Effects of Three Different Protein Extraction Methods on Common Buckwheat ( Fagopyrum esculentum Moench) Protein Structure

ABSTRACT Background and Objectives There is limited understanding of buckwheat protein functionality, and the effects of common protein extraction methods on its fundamental structure remain poorly defined. This study aimed to evaluate how different protein extraction methods impacted the fundamental protein structure. In addition to two conventional methods, alkaline extraction–isoelectric precipitation (APE‐IPE) and water extraction (WE), deep eutectic solvents (DESE) were used as a novel protein extraction method. Findings The WE method had the highest protein recovery yield, while DESE exhibited the highest protein purity. The DESE protein exhibited differences in secondary structure and had higher molecular weight fractions in the soluble and insoluble protein fractions compared to the native flour and other protein extractions. The DESE samples imaged under the microscope also exhibited a continuous protein matrix that differed structurally from that of the other samples. The total phenolic content was highest in the WE sample and may have formed a network with proteins. Surface hydrophobicity was highest in the APE‐IPE samples, possibly due to the protein type extracted and its hydrophobic ends. Conclusion The different buckwheat extraction processes affected the tertiary structure to a larger extent than the secondary structure. The range of surface hydrophobicity could indicate large differences in protein functionality. The unique attributes of the DESE method should be further assessed for their functional properties. Significance and Novelty Understanding how processing affects buckwheat protein structure is important for protein application and end‐user functionality. Nonetheless, deep eutectic solvents are an emerging protein extraction process that has not been widely employed for grains. Therefore, this approach is essential for expanding the knowledge of buckwheat protein and its future opportunities.