Whey Protein Puts Functionality in Performance Beverages

by Donna OConnor

Whey protein is a high-quality dairy protein derived from natures purest sourcemilk. It is a complete and rich protein containing all the essential amino acids the body requires for protein synthesis and metabolism. Whey proteins may be concentrated in protein content from 12 percent in sweet whey solids to between 34 percent and 80 percent for whey protein concentrates (WPCs) to 90 percent as whey protein isolates (WPIs). Varying protein contents provide degrees of functional performance and nutritional compatibility. As a rule of thumb, 80 percent to 90 percent whey proteins are used primarily for protein fortification in liquid and dry beverage systems. Various combinations of WPCs and WPIs blends are popular for various functionalities, desired aesthetics and costs.

Many variables and ingredient interactions when formulating with whey proteins affect their functional properties including viscosity, emulsification, gelation, film formation and hydration. They also improve mouthfeel, have rich-bodied texture and can complement the sweetness, flavor, color and appearance (opacity) of the beverage system. These attributes vary in beverages based on the whey protein type, amino acid composition, conformational structure, protein fractions and form.

Whey proteins are soluble over a wide pH range (pH 2 to 10), which is suitable for beverages. Their susceptibility to heat denaturation calls for some caution and careful design in usage. Some whey proteins are not heat-stable due to their globular conformational structure; stabilizers can correct this.

Even though heat denaturation is a concern, that very attribute can be harnessed for maximum beverage stability. The denaturization leaves intact the peptide bonds of the amino acid chains, but changes the globular protein structure. These structural changes affect the proteins solubility and ionic charge. Whey proteins lose solubility near their isoelectric point (IEP), the exact pH in which the protein has no net charge. With no charge repelling each other, the proteins aggregate, gel, flocculate and/or precipitate out of solution. Whey proteins have an IEP of about 3.8 to 5.5, dependent on the whey fractions. Formulators should develop beverages below the pH of 3.8 for the high-acid ready-to-drink beverages (RTDs) or above pH 5.5 close to neutral pH for creamy RTDs.

For high-thermal process conditions, a heat-stable WPC is suited for UHT, aseptic and even retort RTD conditions used for beverages such as adult/child nutritional supplements, meal replacements, disease-specific medical, dietetic/glucose control RTDs, breakfast and infant/toddler formulas. Theses products usually are designed to deliver about 5 g to 16 g protein per serving and enhance the nutritional profile with their valuable array of amino acids. The WPCs also provide a smooth and creamy texture with their lipid (milk fat) fraction that delivers on body and texture. Some protein levels have been noted as high as 20 g to 25 g or more per serving in various sports nutrition, shake-type RTDs.

WPIs are unique in that they are very soluble in high-acid conditions at varying protein levels. In order to achieve a clear, stable protein drink, the formulator must consider pH, thermal process, ionic conditions, acidification and order of ingredient additions. When protein concentrations increase, the pH must go down. When the pH is lowered, tartness and astringency is noted. Different combinations of acids are used to achieve the correct flavor balance.

Agglomerated and instantized whey proteins such as WPC 70/80 along with WPI and even WPH are ideally used for ease of mixability, hydration, dispersion, texture, appearance and taste. Appearance and opacity will vary when using either a WPC, WPI, WPH or blends. Creamers or whiteners are solutions to controlling opacity in beverage mixes if the extra nutrition can fit into the beverage design.

Whey proteins that have been hydrolyzed or predigested offer greater heat stability, increased solubility and reduced heat-induced gelation. Different degrees of hydrolysis will provide different impacts on flavor, functionality, molecular weight and clarity. WPI and WHP blends increase protein quality by delivering amino acids for muscle and body mass maintenance.

Recent protein technology trends concentrate on certain whey proteins to enhance immunity and digestive health. There are indications that some whey proteins can manage blood pressure and have been found to signal satiety in the brain. Whey proteins offer increased mineral levels of calcium, phosphorus and magnesium, along with some vitamins. Ongoing research is even revealing the potential benefits of various whey proteins to beauty management.

The variety of available whey proteins offers many opportunities for enhanced functionality and protein fortification ideas that complement any nutritional design. Manufacturers are continuing to evolve the beverage concept and definition through creativity, innovation and technical expertise by using functional ingredientsincluding proteinsto their formulations.

Donna OConnor is a food scientist consultant to the food and beverage industry. She has been in the R&D area for 26 years developing many commercial products for the retail, medical food, sports and nutrition industries working for major food companies, including Milk Specialties Global, which provided this editorial contribution. Milk Specialties Global Food Solutions , Eden Prairie, MN, is a manufacturer and marketer of specialty proteins for the active nutrition industry. The company offers a wide range of products and application services designed to empower commercial development of healthy consumer options based on their proteins and specialty line of products.