October 1, 1999

21 Min Read
Pasta Sauces

Pasta Sauces
October 1999 -- Applications

By: Paula Frank
Technical Editor

  Those who find that icing makes the cake might also agree that sauce provides the crowning glory to the pasta dish. Sauces not only contribute visual appeal to pasta, but supply distinctive flavor and texture as well.

  The product designer is faced with the difficult challenge of creating a sauce on an industrial level that looks, tastes and performs like it was made on a stove. "We call what we do a culinary science," says Bob Seeds, president, CF Chefs, Inc., (formerly Country Flavor, Inc.), Dallas. Developing such a product can be accomplished by clearly defining criteria such as processing parameters, pH, storage conditions, ingredient restrictions and, of course, flavor and texture.

"Kling-on" alert

  One of the most crucial elements of a sauce is its stabilizer system. In most sauces, the primary stabilizer will be starch, usually corn starch. While choosing an appropriate starch can be difficult, this can be substantially simplified by knowing critical project and product parameters. These include pH, shear and temperature severity during processing; storage and distribution conditions; finished sauce clarity and sheen; and whether or not the sauce will be high-fat or low-fat. Another consideration is whether the pasta dish will be cooked and consumed in its entirety, or refrigerated and reheated.

  Before the age of microwaves, boxed pasta dinners used unmodified starch, because the products were typically consumed at once. Now, boxed dinners such as mac-and-cheese use modified starches to make leftovers more palatable. "Unmodified starch and the starch that comes off the pasta has a tendency to set back and become very pasty and gummy," says Celeste Sullivan, senior applications scientist, Grain Processing Corporation, Muscatine, IA.

  Modification of native corn starch produces a variety of products that stabilize and viscosify under the harshest of conditions. One modification, called cross-linking, comes from reacting native starch with sodium trimetaphosphate or phosphoryl chloride to produce distarch phosphate esters. Cross-linking confers low-pH tolerance, as well as heat and shear stability, all of which allow sauce formulations to be made with tomato, yogurt or different types of dairy products, explains Sullivan. A cross-linked starch also functions well in a retort application, because the reduced swelling rate of its granules allows for rapid heat transfer, which is critical to the sterilization process.

  Stabilization, another modification, is achieved through chemical reactions such as etherification or esterification. This results in a stronger starch that resists intermolecular associations, as well as the tendency to form a gel and precipitate out of solution. Stabilization, also referred to as substitution, provides freeze/thaw or long-term refrigeration stability and paste clarity. "Most, if not all, starches that are used in the food industry are a dual modification, both cross-linked and substituted," notes Sullivan. Thus, the starch provides not only resistance to heat, shear and acid abuse, but freeze/thaw stability as well.

  After selecting the right starch, other factors, such as percent usage and order of ingredient addition, can be considered. Although a recommended starting level for starch in a finished sauce is generally 2% to 3%, the range may vary from 1% to greater than 4%, depending on the viscosity and mouthfeel desired, and on the percent solids. A tomato-based sauce demands a lower percentage of starch because of its inherent solids; therefore, approximately 1% starch might be used to enhance stability and maintain body throughout shelf life, says Sullivan.

  Combining two different starches in a sauce can deliver the desired cling to the pasta. The primary starch provides stability and viscosity, while the secondary starch is used at a lower level. According to Sullivan, overprocessing the secondary starch causes some degree of setback to occur, therefore enhancing cling.

  For optimal hydration, hydrate the starch with other ingredients that will not compete for water. If water is tied up in a high-solids system or with other hydrocolloids, insufficient hydration causes problems such as setback, syneresis, breakdown in freeze/thaw stability and viscosity loss. Fat tends to coat the starch and make it difficult to hydrate. Hydration of a starch is critical to its performance, particularly when the sauce will be frozen. "Freezing is probably the most stressful thing that you can do to a starch, and that's why it's so very important to have that moisture bound within the starch," notes Sullivan. "So, you need proper hydration; if there is moisture that's available to move in that system, the moisture migration acts almost like razor blades, and has a tendency to rupture the starch granules."

  Selecting a starch only on the basis of process requirements might result in overlooking potential hazards that the product may encounter in the distribution channel. For instance, a cross-linked starch protects a sauce from heat, shear and acid; however, it would not prevent starch breakdown if the product is inadvertently frozen.

