There's a whole lot of crunching going on. According to the Snack Food Assoc., the 1994 per-capita consumption of snacks in the United States was nearly 22 pounds. A Columbia University study indicates that savory/crunchy products are the most popular snack choices, followed by baked goods and fruit.
While some salty snacks come au naturel, most carry some sort of seasoning - even if it consists of a simple sprinkle of salt. Seasoning can bring out and complement the flavor of the base, or it can make up the bulk of the flavor. Whatever the case, seasoning plays an important role in the flavor and appearance of a salty snack and greatly influences its acceptability.
"Snacks are essentially fun foods," says Jane Schultz, vice president of communications for the Snack Food Assoc. (SFA), Alexandria VA. "Trying to promote snacks based primarily on nutrition merits just doesn't work. An important consideration in choosing snacks is taste."
Since taste sells snacks, designing the right system might be the most important step in the development process. Most people think of snack seasoning as something sprinkled on top of a product, and most snacks manufactured do use a topical system to provide a particular flavor impact. However, a snack food also may contain a seasoning system added directly to the base.
Designing a system for either of these purposes takes some ingenuity to ensure that the finished product delivers the right taste. Choosing the right ingredients requires careful consideration of the process and the finished product.
A prime example of a multi-purpose component is the ingredient that puts the salt in salty snack - sodium chloride, or food-grade salt. In snacks, salt serves two main functions: It provides flavor, and it often acts as a carrier for other flavors.
Salt may act as the only flavoring agent, as in the case of plain, salted potato chips or pretzels. It can get top billing in a flavor added to snacks, such as salt-and-vinegar. But even if salt gets little mention, it still makes a major contribution to the flavor. When used in combination with other flavorants, salt delivers a salty taste and modifies the overall flavor perception.
Salt has traditionally been used as a flavor enhancer. However, according to Paul Breslin, Ph.D., of the Monell Chemical Senses Center, Philadelphia, sodium chloride actually appears to modify the flavor of foods by suppressing the intensity of the other major tastes, especially bitterness. It acts by selectively removing certain notes and, by doing so, enabling certain aspects of the flavor to come through more clearly.
Whatever the exact mechanism, the flavor of salt appeals to the consumer, especially in snack foods. The SFA reports that low-salt or unsalted potato chips comprise less than 2% of potato chip sales. Low or no salt in other categories such as popcorn, corn and tortilla chips also are not as popular as salted versions.
"Low-salt tortilla chips have met with more success than other low-salt snacks because corn carries a stronger taste and fares better when asked to stand alone," notes Schultz.
Low- and no-salt pretzels are the only snack that has experienced a rise in popularity, according to the SFA. That is probably due to their "healthy" connotation, rather than any flavor preference.
In most salty snacks, the salt level averages about 2%. However, that can vary with the type of product, the flavor, regional preferences, and other factors.
If the salt is used internally, in most cases the size and form of the salt border on inconsequential. The salt only needs to be small enough to be evenly dispersed and dissolve in the available water. However, when used as a topping, salt size becomes an important consideration because it influences a number of factors.
- Flavor: The larger the salt crystal, the longer it takes to dissolve in saliva. The salty sensation lingers. A large crystal also produces a different flavor impact than a smaller piece - sharper, with more bite. Large crystals give a textural impact or crunch when bitten, in addition to a strong salt release.
- Appearance: A large salt crystal is easy to see, reinforcing the salty flavor with a visual cue. When salt is applied to pretzel dough, the moisture on the dough might dissolve a very fine particle. After baking, this would form a small ring on the surface that would mar the appearance of the finished pretzel.
- Adhesion: Choosing the right size and shape of salt particle helps ensure maximum adhesion. Ideally, the salt should have maximum surface to cling to the outside of the snack. This concept may vary slightly depending on the specific application and process. For example, a compacted flake salt adheres better than a granular type on a snack cracker.
"In a pretzel salt you are looking for what I call planar cleavage," says Skip Niman, director, quality administration, Cargill Salt Division, Minneapolis. "The crystals break up with nice, flat sides. You get better adhesion because you have more surface area actually in contact with the dough. An irregular surface only gives you contact at certain points."
For low- or reduced-salt products, designers must consider salt's functions other than flavor. Salt may do more than provide taste as it contributes to the sodium figure on the Nutrition Facts panel. Often it serves as a functional ingredient or as a carrier.
No ingredient can fully match sodium chloride. Potassium chloride approaches the salty taste and can supply many of the functional characteristics of sodium chloride. However, it tends to produce a bitter or metallic aftertaste. To minimize this, flavor experts recommend a blend, usually 50:50, of salt and potassium chloride.
