News | November 15, 2000

Beverage Stabilizers

Beverage Stabilizers

By Paula Gerlat
Contributing Editor, Food Product Design Magazine

In the beginning
Juicing up stability
Stabilizing by gum
Weighty matters
Healthy stabilizers
Stabilzers in CSDs
For creamy beverages

Beverage processing became increasingly sophisticated during the 20th century, allowing manufacturers to successfully add nutrients, minerals and herbs without compromising the product's flavor, appearance or texture. The advent of the 21st century spawned the development of a wide variety of drinks to appeal to a wide variety of consumer tastes, from "natural" products to beverages with unique colors and textures never found in nature.

As a result, beverage formulators are now faced with the increasingly difficult challenge of developing new or reformulating old products to suit the latest consumer trends. To accomplish this goal, the selection of appropriate and economical beverage stabilization systems becomes a crucial part of the formulation process. These systems largely depend on the type of beverage formulated, the ingredients used and the desired end product.

In the beginning
Because there are a multitude of beverage stabilizers available to food designers, several questions should be considered: What is the age of the product's target audience? Children will want a sweet, juicy product and will not be as sensitive to viscosity and hazy appearance as adults. However, the adult purchasing the beverage will be aware of the nutrient quality and ingredients, so the stabilizer system becomes important to the production of an acceptable end product.

What are the nutritional expectations of the target audience? Many consumers expect fruit drinks to be high in vitamins, "New Age" beverages are assumed to be made from pure and natural ingredients and health food consumers want health benefits from their beverages. Because of these expectations, ingredients, such as fiber, vitamins and herbs, often are added to beverages sold in health food stores. These factors all influence the type and level of stabilizer needed.

Is the beverage going to be "lite," having reduced sugar and calories? Without sugar's bulk, viscosifying and mouthfeel effects must be supplied by the stabilizer system.

What finished product characteristics, such as clarity or pH, will influence the type of stabilizer needed?

What type of processing, packaging and distribution is the product expected to undergo?

What is the target price of the product? Target price will have a significant influence on the amount and type of juice used in the product, as well as what stabilizers will be required.

Once all of these questions are answered, formulation can begin. After working with various combinations of water, sweetener and juice concentrates to select an appropriate base, or set of bases, the viscosity modifier should be identified next.

Although antioxidants and anti-microbial agents are not considered true stabilizers, they should be considered as part of the formula. Often, extreme conditions encountered during distribution will lead to flavor oxidization or microbial growth.

After a stabilizer system is chosen, other ingredients, such as color and flavor, can be added. These also may require the addition of a stabilizing ingredient to achieve desired finished-product characteristics. Color can give a beverage a more "natural" appearance. For example, orange drinks can be colored with natural colors, such as beta-carotene, or with FDC dyes. But to get the look of a natural juice, often colors can be blended with other ingredients that will act as clouding agents.

Once all of the beverage's ingredients have been decided upon, processing, packaging and storage studies should be run to ensure that the beverage will be stable in the market.

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Juicing up stability
Juice beverages exemplify the changes in technology that allow consumers to enjoy "fresh" juice throughout the year. It also shows why there is an increased need for formulators to use various ingredients and processing techniques to achieve consumer satisfaction.

Until the late 1860s, fermentation was the only means of preserving fruit drinks. Commercial juice production began in 1869, when the Welch Company, now located in Concord, MA, introduced pasteurized bottled
grape juice. During the 1940s and 1950s, new processes, such as flash pasteurization and frozen concentrates, helped make fruit juices an integral part of the American diet. Other processing changes, such as the use of enzymes to increase the yield of juice pressing and ultra-high temperature (UHT) sterilization, allowed for the economical production of "healthy" beverages.

Today, the Nutrition and Labeling Education Act of 1990 (NLEA) requires the percentage of juice in a beverage to be stated above the nutrition panel. For a beverage to be labeled a "fruit juice," it must contain 100% juice. Often, these are blends of juice concentrates combined to produce economical products with traditional tastes.

Most 100% juices will not require carbohydrate stabilizers to supply viscosity. The normal solids content is sufficient. However, in some cases, a stabilizer, such as xanthan gum, is needed to suspend particulate matter such as fruit pulp.

Some juices, such as grapefruit juice, are naturally hazy or cloudy, but juice extraction and processing often removes the natural compounds present in the juices that contribute to haze. Therefore, if a cloudy beverage is desired, a clouding agent, such as certain polysaccharides, proteins, polyphenols, pulp or polyvalent cations, must be added to the juice. Typical polysaccharides used for this application include pectin, starch and gums. Polyphenols are primarily pigments and astringency compounds. Polyvalent cations, such as iron, copper, aluminum and calcium, form insoluble complexes with proteins.

