Linking Protein Structure to Function & Applications

Originally Published: December 1, 2015
Last Updated: March 2, 2021
Linking Protein Structure to Function & Applications. Globular proteins, the dominant group of proteins, are compact, folded and generally water soluble.

December 1, 2015—When a food manufacturer decides to fortify a product with protein, they must first determine the target protein level and then develop a narrative story for consumers to believe in the product. If the product is targeted for muscle-building, then the narrative will be different than if the product is targeted for weight management. The narrative builds credibility in the product, its purpose and what it stands for to consumers, said Julie Mann, MSc, Staff Scientist, Snacks and Adjacencies Research, The Hershey Company, in her presentation “The Protein Bridge: Linking Protein Structure to Function & Applications.”

The target level of protein influences whether to fortify with a protein isolate, protein concentrate or whole food protein product. Potential claims might be 5g of protein to make a “good source” of protein claim; 10g to make an “excellent source” claim; or simply “x grams of protein.”

If the protein does not meet protein quality standards (PDCAAS), as is the case with many plant proteins, then several proteins or additional grains may need to be combined to correct for protein quality, said Mann.

When selecting from the vast array of protein ingredients, cost and functionality are critical considerations. Mann explained: “The formulator needs to ask, what functional attributes will the protein provide? Is the ingredient readily available? Will the finished product be cost competitive, and is there price volatility?”

Meeting consumer demand for clean label and sustainability introduces other issues. Can the protein ingredient make a GMO-free claim? Has it been co-processed with other ingredients that need to be labeled? Does it allow the manufacturer to develop a narrative around sustainability: responsible water, land and fertilizer usage? These topics are becoming increasingly important to consumers today.

There are two major types of protein: globular and fibrous. Globular proteins, the predominant group, are compact, folded and generally water-soluble.  Fibrous proteins, like those in collagen and gelatin, are generally less water-soluble.  Amino acids are the building blocks of protein and differ by side chain.

“Understanding the amino acid composition of a protein provides insights  into potential functionality in the final product. For example, if there are  sulfur-containing amino acids, then expect disulfide bridges in the final  product,” said Mann.

Egg products contain cysteine and serine, which aid in structural stability through bridging. Proteins have a primary, secondary, tertiary and quaternary structure. Understanding the bonding that occurs within these structures also  helps to predict the function and performance in the final product, Mann said.

Denaturation takes the protein from its compact native state to an unraveled state. It may be reversible or irreversible, and partial or complete. Denaturation results in decreased solubility, increased viscosity, altered functionality and some loss of enzyme activity. Denaturing agents include temperature, pH change, shear, high-pressure processing, salt addition, organic solvents, and oxidizing and reducing agents.

Finished product processing may involve additional pH and temperature changes, as well as interactions with air, acids, fat, flavoring agents and other components in the system. Protein ingredients can contribute to water binding, viscosity building, gelation, foaming, emulsification and browning. Understanding their functionalities up front can shorten development time; ensure stable products throughout the shelflife; and inspire development of unique functions or novel products.

Food formulators should embrace both old and new protein sources. Dairy and soy are traditional powerhouses. There is growing interest in gelatin for joint health and beauty-from-within. Pulses are already eaten in many regions of the world.

Emerging proteins include algae, canola, oats, flax, hemp, quinoa, rice, sunflower and lemna. Some have wider commercial availability than others. Exploratory proteins include insects, such as crickets and mealworms. RuBisCo is the most abundant protein on earth and is found in every green, leafy material. Developments in newer proteins are increasing at a rapid pace, due to the need to feed more and more people over the next 20+ years.

Industry doesn’t yet know whether consumers will embrace these new ingredients, or if there will be confusion and unforeseen negative baggage. Food formulators should strive to better understand the the concept of linking protein structure to function & applications, while exploring both the functionality of traditional proteins as well as taking opportunities to embrace novel proteins, Mann concluded.

Julie Mann, MSc, Staff Scientist, The Hershey Company,,

The summary above is an excerpt from the “2015 Protein Trends & Technology Magazine: Formulating with Proteins.”