Other compounds can substitute an umami or savory taste for saltiness. Often these flavoring agents are used with standard salt levels to enhance other flavors or provide distinctive flavors on their own. These include glutamate-containing compounds such as monosodium glutamate, hydrolyzed yeast, yeast extracts and the nucleotides. Adding appropriate levels of these compounds can enable salt reductions from approximately 25% to 33% without loss of flavor acceptability. However, because they act by enhancing flavors, they may end up enhancing off-flavors unless the correct balance is achieved
While flavor enhancers that contain glutamate enhance flavor, they may not enhance a product's image. The ingestion of glutamate has frequently been implicated in a number of adverse reactions. Consumer groups and media coverage of the controversy has heightened consumer awareness of this concept. However, the stigma attached to the use of MSG and other glutamate-containing ingredients in foods may be on the wane.
This attitude was reinforced by the report on glutamates issued by the Federation of American Societies for Experimental Biology (FASEB) in August of last year. The report confirmed that the consumption of glutamate is safe for the general population and that it produces no long-term effects on human health.
The report did caution that there appears to be a small number of individuals who experience reactions, particularly asthmatics. Three grams per meal appears to be the dose where short-term reactions seem to occur. For that reason glutamate labeling is still under consideration by the Food and Drug Administration. However, rather than singling out glutamate-containing additives such as MSG and autolyzed yeast extract, the entire free glutamate content would be listed, including that which occurs naturally in foods like Parmesan cheese.
Most topically applied seasoning systems require some kind of carrier to ensure proper distribution on the finished product. Using small amounts of a specific ingredient or a liquid flavor make this necessary. Salt is a common carrier for seasoning blends, but other ingredients are often used, including corn syrup solids, maltodextrins, crystalline acids and MSG.
The selection of a specific carrier depends on a number of factors. The most obvious is flavor. This is one reason salt is so often used; it typically is used at high levels to provide the correct flavor. Some carriers such as corn syrup solids may impart a sweet character. This works well in tomato-based or ethnic seasonings such as Caribbean jerk. Sweetness helps modify flavor extremes such as salt, bitterness or acidity.
"We look at the functional requirements of the carrier in terms of flowability and other manufacturing requirements," says Patrick Mitten, director of marking, snacks, Griffith Laboratories U.S.A. Inc., Alsip, IL. "But there are other considerations, as well. Does it bond to the substrate? Does it give it the right look? Granulation plays a big role in that. Many color attributes are driven by the carrier."
When using liquid flavors such as spice oleoresins or essential oils, carriers act as a plating medium. By distributing liquids onto the surface of a crystalline material, they become for all practical considerations a dry flavor. Unless the level of liquid is relatively low, the more surface area a carrier has, the better the flavor distribution will be. Salt products with specialized structures such as dendritic or Alberger types increase the surface area available for plating.
"Salt is always the first choice, but when there is insufficient crystalline material to plate the liquids, we turn to some of the other carriers," advises Phillip Dungey, senior food technologist, Quest International, Hoffman Estates, IL. "If there isn't enough salt, I'll turn to maltodextrin or lactose or a similar ingredient to get the right consistency. You do have to be careful (because) you can get a difference in color depending on how the ingredients are introduced."
For example, a liquid ingredient can be plated onto salt then added directly to a seasoning blend. In other situations, the salt-plated liquid may be premixed with another dry ingredient from the seasoning blend formula before combining it with the remaining ingredients. In each case, the final proportions of ingredients may be the same, but the color of each seasoning blend may differ.
'Tis the seasoning
Salty snacks may be seasoned with a wide variety of flavors and flavoring agents. The most popular flavors tend to fall into two categories: dairy, such as cheese or sour cream; and tomato-based, such as barbecue and salsa. Spices and herbs such as onion and garlic also show up regularly.
According to the American Spice Trade Assoc., the consumption of hot spices - including pepper, mustard and ginger - makes up over 40% of the U.S. spice consumption and those trends are reflected in the seasonings used on snacks. Some varieties appeal to a limited, often regional, market. However, as with salt-and-vinegar-flavored chips, these may evolve into national trends.
"There are a lot of flavor trends that come from ethnic sources," notes Mitten. "There is a lot more diversity. We are seeing a lot of Mediterranean, Caribbean, and Latin American flavor influences. I think we are being led by many of the restaurant trends."
Whatever the flavor, the most important concept is compatibility with the base. Some combinations are easy to figure out - potato chips and dip or tortilla chips and salsa, for example. Cheese seems to go with just about anything, except possibly nuts. But not all cheese seasonings work the same.
"With a dry cheese, the flavor has to be very stable and the product must be designed specifically for spray-dried applications," says Larry Woodford, group manager, Kraft Food Ingredients, Memphis, TN. "Varieties like Monterey jack and mozzarella are not going to make the most flavorful spray-dried products because the flavors are delicate. The best types for this type of application are bleu, Parmesan and Romano."