Juice beverages containing less than 100% juice can be called various names including beverage, drink, cocktail, ade or nectar. All of these must state the percent of juice. Most "New Age" beverages contain 5% to 10% juice, lemonades
generally contain 10% to 15% juice, and many health-food beverages contain as much as 80% juice, as well as other ingredients, such as herbs, vitamins or minerals. Some fruit beverages do not contain any fruit juice and must be labeled"fruit-flavored" beverage.

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Stabilizing by gum
Polysaccharides generally reduce flavor impact and should be added to the system before final flavoring is complete. There are many possible products to choose from.

Propylene glycol alginates (PGA), made by esterifying alginates with propylene glycol, are a good hydrocolloid choice for fruit beverages. The ester groups make it harder for the polymer chains to self-associate in the presence of relatively high concentrations of hydrogen and calcium, so they are not as sensitive to calcium ions as sodium and potassium alginate. They are effective in a pH range of 3 to 6 and have emulsifying, stabilization and suspending capability. The degree of esterification (DE) determines each form's viscosity and emulsification levels. The hydrophobic ester groups allow the PGA molecules to associate slightly with the surface of oil droplets dispersed in water, so it sometimes acts as a "secondary" emulsifier. Blends of PGA and xanthan gum have been successfully used in fruit-juice beverages that require particle suspension, calcium fortification and viscosity control.

High methoxyl (HM) pectins make good viscosity-control agents for fruit beverages. They have the advantage of being considered a natural part of many juices. HM pectins have over 50% DE. This refers to the percentage of acid groups present in the pectin molecule as the methyl ester. In a product with levels of less than 55% solids, this pectin acts as a thickener, rather than forming a gel. A dilute pectin solution mimics the viscosity of a 15% sugar solution.

Microcrystalline cellulose, or cellulose gel, and sodium carboxymethyl cellulose, or cellulose gum, are used in beverages as suspending aids, thickeners and stabilizers. These stabilizers are generally considered natural and can provide a source of fiber. Also, they are stable to a pH of 3.0, allowing them to remain functional in most acidic fruit beverages during storage.

The previously mentioned hydrocolloid stabilizers must be fully dispersed and hydrated before they are effective in beverage systems. Often, they can be dispersed using another dry ingredient, such as sugar, as a carrier; addition to a vortex during rapid mixing will disperse the gum. Gum suppliers often suggest making a separate solution of the gum and part of the formula water to ensure complete hydration of the gum. One of the causes of failure during scale-up of a beverage system is improper gum handling.

Also, it is wise to try a scale-up run once the stabilization system is chosen. Often, mixing and heating during processing is quite different from lab or even pilot plant conditions. Because of this, a processing check at this stage will reduce future scale-up problems.

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Weighty matters
Flavors can be either natural or artificial and, depending on the amount of juice in the beverage, they can work as top-notes to add life to the product, or provide the entire flavor to a beverage. Many natural flavors are based on extracted oils from fruit, such as citrus oils, or other oil extracts. For these flavor oils to stay dispersed in the beverage, a weighting agent must be added. Weighting agents are lipophilic compounds with a specific gravity greater than 1.0 that are used to equilibrate the specific gravities of beverage components. Water and water-soluble ingredients have specific gravities of about 1.03, while the flavor oil is usually about 0.87.

To prevent ringing — the colored ring at the top of a beverage caused by the separation of the oil from the beverage — brominated vegetable oil (BVO) has been used to weight the oil. However, in 1970, studies determined that BVOs were possible mutagens and consequently they were disallowed in many countries, including the EU, Japan and Australia. The United States has limited BVO to a maximum of 15 ppm in finished beverages. In most cases, this level is not sufficient to prevent ringing.

Glyceryl esters of wood rosin, also known as ester gums, have also been used for many years in certain countries. They often produce a distinctive rosin-like taste, have low oxidative stability and a slow dissolution rate into flavoring oils.

Sucrose acetate isobutyrate (SAIB) is another weighting agent that has been used for over 25 years in more than 40 different countries. Stephen Byrd, technical service technologist, Eastman Chemical Company, Kingsport, TN, says that SAIB was approved for use in the United States on June 4, 1999 and its maximum allowed use level is 300 ppm in finished beverages. Eastman produces food-grade SAIB by controlled esterification of sucrose with acetic and isobutyric anhydrides. According to Byrd, SAIB is stable to homogenization and to room-temperature storage and makes a very effective weighting agent. Its specific gravity of 1.15 allows greater flexibility than with other weighting agents. It is very safe, does not contribute any off-flavors or odors and is priced competitively with other currently available weighting agents. SAIB can also be combined with glyceryl esters of wood rosin or BVO if the finished beverage requires increased cloud.

