Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

Bishnu Karki

Keywords

Dietary Fiber, Fermentation, Protein Extraction, Saponins, Starch, Total Phenolics

Abstract

Yellow peas are a rich source of protein and phytochemicals. Peas are compatible with many diets restricted by sensitivities, allergies, or personal choice. As a result, peas are gaining popularity in food markets, despite the challenges they present. The biggest challenges for pea proteins in food markets are high content of fiber, starch, and saponins. These components cause processing challenges and create undesirable textures and bitter flavors. Pea proteins are typically extracted with alkaline extraction or air classification methods which result in 80% and 50% protein products respectively. With low protein purity, these products are not competitive with other, more established, plant-based proteins like soy. The objectives of this study are to (1) Determine the effect of fungal fermentation on the protein, saponin, phenolic, and dietary fiber content of dry processed proteins (DPP), (2) Describe the effects fungal fermentation has on the saponin, protein, starch, and phenolic composition of dehulled peas (DHP), (3) Understand how fermentation, drying method, and antimicrobial techniques affect alkaline extraction and isoelectric precipitation from DPP and DHP. In DPP and DHP, fermentation has potential to improve composition. Fermentation increased protein, total saponins, and total phenolic content for both substrates. During fermentation, total dietary fiber decreased in DPP, and starch content decreased in DHP. With high fiber- and starch- contamination in DPP and DHP respectively, these results indicate that fermentation may reduce these unwanted components. In addition, increased phenolic- and saponin content may provide increased antioxidant activity and health benefits. Extraction of both DPP and DHP indicate that chemical antimicrobials are superior to autoclaving in terms of protein yield, extraction yield and protein content of isolates. Drying method does not significantly impact protein extraction. Fermentation increased solubility but resulted in unrecoverable protein during isoelectric precipitation. Methods such as ultrafiltration may be a superior method for protein recovery. These results demonstrate that fungal fermentation has potential to broaden the application of pea proteins in food markets. Fungal fermentation improves composition of DPP and DHP in regard to protein and starch as well as non-nutritive components like saponins, phenolics and fiber. Fermentation also may produce a more soluble protein isolate.

Library of Congress Subject Headings

Peas -- Processing.
Peas -- Nutrition.
Plant proteins.
Fungi -- Biotechnology.
Fermentation.

Number of Pages

156

Publisher

South Dakota State University

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Rights Statement

In Copyright