With cheese powders the flavor also depends on the level of cheese they contain. This is largely a question of economics; higher cheese contents cost more.
"Real cheese can make up as much as 50% of the formula," says Dungey. "You can drastically reduce that level by adding flavors and maltodextrin. Sometimes that's difficult because so many cheese flavors come across as fruity."
Designers also must address ingredient compatibility issues when choosing flavors. Most snacks contain significant levels of oil, so avoiding ingredients that accelerate rancidity makes sense, even though products may turn over rapidly.
"Some spices may cause problems with certain oils," notes Bob Tramontana, director of product design and development, McCormick and Co., Hunt Valley, MD. "For example, ginger can cause a lipase reaction when coconut oil is present."
Oil soluble flavors are the preferred form, according to Dungey, particularly when the snacks are fried. The flavors first must be plated onto a substrate such as salt or maltodextrin.
"If you put a water soluble flavor on a fried chip, you can get bleeding," points out Dungey. "Besides, the usual goal is to keep the moisture content of the finished product as low as possible."
Leveling the application
On average, salty snacks contain approximately 1.5% to 2% salt as a target; and when applied topically, from about 6% to 12% total seasoning. The level depends on several factors: the flavor impact required, the method of application, and the adhesion.
"Often the level is driven by aesthetics," observes Mitten. "A barbecue-flavored chip is visually appealing covered with seasoning. It's not just a matter of flavor."
Manufacturers use a number of systems to apply seasoning. They can apply it to the surface of an unbaked product, as is done with salt for pretzels and snack crackers. Obviously this would not work with most topically applied seasoning blends because flavors would volatilize, and proteins or sugars would undergo heat-induced transformations. They may coat fried or oiled products while the surface oil is still liquid. This usually involves some kind of cascade or tumbler to disperse the seasoning. Another common method uses a liquid spray system to coat the snacks with a slurry of seasoning and oil which also takes place in a tumbler. Because the slurry typically resides in a holding tank, ingredients should resist settling out during the process. For example, a very fine salt particle stays in suspension much better than a flour salt, according to Niman.
For dry application methods two important factors influence the consistency of the seasoning in the finished product: the consistency of the flow of the seasoning, and the degree of adhesion. Many ingredients are subject to moisture pickup and caking, so adding flow agents can help reduce the problem. These include compounds such as sodium silicoaluminate, silica dioxides and magnesium carbonate.
Two limitations govern the use of flow agents. One is the legal limit - less than 2% in the finished product. The other is dusting. Adding low levels of propylene glycol or other wetting agents can reduce dusting problems.
"If you go too far with flow agents, you can make the mix too dusty," points out Tramontana. "If that happens, you can get poor adhesion, especially with low levels of surface oil."
Adhesion depends on the temperature and level of the surface oil, the particle size and shape, and even the condition of the frying oil.
"Every oil has a set point, the temperature when it begins to crystallize," says Wilbur Gould, consultant for the SFA. "But as oil gets old that will change and the salt is not going to adhere as well as it would on fresh oil."
A seasoning mix should be designed so that all of the components are well mixed and so that settling out or "unmixing" is minimized. This depends on the bulk density, size and shape of the particles in the mix, as well as the design of both the mixing and application equipment. Granulation also affects adhesion.
"There are various products used for salting snacks," explains Niman. "In general it depends on the application and what the surface is like. With potato chips where the oil content is 36% to 38% by weight, you can get by with a reasonably coarse product like a 40 by 100 mesh or coarser. That much oil gives you a lot of adhesion. If the salter is removed down the line from the fryer, there will be less liquid oil on the surface and the salt will tend to bounce off rather than sticking. A tortilla chip has much less oil, 18% to 22%, and you need to use a finer salt, like a flour salt."
Minus fat equals trouble
In the snack industry, as in the rest of the food industry, low- and no-fat products continue to emerge. These products are baked or microwaved, or otherwise dehydrated, not fried. Eliminating frying changes the products. The flavor, texture and seasoning systems are different.
"With the low- or no-fat snacks, seasonings and flavorings can be very important because unfortunately some of the low-fat versions by themselves don't deliver the taste," Schultz notes. "On the other hand, many unflavored, baked tortilla chips are positioned as carriers for salsas and chips. The corn base has a very strong flavor and doesn't need to rely as much on seasonings."
The secret to developing products in this category is understanding the differences - mainly in texture and flavor - compared with the full-fat versions.
Many oils provide a characteristic flavor. Although added flavors can contribute missing fried notes, problems still can occur with the flavor perception. Fat alters the flavor release and prolongs its intensity. For this reason, flavor systems developed for traditional snack items rarely taste the same in reduced-fat applications.
