Pizza Keeps Rolling On

December 2001

Fresh or frozen, take-out or eat-in, pizza has become a standard in the diets of U.S. consumers. Although they still love their traditional pies, these same consumers also are embracing new pizza configurations and flavor combinations. And while this is a very exciting area in pizza development, product designers need to roll out a proper foundation before reaching for that pie in the sky.

Considered a peasant’s meal in Italy for centuries, the Greeks actually introduced the idea of using bread as a plate. They would take round flat bread and bake it with toppings such as olive oil, garlic and herbs to make plakuntos. The Romans enhanced the dish with a greater of variety of toppings.

Modern pizza is attributed to a baker in Naples, Italy, named Raffaele Esposito. In 1889, Esposito baked pizza especially for a visit from Italian King Umberto I and Queen Margherita. To make the pizza special, he baked it with tomato and basil, which — along with mozzarella cheese — provided a patriotic green, white and red dish. Because the pizza found such favor with the queen, Esposito named it “Pizza Margherita” in her honor. The resulting popularity of this configuration also led it to become the standard for pizzas being created even today.

Italian immigrants introduced pizza to the United States in the 19th century. By the early 20th century, these immigrants began to open their own bakeries and were selling groceries as well as pizza. After World War II, returning U.S. soldiers fueled the nationwide demand for the pizza they had enjoyed while in Italy. This led to a rapid expansion of awareness and popularity for pizza through the 1950s and beyond.

An ideal canvas for creativity, pizza no longer is just flat and round like the original Neapolitan style. The pie varies throughout not only Italy, but Europe as well. Pizza even takes on different toppings and configurations depending on the region of the United States from which it comes. But no matter what toppings are used, or the shape the pizza may take, they all start with a foundation of crust.

Farinaceous footings
Pizza always starts with a flour-based crust, whether it’s baked thick in a pan, or thin and crispy on a sheet. To provide extensibility for rolling and forming, pizza-crust flour typically should have between 11.0% and 14.0% protein. The crisp, firm structure of thin crusts requires flour on the higher end of that protein range. Thick, chewy crusts and crust for deep-dish products need a flour on the lower end of the protein range. Although pizza crust is leavened, it is flat and doesn’t require the gas holding power of white pan-bread dough, so the flour shouldn’t require bleaching.

As with most products that use flour as a structural ingredient, protein content only tells part of the story. The protein quality varies between different wheat types and in different crop years. The final determination of how flour will perform depends on physical analysis and/or bake testing.

The ideal way to determine a flour’s suitability for pizza crust is a bake test, along with analytical tests for moisture and ash. Physical tests on the flour’s rheological properties — such as moisture absorption, mixing time and dough stability — may not be as revealing as an actual bake test, but they have the speed advantage.

Excess water absorption affects both the dough’s machinability as well as the crust’s texture. Flour with high absorption typically contains a high percentage of damaged starch — a common occurrence in the flour-milling process. Not only does damaged starch absorb far more water than undamaged starch; many believe it to be more susceptible to naturally occurring amylases in the dough. Both properties result in a softer dough.

For a crispy, thin crust, try to keep the water absorption range between 50% to 60%. For thick crusts, target a range of 60% to 75%. Remember that optimum moisture levels prevent doughs that are too soft and sticky, or firm and difficult to machine.

Rising from the foundation
Next to flour, the most important pizza-crust ingredients are the leavening agents that provide lift to the crust. This is particularly critical for frozen rising-crust pizzas. Thin crusts typically require very little leavening, but still require an open, smooth structure from leavening agents to acquire proper eating qualities.

The traditional pizza-crust leavening is bakers’ yeast (Saccharomyces cerevisae). As in bread baking, the yeast metabolizes nutrients, such as sugar, and releases carbon dioxide, which is trapped in the flour’s gluten network. Depending on the manufacturing environment, either dry yeast or compressed yeast may be used.

Because cold temperatures do not affect its performance, yeast can be frozen successfully. When frozen as part of a dough, however, the moisture present can freeze into ice crystals that may damage the yeast’s cell walls. Freezing also increases the concentration of solutes in the dough. The resulting increase in osmotic pressure also may destroy yeast cells. For these applications, specify yeast that is specially designed to resist such osmotic changes. In addition to being the traditional leavening, yeast contributes a characteristic flavor, color and texture to pizza crust.

Some pizzas, such as rising-crust varieties, need chemical leavening agents either in addition to, or instead of, yeast. Besides being more resistant to inactivation through freezing, chemical leavening also tends to be faster and more consistent.

