“Clarity is often important for beverages designed to quench thirst,” said Kimberlee (K.J.) Burrington, dairy ingredient applications coordinator for the Center for Dairy Research (C.D.R.), University of Wisconsin-Madison. “Water, the original thirst quencher, has high clarity, and thus many beverages use water as the target for clarity.”
Jean Heggie, beverage industry team leader, DuPont Nutrition & Health, St. Louis, concurs.
“Clarity in beverages provides a visual cue for consumers, setting an expectation that the beverage will provide a refreshing experience,” she said.
Clear does not need to be boring, however. Flavor, color and nutrients may transform an ordinary bottle of water into a wonder drink.
“Clear is viewed as being clean, light and pure,” said Joshua Brooks, president, Gum Technology Corp., Tucson, Ariz. “Add vitamins and minerals and you have a clear, functional beverage alternative as you hydrate.”
Because clarity also may come in colors, it is best defined as the lack of turbidity.
“Turbidity is perceived when light passing through a liquid medium is scattered by particles, typically oil droplets, which have a different refractive index than that of pure water,” said Todd Katz, technical marketing and applications with DSM Nutritional Products, Parsippany, N.J.
Turbidity is often measured with a turbidimeter, which provides a reading in nephelometric turbidity units. The lower the number, the less turbidity and the clearer the beverage will be.
“Many traditional nutrients are not completely soluble in water,” said Russ Hazen, raw materials and innovations specialist with Fortitech Premixes, a business unit of DSM Nutritional Products, Schenectady, N.Y. “They can be dispersed into water, but the result is a cloudy or turbid beverage.”
Solubility of added ingredients is the leading consideration when “clear” is the target.
“When formulating a nutrient system for fortified water or other clear beverage application, ingredient forms that have been specifically developed or modified for clarity should be used,” Mr. Hazen said.
For example, recent advancements in processing technology have made it possible to produce particles so small they appear clear in solution. Also, some fat-soluble vitamins are now available in encapsulated versions for use in clear beverages.
“Turbidity can be reduced by decreasing the particle size of added ingredients below the wavelength of light,” Mr. Katz said. “We use a combination of surface-active starch- and protein-based polymers in combination with mechanical forces, such as high-pressure homogenization, to reduce the particle size of nutrients intended for clear beverages.”
In addition to solubility, real or perceived, there are other important factors to consider when selecting ingredients for clear beverages.
“When developing a nutrient premix, we take into consideration the beverage’s production process, composition and even distribution demands,” Mr. Hazen said.
Amanda Higgins, food chemist at Gum Technology, said, “Clear beverages are typically comprised of sugars, flavors, and in some cases, nutrients suspended in water. Add in carbonation or alcohol, and keeping all the components homogeneous can be tricky.”
Hydrocolloids may assist with the suspension of added ingredients.
“Depending on the type of beverage, a very small amount can help create a homogeneous solution,” Ms. Higgins said. “Ingredients such as soy fiber or gum Arabic can be used for their emulsifying characteristics. They work synergistically with clarified xanthan gum, carrageenan, gellan gum or sodium carboxymethyl cellulose to not only help with suspension but also help with mouthfeel and smoothness without creating cloudiness.”
At such low levels, hydrocolloids assist with clarity, but do not necessarily provide any nutritional value in terms of fiber content. Because fiber is a nutrient of concern in the American diet, many beverage manufacturers are attempting to add value and create a point of differentiation through the addition of fiber.
“Many common beverage ingredients, particularly certain nutritional ingredients, are not compatible in beverages that are clear as they impact flavor or viscosity in a way that detracts from the refreshing experience that consumers expect from clear beverages,” Ms. Heggie, of DuPont, said. “This is particularly true of many fiber sources on the market today.”
One fiber ingredient that is suitable for clear beverages is polydextrose.
“When added to beverages, it has no adverse effect on flavor or viscosity,” Ms. Heggie said. “It is highly soluble and can deliver fiber in a beverage that also provides a light, refreshing experience. Polydextrose is also sugar free and provides only one calorie per gram. It is ideal in beverages where fiber for prebiotic digestive health or satiety benefits is desired.” Applications include functional waters, teas and functional fruit-flavored beverages for general health, digestive health or weight management.
Adding fat-soluble vitamins may be tricky, too.
“When typical fat-soluble vitamin E is spray dried, it is cloudy in solution,” said Alice Wilkinson, vice-president of quality and nutritional product development for Watson Inc., West Haven, Conn. “We developed an emulsion-based vitamin E spray dried within a modified starch matrix. When mixed into a solution, it forms a micellar dispersion, producing a clear solution that does not ring. We also have a liquid gel version of the ingredient.”
Al Vega, manager-research and development with Watson, said a micellar dispersion is basically a solution of micelles in a solvent, usually water.
“The micelles are aggregated chemical compounds that have the ability to be hydrophilic or lipophilic,” he said. “In a micellar solution, they are usually in equilibrium with free un-aggregated hydrophilic or lipophilic systems.”
Beta carotene, which is a pro-vitamin source of fat-soluble vitamin A, has long been used as a natural source of orange color. That intense orange color is often accompanied by slight turbidity when it is used in water-based solutions. A number of suppliers now offer reduced-color versions of beta carotene. They provide the nutrition of beta carotene with less color and none of the turbidity associated with the traditional yellow/orange forms of beta-carotene.