  The same starch should not necessarily be used for sauces that will be packed in multiple-sized containers. A hot-filled tote will certainly hold its heat for a longer period of time than will a small jar. Thus, the sauce in the tote will require a more heat-stable starch. This would have a higher degree of cross-linking, and could theoretically be used for both pack sizes; however, processing parameters might require adjustment to account for the higher level of modification. The time and temperature required to fully hydrolyze the starch may differ according to the degree of modification. The time/temperature relationship is crucial to the performance of the starch. "Most always, I would say 80% to 90% of the time, starch granules are undercooked as opposed to overcooked, and I think it is because most of the manufacturers today have goof-proof starches, if you will, where they are designed to be abused more than expected," says Sullivan.

By gum

  Starches can be used in combination with gums for a pasta-sauce application. Xanthan gum is widely used in sauces, because of its unique ability to remain stable in conditions of high heat and acid, as long as the pH remains above 3.0. A too-acidic matrix cleaves the glycosidic linkage of the polysaccharide, resulting in a loss of viscosity, explains Florian Ward, Ph.D., vice president research and development, TIC Gums, Inc., Belcamp, MD.

  Combining xanthan and guar gums gives a synergistic effect. Guar is a very cost-effective thickener, and "you get almost double the viscosity compared to what you have with them alone at the same gum level," says Ward. In addition, guar and xanthan gums exhibit pseudoplasticity, or shear-thinning, properties. They actually lose their viscosity under shear, but regain it when the shear is removed. Pseudoplasticity enables the sauce to be both pourable and pumpable.

  A small amount of carrageenan hinders protein separation in dairy-based sauces. Carrageenan, a negatively charged galacto-sulfate polymer, reacts with casein to form a gel, explains Ward. This, in turn, prevents protein denaturation. This gel structure maintains a uniform distribution of particles in suspension. Using carrageenan in conjunction with guar, or guar and xanthan, provides stability and cost effectiveness.

  Sodium alginate functions with Ca2+ to form a heat-irreversible gel. An appropriate use for sodium alginate would be in a dairy-based sauce, such as alfredo, that is sold in the refrigerated section. Since it forms a nonmelting gel, the sauce maintains viscosity upon reheating. This gum is not acid-stable, and requires the Ca2+ ion to function.

  Propylene glycol alginate (PGA) and gum acacia act as emulsifiers in an oil-in-water sauce. A combination of xanthan/guar for thickening and gum acacia or PGA for emulsifying forms an effective stabilizer system for an emulsion-based sauce, and effectively prevents the fat from separating out.

  Certain gums not only build emulsion stability, but are excellent water binders, which is critical to freeze/thaw stability. "If you add gums to the sauce, it binds (water) and makes it more intact. We actually measured the water-binding capacity of guar gum, and it can be as much as 70 grams of water per gram of guar gum," notes Ward. "The gum actually retards the ice-crystal formation, and might affect the glass transition temperature, which is the temperature below which the water becomes immobile in the product."

  As with starches, the percent usage and order in which ingredients are added significantly impact the success of the gum system. Generally, as a stand-alone thickener, 1.0% in finished product makes a good starting point. However, a level of 0.5% may be more appropriate if gums are used in conjunction with modified food starch. In this case, gums provide viscosity and stability, but, unlike starch, contribute little solids.

  Gums, like starches, need to be hydrated properly. This shouldn't be an issue, as long as ingredients are added in the proper sequence. As Ward explains, "proteins and salt will delay the hydration of the gum. If you put salt in there, the gum will slowly hydrate. Instead of the hydrogen bonds being formed between the water and the gum, the salt, which is more hydrophilic, will hydrate first, and then the water will no longer be available for hydrogen bonding."

  A sauce's texture and capacity to cling to pasta can impact its acceptability. A combination of xanthan and guar gum contributes to both properties. Xanthan alone would form globs, says Ward, but in combination with guar, a smoother texture develops. Using a gel former such as carrageenan or locust bean gum with a thickener such as guar gum creates a very short texture. Also, since guar gum is not heat-stable, cling can be achieved by combining it with xanthan gum, which retains viscosity when hot.

  Emulsifiers can add stability to a sauce, especially when it contains a high percentage of fat. Mono- and diglycerides or phosphate salts may be necessary to prevent fat from settling on the sauce's surface. Lecithin is commonly used in emulsion-based sauces as well. Shelf-life or steam-table stability studies would indicate whether or not additional emulsification support is needed.

ToMato or not toMato

  While tomato-based pasta sauces are identified with Italian cuisines, tomatoes are native to the Americas. Europeans didn't see them until the 16th century. Now they are synonymous with the foods of Mediterranean countries such as Spain, Portugal and Italy.