Chemical leavening systems produce carbon dioxide either by the reaction of an acid and a base, or by chemical decomposition. Because the chemicals may react any time after water is added to the system, this gas may form at any point in the process from mixing through baking. The type of chemicals used and/or any special fat coatings that prevent reactions from occurring until attaining a certain temperature control the gas-releasing properties of a chemical leavening system. As with yeast, chemical leavening systems directly influence the crust flavor, texture and appearance.

Baking powders consist of finely powdered sodium or potassium bicarbonate, along with an acid salt, such as sodium acid pyrophosphate (SAPP), blended with starch. The starch separates the acid and base particles in order to prevent premature reactions during storage. Producing most of its carbon dioxide during the mixing stage, fast-acting SAPP only produces additional gas at the early stages of the baking process.

Sodium aluminium phosphate (SALP) is slow-acting and generates gas primarily at temperatures above 135° F. This slow onset of carbon dioxide production makes SALP a candidate for crusts that rise in the oven. Glucono-delta-lactone also is a slow-acting acid, but tends to cost more to use than SALP.

Final crust touches
Because yeast must ferment carbohydrates to create carbon dioxide, pizza crust formulas, like most yeast-leavened products, contain low levels of sugars. The most commonly used carbohydrates include sucrose, high-fructose corn syrup and corn syrup, but others may provide specific color and flavor effects. Crust color also may be obtained by adding whey to the formula at 2.0% to 3.0%, based on flour weight.

Traditional handmade pizza often has a brushing of olive oil on the crust surface prior to the application of toppings. This primarily contributes flavor, but also can slow unwanted moisture migration from the sauce and toppings into the crust. The crust also typically contains shortening or oil in the formula. Although olive oil isn’t often used in manufactured pizza crusts, they do contain some added fat to help minimize stickiness and improve machinability. Typical fat levels are between 2.0% and 4.0%. Thin crusts have fat levels on the higher end of this range, while thick crusts only require low levels.

Salt serves two useful functions in pizza crust. First, it helps enhance the flavor. Salt also may help reduce ice- crystal formation in frozen crusts by depressing the freezing point. Because toppings, such as cheese, tomato sauce and certain meats, also contribute salt, the amount in the dough usually is only about 1.0% to 1.5% for thin crusts, and 1.5% to 2.0% for thick crusts.

Another way to enhance the crust’s sensory characteristics is the addition of corn flour (up to 5.0% on a flour basis) or finely ground cornmeal. Based on flour weight, 10% corn meal in thin crusts and 20% in thick crusts will provide color and chewiness without adding toughness.

To help improve machining and post-bake volume, some pizza crusts contain dough conditioners, such as emulsifiers, enzymes, stearoyl lactylates and L-cycsteine. Emulsifiers, such as mono- and diglycerides, interact with starch granules to delay their gelatinization. This keeps the dough more flexible during baking so the crust gains more volume. Protease enzymes hydrolyze flour protein into peptides and amino acids, which makes the dough more elastic so it can achieve greater volume. Pentosenases hydrolyze pentosans, yielding a softer dough that is more resistant to machining. Sodium stearoyl lactylate (SSL) builds volume when used with flour that has a protein range of 11.0% to 12.0%. At 0.25% to 0.50% use levels, SSL improves process tolerance and gas retention for greater volume. L-cysteine is an amino acid that functions as a mix-time reducer. It does so by softening dough when used at levels of 60 to 90 ppm based on flour. For high-speed operations, a shorter mix time can improve the texture of the crust. Dough-conditioner suppliers often can create custom blends specifically designed for a particular pizza application.

A final option for crusts is simply not to bother with formulating one. Suppliers can provide a premade crust, either from stock formulas or custom-developed specific to the customer. Because they’re specialized, bulk crust suppliers claim they can provide greater consistency. In addition to offering a wide selection of formula types — including self-rising crusts — crust suppliers also offer a catalog of dies for their forming equipment to offer several pizza shapes and thicknesses.

Getting into the sauce
The next layer to build after the crust is the sauce. Even more than the crust, the sauce offers an array of potential options for customizing the product. Tomatoes are a primary feature of contemporary pizza — whether they take the form of a tomato slice or a tomato-based sauce. Europeans returning from Peru and Mexico first introduced tomatoes around A.D. 1522. Originally, most Europeans believed them to be poisonous. However, hunger eventually led the people in the lower socio-economic classes to begin adding tomatoes to the top of their pizzas. Eventually, travelers popularized pizza — along with the tomato — across regions and class distinctions.