“Historically, many naturally derived colors were cloudy due to the fact that they were oil soluble,” said Jessica Jones-Dille, associate director-marketing and business development for Wild Flavors Inc., Erlanger, Ky. “With our proprietary clear emulsion technology, we are able to provide colors such as beta carotene, apo-8-carotenal, paprika and turmeric in clear forms for use in enhanced waters, carbonated soft drinks and other clear beverages.
“Many natural fruit flavors can be produced without color or cloudiness. Citrus flavors can be more challenging, but certainly can be made clear through the use of proprietary technologies.”
Caroline Brons, director of marketing at DSM, said, “Our proprietary technology enables us to offer many nutrients in a form that allows for a crystal clear beverage, something that the traditional form of the nutrient does not allow. For example, regular green tea extract can impart a bitter taste and a brown color in solution. Our version has no impact on color or taste. We also have a 99% pure trans resveratrol that is clear in solution up to 10 milligrams.”
The company developed a prototype enhanced water drink that looks like water and tastes like water, yet it contains three antioxidants: green tea extract, resveratrol and vitamin E.
“We have developed a range of functional ingredient blends specifically for clear beverages,” Ms. Jones-Dille said. “These are clear, but not necessarily colorless. The key is that the system does not introduce cloudiness into the beverage. The systems enable a transparent appearance.”
The antioxidant blend is based on green tea, white tea, rooibos and grapeseed extracts.
“There’s plant sterols, vitamin E and coenzyme Q10 emulsions that support heart health and are clear in a beverage format,” Ms. Jones-Dille added. “For weight management, we offer a blend of fiber, green coffee and green tea extracts, and for energy, a blend of guarana, vitamin B complex and caffeine.”
The power of protein
Sports recovery beverages are often formulated to contain whey proteins, which are well known for their ability to aid in muscle recovery.
“Whey proteins contain the highest amount of the essential amino acids, in particular leucine, a branch-chain amino acid directly linked to muscle protein synthesis,” Ms. Burrington said.
Specifically, whey protein isolate (W.P.I.) is about 11% leucine, making it the best source of all protein ingredients.
“When adding whey proteins to a clear beverage, it is important to choose an ingredient that has less than 1% fat to maintain optimal clarity,” Ms. Burrington said. “Also, the pH of the beverage should be in the range of 3.0 to 3.4 for optimal clarity and heat stability.”
The W.P.I. derived from cheese whey meets the fat requirement. If using a milk-derived whey protein ingredient obtained through the microfiltration of milk, then an ingredient with 70% to 90% protein will contain no fat and provide good clarity.
“As a class, W.P.I. is inherently much clearer in solution than many other protein sources due to its very high solubility and low aggregation,” said Craig Sherwin, director of the protein technology center for Davisco Foods International Inc., Eden Prairie, Minn. “However, there are differences in clarity among W.P.I.s due to very small differences in levels of fat and aggregated protein.”
The company produces a W.P.I. made by a proprietary ion exchange process.
“This provides high clarity because the ion exchange process is particularly selective for non-aggregated protein,” Mr. Sherwin said. “It is extremely low in fat and extremely high in the native whey proteins beta-lactoglobulin and alpha-lactalbumin.”
It also contains 13.1% leucine, which is the highest concentration in the market.
There are many factors to consider when formulating clear beverages with dairy proteins.
“Dairy proteins are sensitive to process temperatures, pH and the ionic environment of beverages,” said Carrie Schroeder, key account manager, Fonterra USA, Rosemont, Ill. “They tend to interact, network and aggregate, which can create cloud. We developed a W.P.I. that prevents this clouding problem in acidic beverages.”
Ms. Burrington recently worked with two entrepreneur U.W.-Madison graduates to create BadgerMax Protein Boost, a protein-rich, clear isotonic beverage made with W.P.I.
“It was important for BadgerMax to have a clean label, so we worked hard to limit the number and types of ingredients and also create a clear, heat-stable product,” Ms. Burrington said. “Being a clean-label product, the beverage required the use of natural colors, which generally come from fruits and vegetables and can behave much differently in a beverage than artificial colorants.”
Through careful color selection, the C.D.R. team was able to develop purple (grape) and red (fruit punch) beverages.
“Each 12-fluid-oz bottle contains 12 grams of protein, a similar ratio to the protein available in milk,” Ms. Burrington said.
Some isolated dairy peptides also allow for clear beverages.
“Our advanced peptide formulation derived from dairy protein maintains clarity when dissolved in water. It contains all 20 amino acids needed for muscle protein synthesis, delivering them in the form of di-peptides and tri-peptides,” said Ms. Brons. “These molecules do not require additional digestion to be absorbed by the body rapidly and are designed for instant delivery to the muscle. Due to its high solubility, thirst-quenching formulations can easily be developed for different sports nutrition concepts, including endurance, recovery, weight gainer or lean muscle mass gainer.”
Dairy proteins also may assist with managing other added ingredients.
“Dairy proteins have good binding and emulsification properties that can help in suspending added ingredients in a beverage,” Ms. Schroeder said. “Because clear often suggests refreshing and non-filling, clear, protein-fortified beverages can deliver essential protein to consumers while meeting their emotional expectations.”
Clearly, there are many ingredient options to maintain clarity in refreshments.