  In addition to good taste, tomatoes contribute to good nutrition. Not only are they a good source of vitamin A and high in vitamin C, but recent studies have determined that the carotenoid lycopene can contribute to a decreased risk of prostate cancer, and might also reduce the risk of developing colon, rectal and stomach cancers. Ongoing research also suggests that lycopene might reduce the risk of macular degenerative disease, serum lipid oxidation and other cancers. Cooking tomatoes changes the form of lycopene to one that is more easily absorbed by the body. A recent study showed that lycopene is absorbed 2.5 times better from tomato paste than from fresh tomatoes. Lycopene can be found at levels of 42.2 mg/100 grams in tomato paste and 14.1 mg/100 grams in tomato sauce.

  While over 1,000 established varieties exist in the United States, certain types of tomatoes are grown for slicing, canning, paste and sauce. These are usually oval-shaped, and contain fewer seeds and more pulp. When a processing tomato is fresh, it contains somewhere in the vicinity of 5.0% to over 5.5% solids. Most commercial tomato pastes have a solids content of approximately 31% soluble solids, but pastes can range in solids content from 24.0% (light concentration) to over 39.3% (extra heavy concentration) as defined by the USDA grades for canned tomato paste. The pH of most tomato ingredients is approximately 4.0 ±0.3, but can vary depending on the raw material and customer requirements. Most of the acidity of a tomato-based sauce comes from the tomatoes, but citric acid can be used to reduce the pH.

  Tomatoes can be processed as either hot-break or cold-break products. The hot-break process inactivates the naturally occurring pectinase, yielding a higher pectin content. This results in a higher viscosity. By contrast, cold-break tomato products are thinner, because the pectinase remains active. After the product reaches the required viscosity, the tomato is processed into its final form.

  Tomato paste is widely used, but other varieties are also available. Tomato sauce is a smooth, concentrated tomato product that can contain nutritive sweeteners, vinegars and vegetable flavoring ingredients such as onion and garlic. According to USDA standards, the refractive index of the tomato sauce at 20°C must not be less than 1.3455. Slices, dices and other sizes of tomato pieces are also available, and are typically specified by screen size and drained weights. These would be used in a chunky or home-style sauce to provide tomato particle identity. Most tomato pieces will be treated with calcium chloride to maintain a firmer texture.

  Tomato ingredients can be canned or aseptically packed. Commercial aseptic packs range from brick-style liter packs to over 1-ton bag-in-boxes or totes. Aseptic systems use a HTST process that helps maintain particulate and color integrity.

  Tomato solids can also come from a dried-tomato powder that is reconstituted with water. Most tomato powder is spray-dried, usually at high temperatures. A cold-spray-dry-process powder is available that has a higher bulk density and less heat damage to color and flavor. Tomato powder can duplicate tomato paste flavor and color, but it might have some subtle textural differences. "You do get pulpiness from the spray-dried (tomato), but texture and viscosity can be further customized to meet necessary requirements of the final product," explains Dennis Gronfor, director of research for the cheese, dairy, and emerging technology area, Kerry Ingredients, Beloit, WI.

  Although tomato powder is virtually a dried version of paste, and a bit more costly, a powder has several advantages. Powder can provide benefits in inventory storage, and processors are not always equipped to handle paste.

Added touches

  While certain ingredients can add flavor and texture to a sauce, others can enrich the sauce and balance the overall flavor. "If you go back and pull out a French cookbook, you will always find that the classic tomato sauces that were made as part of the mother sauces, were made with roux," explains Bill Schoenleb, C.E.C., CF Chefs, Inc. He continues: "Roux does some wonderful things in tomato products where you're looking for that stewed flavor, and you've cooked it all day, and you're looking for that mellowing effect on acids." Rouxs vary in degree of carmelization, and are themselves combinations of flour and fat from a variety of sources. A highly carmelized roux, such as an español type, can make an average tomato sauce taste as if it was prepared in the back of a kitchen.

  Tomato-based pasta sauces can be quite versatile as determined by the ingredients added to complement the tomato flavor. As long as the pH stays out of the isoelectric range of 5.0 and below, you can add dairy-based ingredients; however, if the acidity is too high, the proteins will precipitate, notes Gronfor. He adds that grated Parmesan is often used, even in acidic tomato-based systems. Although the protein will denature to some extent, the cheese is already separated by the nature of the grating process. The resulting gritty texture is not necessarily an undesirable trait.