If a no-sugar-added version of the beverage is being considered, it's time to consult with the flavor supplier. Many flavors, such as natural flavor oils, are formulated for either sugar or no-sugar-added products. The amount of weighting agent will vary significantly between these two systems and different flavor systems should be used in each.

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Healthy stabilizers
One of the fastest growing segments of the beverage industry is "healthy-lifestyle" beverages. These range from teas to sports drinks to exotic combinations of herbs and vitamins that claim to have health benefits. The benefits of teas are just being explained — they are high in antioxidants and many other beneficial compounds. Isotonic beverages, formulated to restore athletes' depleted minerals, have been available for more than two decades. At first, these were considered special beverages to be consumed by athletes or people suffering with the flu. As part of the healthful-lifestyle attitude adopted by many consumers in the 1990s, these beverages have gained a much wider acceptance by the general public and have paved the way for other healthful-beverages in the general marketplace.

To be accepted by the consumer, these products have to be perceived as natural, taste good and "refreshing," and have an appropriate mouthfeel. Also, like any other beverage, they must be processed and packaged to withstand the rigors of a distribution system. One of the more popular stabilizers, added to teas and other healthy beverages, is HM pectin. Not only does this ingredient add viscosity and stability to the beverage, it also provides a good source of fiber.

Many other beverages combine minerals, herbs, antioxidants and fiber to quell consumers' health concerns. Some of these healthful ingredients can also play a stabilization role. For example, inulin, a natural fiber extracted from many plants and vegetables — most usually commercially extracted from chicory or Jerusalem artichoke — is a natural stabilization ingredient. It has many of the formulation benefits of pectins and cellulose, as well as some unique health benefits. Inulin, a source of fructooligosaccharide (FOS), is fermented in the colon and stimulates the growth of beneficial bacteria. Caution is needed when formulating with this ingredient, because it produces some laxative effects. Therefore maximum use levels must be considered.

Another new fiber source for beverages is FIBREGUM from Colloides Naturels International, Bridgewater, NJ. According to Guido Fetta, national sales manager at the company, the product is 100% vegetable and is processed using physical extraction only — no chemical or enzymatic processing is used. Fetta says that the product is 80% soluble fiber and has probiotic properties without having a laxative effect. The product is available in a water-dispersible, granular form.

Guar can also play a dual role in high-fiber beverages. For example, TIC Gums, Belcamp, MD, offers Nutriloid GuarNT Bland, an all natural, odorless, tasteless form of guar that contributes approximately 80% fiber. This ingredient is both cold- and hot-water soluble, making it an option for instant as well as ready-to-drink beverages. It provides medium viscosity without excessive gumminess, enhances mouthfeel and helps to evenly suspend particulates, such as fine-ground herbs or insoluble nutrients.

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Stabilizers in CSDs
Carbonated soft drinks (CSD) is still the largest segment of the beverage industry and colas are still the leading CSD being consumed. Their long history began in the 1880s, when pharmacists began making mixtures of sugar, citrus and spice extracts in carbonated water and selling them as fountain drinks. Often, these were considered to have some medicinal benefit, such as a hangover cure, but generally, they tasted good and were refreshing. Most pharmacists had their own secret blend and these proprietary blends became the basis for the modern soft-drink bottling industry. The formulator, the pharmacist in this case, sold his extract blend to bottlers in a franchise agreement. This is still generally done today, in a more sophisticated system. The formula owner sells flavor concentrate to franchised bottlers. The bottler then adds water, carbonation, sweetener and preservatives to the concentrate, bottles and distributes the beverage.

Today, the flavor concentrate is more complex than the first blends of extracts. Generally, cola flavors contain mixtures of citrus and spice oils in an emulsion stabilized by either acacia gum (gum arabic) or a specially modified starch. Negatively charged caramel color, kola nut extract and vanilla are also added to the cola flavor. Caramel color has emulsification properties and helps stabilize the flavor emulsion, as well as adds flavor and color to cola.

According to Fetta, the availability and pricing of acacia gum has been stabilized because of an increase in the number of producing countries. Also, the supply and use of non-emulsion-grade seyal acacia has grown over the last 10 years. This allows for a more abundant supply of emulsion-grade Senegal acacia for the beverage industry. Fetta says that there is now a second-generation acacia gum available that is more water-soluble and easier to handle than previous spray-dried materials.