Water and tomato paste form the base of industrial pizza sauces. Between the tomato solids and added sugars, a sauce’s total solids level typically falls between 15% and 30%. The style of the pizza will dictate the thickness of the sauce and, therefore, where to target the total-solids specification. To reduce sweetness in the sauce, longer-chain maltodextrins also may contribute solids and viscosity in place of some of the sugar. Some industry sources claim they may also enhance the sauces’ red color.

Although the sauce’s total solids level goes a long way toward determining the thickness and body of a sauce, industrial applications often require greater control over viscosity, crust adhesion, ice-crystal formation and freeze/thaw stability. Here, starches and other thickeners come to the rescue.

Because tomato-based sauces provide an acidic environment, pizza sauces typically are thickened with modified starches from dent corn. These tend to have a lower viscosity at higher temperatures, which aids pumping and application during production. The type of starch modification will depend on the applications. A frozen pizza may require a substituted starch for greater freeze/thaw stability, for example. On the other hand, a sauce designated for shelf-stable packaging — such as an in-home pizza kit — may require the acid and heat stability provided by crosslinking.

Bringing in the seasonings
With the solids level and viscosity set, the sauce next requires enhancement with seasonings and other ingredients. Another traditional addition is olive oil. Although it does contribute a distinctive flavor, its presence also helps protect oil-soluble volatiles in the seasonings. A level of 1.5% typically is sufficient to help stabilize these oil-soluble flavoring components.

As with many other traditional Italian dishes, garlic and onions provide an undercurrent for the additional seasonings in a typical pizza sauce. On top of this background usually is the aromatic contribution of basil and/or oregano. As Italian cuisine experienced expanded interest in the U.S. during the 1950s, oregano usually provided the primary characterizing note. Over time, U.S. consumers have embraced the more-traditional flavor of basil as the primary herb. Although many dishes often use both, basil now tends to take the dominant role in the seasoning profile that once was occupied by oregano.

Pizza sauce provides an ideal vehicle for adding other flavorful ingredients in addition to — or, perhaps, in place of — these traditional seasonings. These might include other spices or herbs; mushrooms; and vegetables, such as bell pepper. Although U.S. consumers increasingly favor sauces that are less sweet, sauce formulas often contain low levels of sweeteners to ameliorate the acidity of the tomato.

In an idealized situation, all of these herbs, onions, etc. would be used fresh from the produce distributor. Of course, the scale of most food-processing operations makes this cost prohibitive. For ease of handling, many product designers turn to dehydrated versions. Although these are highly effective ingredients, they often taste different from their fresh counterparts. For some products, frozen herbs may be more suitable for providing a “fresh,” more “upscale,” flavor.

Most dehydrated herbs retain only around 60% of the flavorful volatiles. This may drop to half that after only six months of storage. Starting with nearly a full complement of volatile oils, fresh-frozen herbs will only lose about 7% of them after six months in frozen storage.

A key phrase here is “frozen storage.” The chief disadvantage to frozen herbs is that they require the extra energy and handling costs for frozen storage. In addition, the moisture content of frozen herbs means they must be used at one-and-a-half to twice the weight of their dried counterparts. Furthermore, frozen herbs also tend to be more expensive. The net effect is that frozen herbs must be used judiciously to keep costs in line.

If one doesn’t have carte blanche to use all frozen herbs, use creative combinations. For example, use garlic and onion powder for the background flavors, but select a frozen basil paste to get that fresher flavor in the top notes. Another idea is to incorporate some dried basil into the sauce, but use some individually quick-frozen (IQF) basil pieces as a topping. This not only adds a bit of those fresher flavor notes, but visual interest.

The final shred
With the crust and sauce in place, cheese completes a pizza’s basic structure. U.S. consumers are most familiar with mozzarella as the primary cheese topping. It has a pleasant, mild flavor that melds well with other ingredients and toppings. Mozzarella also has unique melting characteristics that bring the pizza components together as a unified product. As with crust dough, the ingredients and processing method used to make the cheese will significantly affect its flavor and performance and, consequently, the quality of the finished pizza.

Originally made from water-buffalo milk, mozzarella is made from whole or partly skimmed milk blended with starter cultures and acidified by organic acids. Although whole-milk mozzarella has a richer flavor, it tends to release oil during baking, yielding a greasy pizza. Consequently, the part-skim varieties tend to be the best choice for use on pizza.

Next, a rennet extract coagulates the acidified milk into curd. Without cooking, the cheesemaker will cut this curd, form it into blocks and leave it to drain. During whey draining, these blocks are held at elevated temperatures to allow the starter culture to acid-ripen the curd to a pH of 5.2.

