The Issue
As the demand for plant proteins continues to grow, there is a need to develop alternative sources of protein other than soy protein, which is limited by being sourced from a GMO crop and a “Big Eight” allergen. Yellow field peas have similar agricultural benefits and protein profiles as soybean but are non-GMO and of low allergenicity. While soy protein has undergone decades of research to optimize extraction and processing conditions and evaluate structural and functional properties, pea protein is less researched.
Key Activities
Currently, pea protein is mass produced in a way that can alter its native structure, thus reducing its functionality in food applications. In order to make pea protein competitive with soy protein, there is a need to optimize both the conditions used for pea protein extractions and for functionalization, to produce pea protein isolates (PPI) with high protein purity, preserved structural, and enhanced functional properties. Additionally, the scalability of optimized extraction methods must be evaluated to determine industrial feasibility.
Researchers at the UMN Plant Protein Innovation Center tested two protein extraction protocols (alkaline solubilization with isoelectric precipitation and a salt solubilization coupled with membrane filtration) to optimize pea protein extraction conditions to maximize protein purity and yield. They then characterized the impact of the two “bench-top” extraction methods on the pea protein structure and functionality. They then conducted a pilot scale study to evaluate the impact of a larger-scale production on the protein’s structure, functionality, nutritional quality and flavor. In addition, the team used cold plasma treatment to improve the pea protein functionality, which resulted in enhanced emulsification and gelation properties.
Results
Overall, this study demonstrated successful optimization and scalability of two pea protein extraction methods: alkaline solubilization with isoelectric precipitation and salt solubilization coupled with membrane filtration. Both optimized bench-top methods achieved high protein purity and yield, while using relatively non-denaturing conditions. Scaled-up extractions achieved similar protein purity to the bench-top counterparts. Compared to commercially available PPI, the scaled-up PPIs had superior solubility at pH 3.4 (suitable for acidic beverage application) and superior gelation and emulsification properties. While there were slight differences in structural and functional properties between bench-top and scaled-up PPIs, compared to commercially available PPIs, scaled up PPIs were less denatured, resulting in superior functionality that should be advantageous to industry. Cold plasma treatment further enhanced emulsification and gelation properties of the produced pea protein isolates, surpassing commercial soy protein isolates.
This study is significant in demonstrating that PPI, with superior functionality to commercially available PPI, as well as commercially available soy protein isolate, can be produced on a large scale through both the traditional pH extraction and the novel salt extraction coupled with membrane filtration. Functionalization of the protein via cold plasma and Maillard-induced glycations has been successful. A patent related to these process discoveries — Method for Producing Functional Pea Protein 63/107,797 — has been applied for.
Public Value
The global protein ingredient market was valued at $38 billion in 2019 and is expected to grow at a rate of 9.1 percent from 2020 to 2027. Protein ingredients have gained prominence in the food industry because of escalating consumer awareness and demand for healthy foods. In general, consumers want more protein in their diet, sustainably sourced. Accordingly, food industries are interested in commercializing products formulated with ingredients derived from environmentally sustainable crops. From a sustainable agriculture perspective, adding peas to crop rotations enhances the structure, nutrient content and levels of organic matter in the soil, increasing the yields of subsequent crops. From a manufacturer’s, and subsequently consumer’s perspective, pea proteins are not as yet allergenic, nor genetically modified. In order to meet both consumer demand and desired eating experience, the expansion of options and functionality of protein ingredients is essential for product development and manufacturing.