Specially modified starch has also been used to stabilize different types of beverage emulsions, including citrus, cola and others. One such starch is Purity Gum 1773 from National Starch and Chemical Company, Bridgewater, NJ. Himanhu Shah, technical services supervisor, says that a new generation of emulsifying starch was introduced about a year ago. This new starch, Purity Gum 2000, has the same formulation properties of the original starch — cold-water solubility, good viscosity stability and bland taste. Its biggest advantage over the earlier version is that it has long-term, low-temperature stability (up to one to two years) and limited freeze/thaw stability. Shah notes that these starch-based emulsion stabilizers are as functional as gum acacia and typically can be used at lower levels.

Other CSD flavors depend on emulsion stabilizers. Terpene-containing lemon-lime beverages, orange beverages and other citrus-containing beverages require emulsion stabilizers or a weighting agent to ensure that the citrus oils do not separate from the beverage and cause ringing during storage and distribution. As with still beverages, sugar-sweetened or high-intensity sweetener systems will also need different flavor/stabilizer systems.

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For creamy beverages
Ready-to-drink dairy-and soy-based beverages are gaining popularity in the market. Flavored milks, such as chocolate, rely on stabilizers to suspend chocolate particles, improve viscosity and enhance mouthfeel. Also, stabilizers are used as processing aids during HTST or UHT processing.

Carrageenans interact naturally with milk proteins and form permanent suspensions with particulates. They also give these beverages good body to control "glugs" while pouring, without causing gummy or slimy coatings that linger in the mouth. Carrageenan beverage stabilizers are frequently comprised of portions of the three different gum fractions — kappa, iota and lambda — to give the characteristics required by the drink formulator. These are very sensitive to changes in the protein content and make-up of the beverage. If the beverage formula or the type or degree of processing is being changed, contact the carrageenan supplier to ensure that the correct blend is being used.

Low-pH dairy-and-fruit beverages are appearing in the market. These require careful suspending-agent selection because the beverage pH is generally below the isoelectric point of casein, the major protein in milk. Both the correct stabilizer and point of addition needs to be carefully considered early in the formulation process. Often, whey proteins, which are less sensitive to low pH, can be used as a replacement or partial replacement for casein. HM pectins, carrageenans or starches can be used in these systems. Pectin can stabilize acidic juice and milk or soy beverages by complexing with protein. When that protein is exposed to a pH below its isoelectric pH, this complex prevents it from precipitating.

National Starch has introduced a new line of starch-based stabilizers, Textra series, for this application. According to Shah, the company has developed a line of modified tapioca starches that enhances the mouthfeel and texture of liquid foods and beverages, including solutions typically too low in viscosity for starch granules to remain suspended. This type of starch is molecularly dispersed and has excellent freeze/thaw stability. "Attributes such as ease of dispersion, non-sliminess and cost effectiveness make this type of starch a choice of customers compared to other hydrocolloids," says Shah.

Soy proteins and protein isolates have received increased attention since the soy protein/heart health claim was approved in October 1999. Many beverages based on soy isolates with vanilla, chocolate and juice flavors are gaining popularity with mainstream consumers, as well as health-food consumers. Soy-based beverages have increased more than 200% in the past year. The choice of a stabilizer is critical to the acceptability of soy beverages. In order to formulate with soy proteins and isolates, many of the same issues that arise with casein and whey proteins and isolates need to be considered. What kind of protein/stabilizer interaction can be expected? What is the final pH of the beverage? Is this pH compatible with both the isolate and the stabilizer? Will the stabilizer fit into a clean (all natural) label?

There are a variety of reasons for drinking a beverage: appearance, mouthfeel, nutritional content and/or flavor. No matter how different they are, they have many formulation issues in common. Water, the main constituent in all beverages, must be controlled by the use of stabilizers and emulsifiers to manage its interaction with other ingredients. Stabilizing ingredients not only helps beverages maintain quality throughout processing and distribution, but contribute to a good flavor and overall mouthfeel of the end product.

Paula Gerlat received her B.S. in Food Technology from the University of Wisconsin, and has spent more than 30 years in the food industry working as a product developer in both dairy and soft drinks. Throughout her career, she has gained knowledge of processing, QA and distribution problems associated with taking a successful product from bench through scale-up. Paula can be reached via e-mail at paulagerlat

• Photo: FIS-North America

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Used with permission from Food Product Design Magazine

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