You gouda love it

  The flavors and textures of cheese sauces vary widely. These differences are further enhanced by the extensive range of cheese and dairy ingredients. The vast number of ingredients results from not only the variety of existing cheeses, but also from the form, including natural shredded or grated cheeses, enzyme-modified cheeses (EMCs), dehydrated cheese powders, and flavors. Cheese varieties include Cheddar, Parmesan, Romano, feta, fontina and Swiss, as well as many others. The selection can be made simpler by providing the ingredient supplier with key information such as flavor profile desired, cost, form (liquid vs. dry), processing method, and any other relevant information.

  When selecting a cheese ingredient for a pasta sauce, consider flavor first, says Gronfor. "We know if someone is doing an adult mac-and-cheese versus a children's mac-and-cheese, we're going to look at an entirely different flavor profile. There are even some regional differences in what people do with flavors of Italian cheeses. Some people purposely make their products a little bit what we would consider on the mild side, versus others where some are very strong, very pungent."

  Flavor may be the first consideration in choosing a cheese ingredient, but color can also be a factor, since cheese powders often contribute to the color of the finished sauce.

  A segment of the industry uses pre-made sauces as an ingredient in a cheese-based pasta sauce. This provides several advantages, explains Jennifer Gusse, director of marketing, Amboy Specialty Foods Company, a subsidiary of Dean Foods, Rosemont, IL."(A pre-made sauce is) shelf-stable; it eliminates a food processor's need to inventory the quantities of multiple ingredients that they would need to do their own in-house sauce. It controls labor costs, provides consistency of the sauces from batch to batch, and it just adds another level of control."

  Some processors offer complete flavor systems. For instance, a mac-and-cheese flavor system might contain dairy-flavor components such as cheese powders, whey, buttermilk powder or perhaps butter powder, in addition to a stabilizer system containing starches, gums or possibly flour, plus other incidental ingredients and fillers. A complete system like this offers the same advantages as a pre-made sauce.

  A processor making its own cheese sauce often uses other dairy ingredients in combination with cheese to develop a complete flavor profile. As Gronfor explains, "whey is an excellent carrier of flavor. A lot of times, whey will contribute dairy flavors itself, but it is very compatible with the cheese." He also suggests that dairy ingredients not only provide flavor and functionality in terms of creaminess and mouthfeel to the cheese sauce, but carry positive connotations with consumers as well.

  EMCs are another dairy ingredient that can give added value when used at low levels. They can be used in combination with other cheese flavors to produce unique flavor profiles with reduced solids, particularly in higher-acid formulations where the risk of solids precipitation is great. EMCs are recommended for stronger-flavored cheese sauces, because the bitter, soapy notes often attributed to them could be detected in a delicately flavored system.

  Cheese powder is used at a range of approximately 10% to 40% of a dry formula, but this varies dramatically depending on cost and the cheese solids desired. Some use a high level of a low-cheese-solids powder, while others use a low percentage of powder with a high cheese-solids level. The level of cheese solids in a spray-dried cheese powder can range from 10% to 95%. Typically, the lower the cheese solids, the lower the cost of the powder.

  Cheese sauces can be adversely affected by processing conditions if ingredients are not selected wisely. According to Gusse, aseptic cheese sauces are not appropriate for retort processing because the sauce has already been cooked. A second cooking process can result in discoloration of the sauce and overcooked flavor notes. Pat Mugan, director of R&D, Sartori Foods, Plymouth, WI, recommends using a more flavorful product like a Parmesan or Romano in a retort process. In spite of the long high-heat cook process, the sealed container retains the cheese's volatile flavors. The bolder cheese flavors give nice flavor profiles as a result of the captive environment, explains Mugan. On the other hand, hot-filled products will experience more flavor volatization, because of the open environment.

  Cooking in a steam-jacketed kettle offers yet another potential risk to cheese flavors. Mugan suggests that aged cheeses perform better in a situation where burn-on might occur. "Generally, if you speak of burn-on in a steam kettle, that is due to protein that is burning on. The protein, or the casein in the native state, will tend to burn on more because it is a larger molecule. But as the cheese is aged out, it will break down, and the amino acids and the short peptides will allow themselves to solubilize with the sauce better. When they are solubilized in the sauce, they will not tend to burn on as much," he explains. A cheese with a higher fat content will promote greater solubility in the sauce, which also lessens the chance of burn-on.

