the deck of the stone hearth oven," said Gareth Bird, who with his wife Sarah operates the Flamin' Nosh restaurant in Stalybridge, Cheshire, England. "No pans, no messing about."
And while the restaurant business is about turning out consistently great food, it's also about entertaining customers. Not only does a stone hearth oven cook a superior pizza, but customers enjoy watching their dinner being cooked by an open flame.
The 10-unit Brixx Pizza chain, based in Charlotte, N.C., uses stone hearth ovens in its restaurants.
"When we design a new restaurant, we strive to make the oven the focal point," said Brixx co-owner Jeff Van Dyke. "It definitely adds an air of theater."
Basic design remains unchanged
Almost since the beginning of civilization, hearth-style ovens were the center of community and family life. Some historians date stone hearth ovens to more than 25,000 years ago.
Made entirely from stone, brick and/or clay, hearth-style ovens featured a flat baking surface, curved walls and a beehive-shaped domed roof. To heat the hearth oven, a wood fire was built in the baking chamber and left to burn for several hours.
Although the building materials and fuels have changed, the basic design of a stone hearth oven has remained essentially the same.
When operators consider investing in a stone hearth oven, two main issues tend to surface. First, ventilation requirements must be addressed.
Although requirements vary depending on the exact style of oven, stone hearth ovens are typically classified as "grease producers" and as such don't have any different ventilation requirements than other kitchen equipment.
Wood-burning ovens may have special ventilation requirements because of the possibility of sparks entering the ventilation duct. Stone hearth oven makers such as Wood Stone Corp. recommend that operators submit ventilation plans with the appropriate authorities before proceeding with the installation of a stone hearth oven.
The second, and most often misunderstood, issue of concern to operators is that of production capability. Stone hearth ovens often carry the mistaken impression that they are low-production pieces of equipment
"In fact, nothing could be further from the truth," Van Dyke said. "We can cook a thin crust pizza in four to five minutes, depending on the temperature of the oven."
It's not the fuel
Some confusion over what role the fuel source plays in the performance of the oven and the quality of the food it produces, but the answer is not what most people expect. The secret of a stone hearth oven isn't in the fuel source, it's in the stone.
Whether you use wood, gas or coal to heat the oven makes no difference for most users of a stone hearth oven.
Originally, oven manufacturer Wood Stone built only wood-fired ovens. However, in 1994 one of the company's customers asked for a gas-fired stone hearth oven, explaining it was prohibitively expensive or impossible to ventilate wood equipment in many prime locations and training chefs to balance a wood fire could be challenging.
A gas oven would allow the company to open in locations previously untenable and standardize their operational training, the client said.
At first, Wood Stone balked at the request, seeing a gas-fired version as a form of oven sacrilege. Officials eventually realized, however, their customers had venting and operational challenges and needed a viable solution.
After spending more than a year experimenting with various oven designs, Wood Stone settled on a dual-temperature gas oven that utilized a radiant gas flame and an underfloor infrared burner. That configuration most accurately duplicated the effects of a wood fire, the company found.
The company ran blind taste tests with food cooked in the new oven design, fully expecting the difference in taste to be immediately apparent. Despite the company's concerns, taste testers could not tell if the food — pizza, bread, meat, seafood or vegetable — was cooked in a gas or wood oven.
The experiment led Wood Stone officials to realize that the flavor imparted by a stone hearth oven didn't come from the use of wood as a fuel source. Instead, it resulted from the intense heat generated by a stone hearth oven and the direct contact between the food and the stone deck.
In a stone hearth oven, as in any other situation where a fire is burning, the smoke rises. In almost all applications, there is no contact between the food and the smoke.
"We discovered the flavor was still there," Wood Stone officials said during their research. "We didn't wake up and realize a flavor had been missing all along, instead we discovered its true source – the stone with an open flame."
The company realized it could achieve the same flavor in an oven with the same core components of open flame and stone hearth regardless of whether the fuel source was gas or wood.
Several of Wood Stone's ovens can burn both gas and wood. Being able to use both fuel sources helps overcome another issue with ovens that strictly burn wood: the length of time it takes to get the oven ready for cooking.
"(Gas-burning capability) allows you to get it up and running quicker and faster," says Waldy Malouf, owner of Beacon Restaurant & Bar in New York. "And then when it's not needed, because you're using not only using wood, you can turn it off."