“FUNCTIONAL DIFFERENCES BETWEEN dairy and plant proteins will aﬀect performance in beverage and bar applications,” said Hong Jiang, Wisconsin Center for Dairy Research, in her presentation titled “Characterization of Functional and Sensory Properties of Commercial Food Protein Ingredients.” Jiang and fellow researchers recently characterized the functional and sensory properties of 30 diﬀerent, commercially available dairy and plant protein ingredients.
Dairy proteins that were tested included milk and whey proteins. Plant proteins included potato, pea, soy and rice protein. All ingredients were >75% protein and were hydrated for one hour at room temperature before testing. Functionality tests were performed at the protein’s native pH. Below are key results. Water-holding capacity is the ability of the protein to trap water within a protein’s three-dimensional structure. This property is important for processed meat, soups and sauces, and bakery/pastry. The proteins with the best water-holding capacity were milk, soy and pea.
Viscosity is also a measure of water-holding capacity and demonstrates the flow properties and thickening ability of a protein ingredient. Of the proteins tested, milk and pea protein had the highest viscosity at 10% protein solution.
Heat stability is an important property for beverages. At pH 3, whey proteins had the best heat stability, followed by plant proteins, then milk proteins. Whey protein isolate (WPI) is ideal for clear RTD applications, such as juice, isotonic drinks and protein water. However, not all whey protein ingredients will be clear. Whey protein concentrate (WPC) ingredients contain fat, so they will make beverages cloudy or milky-looking. WPI is the product suitable for clear drinks. Heat stability at pH 7 is important for UHT beverages and other low-acid foods. At neutral pH, the most stable proteins were milk and whey.
Stability in pH 7 beverage: Ten of the proteins were also tested for stability in UHT beverages based on their heat stability results at pH 7. Formulas were standardized to 5% protein; the pH was adjusted to 7; and formulas were processed in a UHT MicroThermics unit at 140°C for three seconds. At day one, all beverages were stable; however, the rice protein had a sandy texture. The color of the beverages varied by protein source. Bitterness increased after heating. Some of the protein beverages became slightly thicker over two weeks’ storage.
Stability in pH 3 beverage: Seven of the proteins were also tested in a high-acid beverage application based on their heat stability results at pH 3. The native whey, WPI and potato protein produced clear beverages. All beverages exhibited some astringency, but the whey protein beverages had a cleaner and more acceptable flavor profile. Three of the four plant beverages separated during storage.
Emulsion activity is important for salad dressing and coffee creamer. Whey, milk, pea and soy protein were better at forming an emulsion than potato and rice protein. Emulsion stability was measured after heating to 80°C for 30 minutes. Milk, soy and pea proteins exhibited good emulsion stability.
Foaming ability is important for mousse, cake and whipped topping. Whey proteins had excellent foaming ability. Whey proteins also had good foam stability as measured after sitting for 30 minutes.
Gelation ability and gel strength are very important for cake, pie filling and processed meat. Heat is required to induce gelation of protein ingredients. Only 12 of the 30 ingredients tested were able to form a gel. All whey ingredients formed a gel.
Sensory properties in 10% hydrated solutions were determined by a trained panel of nine individuals using an established sensory language. Plant proteins had higher intensity of astringent, bitter, sour and beany flavor than dairy proteins. (Research done by Dr. MaryAnne Drake at North Carolina State University.)
Model protein bar. All 30 protein samples were tested in a typical bar formula. The ratio of carbohydrate/protein/fat was 40/30/30. The bars were stored at room temp or in a 45°C incubator for 90 days. Following room temperature storage, all protein bars were darker in color.
On day one, all protein bars appeared soft. After three months of storage, the milk and plant protein bars became significantly harder than the whey protein bars. After 90 days of storage at elevated temperatures, almost all bars reached an unacceptable level of hardness. Some of the whey protein bars remained comparatively softer. Rice protein bars retained softness during storage but tasted grainy and sandy.
All proteins are unique. Dairy proteins offer a comprehensive solution to end-users compared to plant proteins. When selecting a protein ingredient, remember to choose a suitable functional test for the desired end-use application and manufacturing process.
“Characterization of Functional and Sensory Properties of Commercial Food Protein Ingredients,” Hong Jiang, MSc, Research Specialist, Center for Dairy Research, University of Wisconsin-Madison
This presentation was given at the 2019 Protein Trends & Technologies Seminar. To download free presentations and the Post-conference summary of this event, go to https://globalfoodforums.com/store/protein-seminars/
See past and future Protein Trends & Technologies Seminars at https://globalfoodforums.com/store/protein-seminars/