  An aged cheese works better in a frozen application, once again as a result of its solubility in the sauce matrix. Generally speaking, stabilizers such as starches, gums and phosphate salts protect the sauce during freeze/thaw cycling, and prevent fat and protein separation.

Back to basics

  Many companies have chefs on staff that work in conjunction with food scientists to develop a product that tastes homemade, yet is capable of being produced on an industrial scale. Chefs have been helpful in bringing back some very basic fundamentals of classic cooking, such as using a roux as a building block for a sauce, notes Gene Wisakowsky, Ph.D., R.D., L.D., of CF Chefs, Inc.

  Velouté is a stock-based white sauce. The stock can come from chicken, veal or fish. In classic cooking, ingredients such as egg yolks or cream may be added as a thickener. Industrially, chicken fat and flour can form the basis of the roux, and starch can act as a thickener and stabilizer to provide freeze/thaw stability. Dairy flavors and other components can also be added to enrich the flavor and provide additional texture and mouthfeel.

  Traditional white sauces like béchamel are made with a butter-flavored roux in combination with milk. Béchamel then becomes the base for many other sauces. "If you take a basic white or a béchamel-type sauce and you add cheese to it, I think you are getting a different, more complex flavor profile," says Wayne Casper, senior vice president of business development, Sartori Foods. "You are making it a little more interesting; you give it a little more variety, and you are still not quite at an alfredo sauce. I think there is probably a lot of spatial room between your basic white flour-based sauce and a full cheese sauce like alfredo. So, it really comes down to what cheese you add in what quantities to make for some interesting, subtle variations."

  Additional components added to the base, whether it's a tomato, white or cheese base, contribute to the flavor, texture and appearance of the finished product. Spices, seasonings and dried herbs add flavor and visual appeal. Flavors in the form of oil extractions provide the next best thing to fresh herb flavor. In addition, spray-dried or liquid savory flavors add nuances of vegetables or meats to a sauce. Liquid flavors can be water- or oil-soluble. Both water- and oil-soluble flavors can be selected for emulsion-type sauces, whereas oil-soluble flavors would not be appropriate in aqueous systems.

  Some ingredients have flavor-enhancing or masking capabilities, and can mellow acidity. Hydrolyzed vegetable proteins and autolyzed yeast extracts contribute savory notes, and impart an umami effect. Some sauces are cooked with raw meat or vegetables to impart not only flavor, but texture and appearance as well. Corn sweeteners also contribute to the sauce's appearance by delivering gloss and sheen to its surface.

On top of spaghetti

  Although consumers' tastes vary, a large segment of the population tends to gravitate toward certain trends. What then does this segment tell us about the types of pasta sauces they are consuming? Cheddar is still immensely popular, notably among the younger crowd, who are hefty consumers of macaroni-and-cheese products. "Italian cheeses have grown tremendously," notes Gronfor. This category includes Parmesan, Romano and fontina, plus other unusual flavors, such as gorgonzola, and especially asiago. Casper emphasizes that bolder-flavored cheeses such as these are rising in popularity, particularly if they are fresh as opposed to dehydrated. "You go through a drying process and you tend to drive off some of those winelike, fruity, volatile notes and you are left with mainly the savory notes. Fresh cheeses enable the sauce to have a more rounded, full bouquet," says Mugan.

  "What we're getting a lot of requests for are stronger flavors," says Gusse. "We continue to get a lot of inquiries about garlic, some inquiries about roasted flavors, and the customers are looking for interesting combinations of cheeses. It's really flavors that are strong, that are up front, and that are different."

  Tomato-based sauces are experiencing some of the same flavor trends. Roasted flavors are enormously popular, particularly roasted garlic. Multiple cheese flavors are also penetrating the tomato-sauce market. More traditional varieties such as mushroom, pepperoni, and green pepper still occupy the store shelves, but more robust flavors have a strong presence. Using the term "fresh" underscores herb flavors among many varieties of tomato sauce, and larger vegetable chunks are also apparent among several brands. Some products boast of wine or burgundy flavors, suggesting once again that homemade, back-to-basics appeal.

  Much technology has been developed to enable processors to produce pasta sauces en masse that appeal to the average consumer looking for gourmet convenience. Product developers can take advantage of the available stabilizer systems, flavors, colors and fresh ingredients to design the pasta sauce that stands up to harsh processing conditions, storage and distribution, yet tastes like it was simmered for hours over a kitchen stove.

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