Once the correct pH is attained, the curd is heated in hot water, stretched or mixed. This process — shared by both mozzarella and provolone cheeses — encourages the milk proteins to form long chains that give these cheeses their distinct stretching and melting properties. The accompanying heat also inactivates any residual coagulant and reduces the population of the starter cultures. After sufficient mixing, the cheesemaker finally salts the cheese and molds it into forms.

A key quality for pizza mozzarella is shredability, which is controlled by the total moisture content. The USDA sets standards on the amount of milkfat and moisture in certain types of cheese. For low-moisture, part-skim mozzarella, the maximum amount of moisture must lie between 45% and 52%, while the minimum percentage of milkfat in the cheese solids must be between 30% and 45%. This gives the cheese better slicing and shredding properties for pizza than the softer, high-fat mozzarella. Low-moisture cheeses also will be more resistant to freeze/thaw damage.

Adding milk solids also improves mozzarella shred by contributing body to the cheese. This also increases surface browning when the pizza is baked, as do lower fat levels. However, because some consumers prefer the cheese on their pizza to retain its white appearance, determine what the product target should be and specify fat and milk-solid levels accordingly with the cheese supplier.

How the cheese melts is the next key factor in determining what to specify for the pizza. Generally, it’s most desirable for the mozzarella to melt uniformly into a smooth, homogeneous mass with little or no liquid — in the form of water or oil — bleeding onto the surface. Melting characteristics are affected by the starting ingredients, the pH and the degree of proteolysis as the cheese ages.

Typically, using nonfat ingredients with higher moisture will yield more meltability. Melt also improves as the pH is lowered. Ideally, mozzarella should be at a pH 5.25 for the best structure and melting qualities. Too high — say, 5.80 — and the cheese will be too stiff. Too low — around 4.80 — and the cheese will not appear to melt at all.

Although the long protein strands formed when the mozzarella is made give desirable stretch, some of these strands need to be broken down so the cheese isn’t too chewy. As cheese ages, proteolysis occurs, which eases up the stretchiness and improves meltability. Of course, too much aging will take away the mozzarella’s characteristic stringiness, so be sure to determine and specify an appropriate degree of aging.

Cheesy options
Although many consumers (and product designers) consider mozzarella the cheese for pizza, other cheeses can help regionalize a pizza, or simply make it a unique product. Varying the flavor by using Monterey Jack or Cheddar in addition to the mozzarella, for example, can further customize a pizza already made unique by a special crust and custom-formulated sauce. As with mozzarella, though, the cheese selected should have certain qualities in order to maintain the pizza’s integrity.

First of all, any additional cheese should have melting characteristics similar to those of mozzarella. Provolone and Monterey Jack are two examples of cheeses that melt much the same way as mozzarella. Softer cheeses, however, also may be compatible. Small quantities of Brie or feta may melt faster, but they’ll do so evenly, intermingling with the mozzarella and further tying the pizza together, as well as contributing their own flavors.

Another consideration is the cheese’s ability to be shredded or cut into a suitable size and shape. Brick cheese, provolone and Monterey Jack all shred well and can be easily blended with mozzarella prior to application. Harder cheeses, such as Parmesan and Romano, probably are not suitable as shreds for the top of a pizza. They tend to be very firm and not so easy to melt. Finely grated, however, they may contribute additional flavor when added to the crust dough or sauce formula.

In many cases, cheese is a major fat contributor to pizza. Unfortunately, reducing fat often negatively affects the melting characteristics of cheese. In 1999, researchers at Cornell University, Ithaca, NY, discovered how to improve the melting qualities of fat-free or low-fat mozzarella. Rather than include fat in the cheese, the Cornell food scientists applied a thin, invisible, hydrophobic surface coating incorporating canola oil to the cheese. When baked, the modified no- and low-fat mozzarellas behaved like the full-fat counterpart by fusing, browning and blistering in the same way.

In June 2000, Suprema Specialties, Inc., Paterson, NJ, entered into an exclusive agreement with the Department of Food Science at Cornell University to use their research and patent for processed mozzarella cheese. Since then, the company has been developing a commercial version of the processed mozzarella cheese for distribution.

Finishing touches
With the crust, sauce and cheese in place, the basic structure of the pizza now is complete. Delicious as such a pizza may be on it’s own, even more variety and creativity is possible through topping selection. Most of the time, toppings will either be meats, or vegetables, herbs and mushrooms.

Among the meats, sausage and pepperoni rank among the most popular pizza toppings. Following closely are Canadian-style bacon, ground beef, diced chicken, and even seafood, such as shrimp.

