Functional Properties of Plant Proteins

Originally Published: June 1, 2018
Last Updated: February 10, 2021
Functional Properties of Plant Proteins

June 1, 2018 — Trends driving consumer demand for plant proteins include health and well-being; the desire for plant-based and clean label products; and concerns related to food security and sustainability. The number of opportunities to use plant-based proteins will grow, as the number of novel protein types grows, as well. Choosing the right plant protein for a formulation depends on several factors, from source availability and cost; to nutritional considerations; to taste and the functional properties of plant proteins—as well as consumer perception and the presence of anti-nutrients.

Functional Properties of Plant Proteins

Plant proteins provide a wide array of functionalities in various applications. Properties will vary, depending on the method used to process the protein ingredient. Click image to see large PDF version.

“In comparing plant proteins with egg and other animal proteins or in trying to replace them, the first and most important challenge is the taste,” said Anusha Samaranayaka, Ph.D., Senior Scientist, POS Bio-Sciences, in her presentation “Plant Proteins: Opportunities, Challenges & Tips for Successful Use in Formulations.” “No matter how functional or how the protein ingredient looks, it doesn’t fly if it doesn’t taste good,” she added.

Careful consideration about the protein source being used in the creation of an ingredient is crucial. Functionality and taste are very important; however, when processing an ingredient, co-products also merit a consideration. Cereals and pulses are composed of about 50-60% starches and fibers. If the goal is to make a protein ingredient using a raw material containing 25% or less protein, finding an application for these co-products is a must; it’s not economically feasible otherwise, Samaranayaka noted.

Variables at different stages of plant protein ingredient production affect flavor, functionality and quality of the ingredient. These stages include growing, harvesting and storage; extraction, fractionation and drying; further processing, such as fermentation, germination and physical, chemical or enzymatic modification; and formulation parameters, such as temperature, pH and mixing. For instance, “protein content deviates with the climate and soil, and even the maturity of harvesting; this affects downstream processing,” explained Samaranayaka. If it’s difficult to remove the seed coat during dehulling—for example, if the seed is not mature—off-flavor notes can occur in the final product. The extraction and fractionation techniques, and most importantly the protein drying technique, are very important in creating these functional protein ingredients, as is further processing, she added.

Functional Properties of Plant Proteins

The molecular structure of plant vs. animal proteins differs. Cereals and pulses mainly have globular, storage proteins, while meat, egg and milk proteins have more soluble and fibrillar-like proteins. Understanding different plant proteins at the molecular level helps in creating processes to effectively extract and isolate the functional proteins of interest. It is also helpful in use of enzymatic, chemical or physical methods to further modify protein ingredients’ functionality.

“Establishment of standard methods for assessing the protein functionality and creating a functionality database of different protein ingredients available would really help food formulators in selecting protein ingredients for their specific needs,” suggested Samaranayaka.

Researchers and food companies have had some success with product modifications to see if plant proteins can replace animal proteins in products. “These process modifications additionally help remove some of the anti- nutrients and off-flavors. Processing also improves the digestibility of these proteins,” Samaranayaka stated.

One example is the creation of meat analogs or alternate meat products. Since most plant proteins have a globular structure, rather than the fibrous structure of meat muscle, they won’t provide that “bite” that is typical of a burger. What can you do? The globular structures must be unfolded, and the proteins aligned, so as to make aggregates that come close to the structure of fibril proteins. That’s what techniques like extrusion can do, continued Samaranayaka.
Plant proteins can also be used in non-dairy beverages, but protein modification via controlled enzymatic or chemical hydrolysis is often needed to improve the protein’s solubility. Improving the solubility helps make the beverage’s texture, consistency and mouthfeel more appealing to consumers.

The composition of each plant protein type differs, as does its inherent flavor and protein functionality. If changing the raw material source or the process used in protein ingredient preparation does not produce the needed flavor and texture in the final product, the food formulation stage can also be used to improve both flavor and textural issues. Approaches include incorporation of a physical or chemical process; or of additives, such as flavor masking agents, companion flavors and/or stabilizers.

Most importantly, finished formations should be presented to consumers in a way that is appealing in flavor and texture. “It’s a complicated story. Growers, food chemists, ingredient manufacturers and formulation scientists have to work together to come up with these crave-worthy creations using different plant protein sources,” Samaranayaka concluded.

Click on this link to access the PowerPoint of the presentation: “Plant Proteins: Opportunities, Challenges & Tips for Successful Use in Formulations,” Anusha Samaranayaka, Ph.D., Senior Scientist, POS Bio-Sciences

This presentation was given at the 2018 Protein Trends & Technologies Seminar.

Click to see past and future Protein Trends & Technologies Seminars.