Traditional snack food seasonings - especially dairy-based ones like cheese powder - often contain significant amounts of fat. However, depending on the formulation, the fat level of the seasoning may not greatly contribute to the finished product's fat level.
One of the biggest hurdles in developing this type of product is seasoning adhesion. Normally the film of fat that remains on the surface after frying causes the seasoning to stick. With baked products, this film does not exist. Ingredient manufacturers have successfully developed systems that can be applied in a slurry or paste form using gums or starches for adhesion.
"Without an adhesive system, you are only going to get 1% to 4% levels of seasoning to stick to these products," says Mitten.
"We still recommend a low level of oil for flavor improvement," says Florian Ward, director of research and development, TIC Gums Inc., Belcamp, MD. "The oil on the surface of the product also gives it a sheen." Ward suggests a simple system of gum acacia and gum arabic combined with corn syrup solids, or for less sweetness, maltodextrins. The type of gum acacia selected should be a good film former.
"You spray a solution of the gums on at a level of one part for every 10 parts of finished product so you end up with 1% to 2% gum solids," says Ward. "Using hot water reduces the viscosity, especially if the sprayers don't have too much pressure."
Many no-fat adhesive systems require products to be redried to give them an acceptable texture and shelf life. The problem does not lie in the process itself, but in the additional costs required for equipment and installation.
"We find it's best to dry at about 250°F using convection," advises Ward. "If the dryers are in place, it's easy to implement."
Some suppliers have developed alternatives to this type of system. One example isn't a conventional gum ingredient, but consists of a special flavor system and a texture system that are said to improve the flavor and help to take the brittleness out of baked snack products - specifically ones that are corn- and potato-based.
The system contains a low level of fat, but at the application rate - about 3% to 9% - it meets the requirements of many low-fat applications. It also is designed to be applied with conventional oil spray equipment.
Another approach to flavoring baked, and some fried, chips involves adding a flavor system to the product before the heat process. Difficulties arise with this technique for several reasons. Many traditional snack flavors like dairy ones are not heat stable. High-heat processes like baking remove most of the topnotes and reduce the flavor intensity. Sensory characteristics change.
"The timing of the two types of flavors is very different," states Mitten. "Topical flavors give up-front, immediate flavor development. When you use internal flavors, it's much slower and gives you a back-of-the-tongue perception."
Many of the carbohydrate ingredients used in snacks also give a masking effect, so the flavor intensity and balance can change. Adding more flavor in an attempt to compensate raises flavor costs, usually without achieving a flavor match.
One of the most difficult challenges is developing a flavor that withstands high heat, especially in baked products.
"Many flavors are heat stable, but often that means retort stable. That doesn't always mean they withstand baking," says Dungey. "That's an entirely different situation. With the low moistures required for snack products, you've virtually eliminated the aqueous phase. It's been my experience that the lower the moisture, the greater the flavor loss. Not many flavors survive at that 2% range."
Internal flavors and seasonings also can help boost the flavor impact when a product contains topical seasonings. Once the intense topical flavor hit is gone, they help maintain flavor as the product is chewed. This helps extend the flavor of a tasteless or starchy base.
"A dual internal/topical system often gives a superior flavor profile, especially on some low-fat products," says Michael Nelsen, sales and marketing, Firmenich Inc., Princeton, NJ. "Unfortunately, there's danger of people thinking that this is going to be a cure-all for a poorly designed product. Flavors are not tremendously good at masking. Their strength lies in improving and complementing a good base."
No-fat, low-fat or full-fat, the secret to developing a successful snack product is good taste. The answers may be simple or they may be difficult. The object is to make the consumer succumb to that famous challenge: "Betcha can't eat just one."
A Honey of a snack idea
One interesting technique to improve oil-free potato chips was investigated for the National Honey Board by the Food Science and Nutrition Department of California State University, San Luis Obispo. The goal was to use honey to enhance the consumer acceptability of an oil-free potato chip manufactured with a process incorporating microwave energy to drive off the water. The initial chips, made without honey, lacked flavor and color.
Liquid honey, drum-dried honey and a combination of both were made up into a brine in which potato slices were soaked. The brine contained honey levels from 2% to 3% (powdered honey) and 4% to 6% (liquid honey). This improved the color because the honey provided Maillard reaction precursors. The data indicated that a 1:1 ratio of liquid to dry honey gave the best color results. Experimenters also noted an increase in the force required to break the chips soaked in the honey brine -- defined as "crunch." However, when measured with a J.J. Lloyd Texturometer (Lloyd Instruments, Southampton, England), the difference was not found to be statistically significant.