Functionality and structure of yellow pea protein isolate as affected by cultivars and extraction pH

Authors: RAO, JIAJIA - North Dakota State University; CUI, LEQI - North Dakota State University; CHEN, BINGCAN - North Dakota State University; BANDILLO, NONOY - North Dakota State University; Ohm, Jae-Bom; WANG, YECHUN - North Dakota State University

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2020
Publication Date: 5/10/2020
Citation: Rao, J., Cui, L., Chen, B., Bandillo, N., Ohm, J., Wang, Y. 2020. Functionality and structure of yellow pea protein isolate as affected by cultivars and extraction pH. Food Hydrocolloids. https://doi.org/10.1016/j.foodhyd.2020.106008.
DOI: https://doi.org/10.1016/j.foodhyd.2020.106008

Interpretive Summary: Pea (Pisum sativum L.) has been a promising source of plant-based protein. The utilization of pea proteins as functional ingredients in food products depends on their functional attributes such as solubility, emulsifying and foaming properties, etc. The food industry always requires pea protein isolates (PPI) that have better functionalities. In this study, we studied the functional attributes of PPI that were extracted from four different pea cultivars using alkaline solutions with different pH levels (8.5, 9.0, 9.5, 10.0). Results showed that pea cultivars were significantly different for the solubility, emulsifying capacity and stability, and foaming capacity of PPI. The pH levels of extraction solution also affected emulsifying stability, and foaming capacity and stability. Increasing pH of alkaline extraction solution from 8.5 to 10.0 resulted in PPI with reduced surface tension, which contributed to their better foaming capacity and stability. The protein structural characteristics were also evaluated. Pea cultivars varied significantly for protein chemical structure characteristics. The information obtained in this experiment will be a valuable reference to produce PPI which have desirable functional attributes.

Technical Abstract: Pea (Pisum sativum L.) has been a promising source of plant-based protein, but better protein functionalities are needed by the food industry. In this study, pea protein isolate (PPI) was obtained by alkaline extraction-isoelectric precipitation method, followed by spray-drying. The functional attributes of PPI, as affected by four different cultivars (Agassiz, Spider, Trapeze and ND Trial) and four alkaline extraction pH (8.5, 9.0, 9.5, 10.0), were firstly studied. Results showed that cultivars had significant impacts on the solubility, emulsifying capacity and stability, and foaming capacity and stability of PPI, while alkaline extraction pH only affected emulsifying stability, and foaming capacity and stability. The protein structural characteristics were then evaluated using sodium dodecyl sulfate polyacrylamide gel electrophoresis, size exclusion chromatography with multi-angle static light scattering, quantification of sulfhydryl/disulfide group and Fourier transform infrared spectroscopy analyses. The contents of legumin, aggregates, exposed sulfhydryl group and ß-turn structure were different among PPI of different cultivars. Additionally, increasing alkaline extraction pH from 8.5 to 10.0 resulted in PPI with reduced surface tension, which contributed to their better foaming capacity and stability.