Pea Protein’s Natural Emulsifying Abilities

Food and beverage designers frequently face a challenge in making more-sophisticated products that meet consumer needs while using label-friendly ingredients. Pea protein might provide an answer for certain applications based on new research from University of Manitoba in Canada.

According to the study, the food industry has seen “increased interest in plant-derived food ingredients such as those from pea seeds because of consumers’ demand for cholesterol-free and low-fat food products." While soybean ingredients dominate the sector, yellow field-pea ingredients can provide similar nutritive and functional properties to food and beverage formulations.

“The study was designed to look at potential contributions to food functionality of protein fractions present in the pea protein isolate," says one of the study’s authors, Rotimi Aluko, PhD., Professor and Chair of the Graduate Program, Department of Human Nutritional Sciences, University of Manitoba, Winnipeg. “Commercial applications include replacing meat proteins to formulate low-fat meat products, production of protein-fortified beverages and manufacture of protein gels."

Researchers analyzed commercial yellow pea seed flours prepared by a patented wet-milling process and pea protein isolate (PPI) for emulsifying and foaming properties at pH 3, 5, and 7 and compared the results to soybean protein isolate (SPI). The ingredients tested included two high-fiber products, Centara III and Centara IV, two starch-fiber products, Centu-Tex and Uptake 80, one pea protein isolate (Propulse) and one high-starch product, Accu-Gel, from Nutri-Pea Ltd. (Portage la Prairie, Manitoba, Canada) and soybean protein isolate PRO-FAM 974 from ADM (Decatur, IL).

The researchers found that pea protein isolate and SPI formed emulsions with significantly smaller oil droplet sizes than flours that primarily contained fiber or those that consisted mainly of starch. Data showed that PPI was better at emulsifying than SPI at pH 7, and was a better foaming agent at pH 3 and pH 7, although foaming capacity varied with sample concentration. A smaller particle-size range in the pea protein produced significantly smaller emulsion-oil droplets. Adding pea starch to SPI emulsions produced a synergistic effect and increased emulsification capacity (reduced emulsion oil-droplet size) compared to SPI or starch alone.

Gel electrophoresis revealed that commercial pea protein isolate and its fractionated proteins had minimal level of disulfide bonds. According to Aluko, this “limits intense protein-protein interactions and could allow the manufacture of soft food gels using high concentrations of the proteins. But the protein is not suitable for the manufacture of hard food gels." In addition, he continues, “the disulfide bond is a source of sulfur in human nutrition and is desirable for synthesizing cellular glutathione (an antioxidant) and it can also provide the liver with the sulfur required to detoxify undesirable compounds, which enhances their excretion in the urine."

The researchers concluded that pea protein isolate had generally significantly higher emulsion and foam-forming properties than SPI, and that pea starch can improve the quality of SPI-stabilized food emulsions.

Sources:

* Food Chemistry: Functional properties of protein fractions obtained from commercial yellow field pea (Pisum sativum L.) seed protein isolate