Although these items can be prepared and applied in-house, pizza processors are increasingly turning to prepared meats and meat crumbles. A meat supplier will form, cook and individually quick-freeze meat pieces into a uniform ingredient that is easier to scale and apply. This consistency usually is the result of proprietary processing that gives uniformity, but not so much as to make the pizza look too “machine made.” Of an even greater advantage to uniformity is the fact that these ingredients also help minimize microbial concerns in the manufacturing environment since they are precooked, frozen and carry certificates of analysis from the supplier.

In addition to assuring adequate microbial controls with the supplier, product designers also must specify a crumble with the correct fat content. As with cheese, sufficient fat is necessary for desired eating qualities, but it shouldn’t puddle on the surface as the pizza is baked. Although a meat supplier may offer a line of sausage ingredients with different fat contents, it also may be able to provide a customized ingredient. In addition to fat level, other specifications may include color, flavor and piece count per pound.

As with meats, vegetables provide an open door to creativity with pizza toppings. In addition to flavor, vegetables also offer a high level of visual appeal to the pie.

Fresh vegetables are a good choice from a quality standpoint. However washing and cutting vegetables, along with maintaining the equipment to perform this function, adds complexity to the pizza-manufacturing environment that many companies choose to avoid.

As an alternative, many companies look to freeze-dried vegetables, which are easily stored and handled. They also retain their structure, appearance and the majority of their flavor. As with meat crumbles, the product designer can exercise some creativity in the size and cut style of the vegetable. As the name implies, however, toppings are on the top of the pizza and most exposed to the heat of an oven. Consequently, dried vegetable pieces must be rehydrated prior to application.

As with herbs, IQF vegetables tend to retain more flavor than dehydrated versions. They also are often available in more unique varieties, such as roasted peppers. By being frozen individually, such vegetables will be flowable and easily deposited on top of a pizza in their frozen state.

With vegetables serving as a value-added topping, some designers may wish to add significant quantities. When the finished pizza is baked, however, they find water collecting on the surface. This is caused when the vegetables — which typically are around 90% water — break down when baked. Fortunately, the American Institute of Baking offers some guidelines to minimize this problem.
• Specify thinly sliced vegetables. This helps reduce the amount of water remaining on the pizza by allowing moisture in the vegetables to more easily bake off as steam.
• Coat the vegetables in oil to reduce watering out. This is a particularly useful technique for mushrooms.
• Reduce the amount of vegetables, because the amount of water released is proportional to the amount of vegetables used.
• Deposit vegetable toppings on the very top of the pizza, not under any of the cheese. This will prevent the water from being trapped and allow it to bake off.
• Bake the pizzas at a slightly lower temperature, for a slightly longer time. Although this reduces throughput, the extra time allows more water to bake off. If creating an unbaked pie, test for optimum baking time and alter the consumer’s preparation instructions accordingly.
• Use sautéed, grilled or canned vegetable toppings. These toppings do not release as much of their water content during baking.
• When using higher quantities of vegetable toppings, try reducing the amount of sauce. Another option is to increase the sauce’s total solids content above what normally is required. The vegetables will then contribute the extra water during baking.
• If creating prebaked pizzas, use impingement ovens. Here, the focused, high air velocity is more effective at evaporating excess water off of the top surface of the pizza.

From crust to toppings, pizza offers vast opportunities for product creativity. To test the creative potential, Freschetta, a division of Tony’s Pizza Service, Marshall, MN, created the Freschetta Culinary Council. The council brings together five leading chefs to develop new formulas for the company’s pizza brand. The chefs get together every two months to cook together in the kitchen. Since the formation of the Council in January 2000, they have gathered in Minneapolis, San Francisco, Phoenix, Chicago and in Italy, where they collaborated with an Italian pizza master.

The chefs’ first task was to enhance Freschetta’s existing pizza varieties through changes to the sauce, cheeses and toppings, with some slight modifications to the crust. These products were available in stores beginning in March, 2001. Now the Council is introducing the first pizzas that the chefs created together from scratch: a Southwest Chicken Supreme pizza, a Roasted Garlic Chicken pizza, and what Freschetta claims is the first authentic frozen Margherita pizza offered in the United States.

Most companies, however, won’t be able to assemble such an elite council. In fact, product designers likely will find themselves a “council of one” when asked to formulate a new pizza. But with a mind to the basic structure, and an open mind to potential variables in crust, sauce, cheese and toppings, the pizza canvas is ready for the brush-strokes of creative food scientists everywhere.

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