Unlocking the Potential of Dairy Proteins

May 24, 2017 — A good understanding of protein functionality will enable food and beverage formulators to optimize protein use in a wide variety of applications including, beverages, bars, soups, sauces and retorted products. There is a structure-function relationship. Unlocking the potential of dairy proteins requires thoughtful consideration. “The protein type, chemical composition, structure, amino acid profile, sequence of amino acids and hydrophobicity all contribute to protein functionality in the finished product. Ingredient processing will have a dynamic effect on protein performance,” said Hasmukh Patel, Ph.D., Ingredient Solutions Platform, Land O’Lakes, Inc., in his presentation titled, “Milk Protein Ingredients: Functional Properties & How to Maximize Use in Formulating Foods.”

Casein and whey protein have very different structures. Whey proteins are globular proteins in their undenatured state. When heated, they unfold and interact through sulfhydryl groups and are very heat-labile. Variations in processing of whey ingredients can achieve a wide range of final textures in food products. In contrast, casein proteins are colloidal aggregates with limited tertiary and quaternary structure. Their low content of sulphur-containing amino acids in the casein and limited tertiary and quaternary structure means that they are very heat-stable.

Milk proteins contain both casein and whey in a ratio of 80/20. They are highly functional ingredients with excellent solubility and hydration properties, and add little viscosity or water-binding. Performance of dairy protein ingredients will be influenced by many factors including pH of final product; process parameters; added minerals; type and concentration of protein; other components in the formula; and storage conditions. Patel went on and discussed several protein properties.

Solubility is the ability of a protein to go into solution and remain soluble under different processing conditions. Protein ingredients with optimal solubility will minimize defects, such as chalkiness or grittiness; avoid sedimentation and floating particles; and provide desired nutritional and functional benefits, Patel said.

Compared to a number of other protein ingredients, whey protein isolate has excellent solubility over a wide range of pH levels. Factors which affect solubility include reconstitution temperature, mineral content of the water and pH of the solvent. Other formula components, such as sugar, will compete with the protein for solubility. Whey proteins are most soluble in the wide pH range from 3.0-7.0, while milk proteins or casein-based ingredients perform optimally closer to pH 6.7.

Heat stability can be defined as ability to withstand severe heat treatment such as UHT or retort temperatures without coagulation, precipitation, excessive thickening, gelation or viscosity increase. Coffee creamers, soups, sauces, evaporated milk, UHT and retorted beverages, baby formula and shelf-stable products are severely heat treated. Therefore, heat stability of dairy components is an important attribute in such products.

When whey protein solutions are heated, they denature/ unfold, aggregate and interact with each other. When heated at higher protein concentrations (e.g., more than 8-10% protein content), they aggregate and cross-link to form a gel. Additives, such as sugars, phosphate and citrates, can improve heat stability, as can processing adjustments including pre-heating and homogenization.

Emulsification is the ability of two immiscible liquid (e.g., oil and water) to remain in a stable solution. The proteins in milk and the phospholipids that are present in the cream and buttermilk can successfully act at oil/water interfaces to form and stabilize emulsions, thus functioning as clean label emulsifiers, Patel advised.

New developments in dairy ingredient processing are creating additional opportunities for dairy protein use. For example, innovations in membrane technology have allowed dairy manufacturers to produce a wide range of higher value ingredients, such as whey protein concentrates and isolates; milk protein concentrates and isolates; and ingredients rich in specific protein fractions. Native whey is filtered directly from fresh milk and is not a co-product of the cheese-making process. It has a cleaner flavor and better clarity than traditional whey.

Regular milk protein concentrate (MPC) has a ratio of 80/20 casein-to-whey, but suppliers can produce micellar casein with higher ratios of casein-to-whey. These milk protein ingredients have clean flavor and improved heat stability, making them valuable in applications such as retorted meal replacement, nutritional or sports beverages. Carbon dioxide treatment can be used to create MPC with improved functionality, such as better solubility, heat stability and emulsification. These MPC have superior solubility over 180 days of ingredient storage, Patel said.

Patel also explained that milk proteins have different charges at different pH. Using charged membranes, dairy processors can produce pure protein fractions, for example, alpha a-Lactalbumin (up to 97% purity) and ß-Lactoglobulin isolates (up to 87% purity) without use of chromatography. This technology is currently being researched at UW Madison by Professor Etzel.

These newer dairy protein ingredients add to the list of value-added dairy ingredients that can be tailored to the needs of specific end-uses or applications, Patel concluded.

Click on the following link to see this PowerPoint presentation. “Milk Protein Ingredients: Functional Properties & How to Maximize Use in Formulating Foods” was presented at the 2017 Protein Trends & Technologies Seminar’s Technical Program: Formulating with Proteins.  Hasmukh Patel, Ph.D., Senior Principal Scientist and Section Manager, Dairy Foods Research and Development, Land O’Lakes, HPatel@landolakes.com