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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Functional Foods Research » Research » Publications at this Location » Publication #430842
Research Project: Advancing Sustainable Technologies to Improve End-Use Quality of Underutilized and Climate-Resilient Food Crops for Value-Added Food and Consumer Products

Location: Functional Foods Research

Title: Potential of alfalfa seed as a source of protein concentrates for human food

Author
item PAUL, SAYANTINI - University Of Nebraska-Lincoln
item SINGH, MUKTI
item LIU, SEAN
item ROSE, DEVON - University Of Nebraska-Lincoln
item MAJUMDER, KAUSTAV - University Of Nebraska-Lincoln

Submitted to: Food & Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Alfalfa seeds are rich in proteins and other nutrients, and their seeds are sprouted and used as garnish for salads and other foods. In this study we explored alfalfa seeds as a plant-based source of food proteins using aqueous solutions with different acidity/alkalinity to extract the proteins from the seeds. Given that the extracted proteins will be used as food ingredients, we investigated the important nutritional and functional properties that are critical for food applications, in addition to yield: solubility of extracted proteins, amino acid profiles, protein digestibility, emulsifying activity index, emulsion stability, and foam stability. We found that aqueous extraction of alfalfa seed proteins at pH 10 provided the best yield, solubility of proteins, emulsion/foaming related properties, and nutritional values. This discovery will lead to the development of commercial alfalfa food proteins production thus providing alfalfa farmers with high-value market for their crop.

Technical Abstract: Alfalfa (Medicago sativa L.), primarily grown as high-quality forage, contains more than 30% protein in seeds and represents a promising yet underutilized resource for food applications. This study investigated protein extraction from alfalfa seeds using combinations of saline (0-5% NaCl; S0-S5) and pH conditions (2, 10, and 12; P2, P10, P12, respectively). Based on yield and purity, the amounts of water at pH 2 (S0P2), pH 10 (S0P10), and pH 12 (S0P12) was were selected. Protein purity did not differ significantly (p > 0.05); however, S0P10 exhibited higher soluble protein content (61.05%), lower surface hydrophobicity (70.9 a.u.), and greater total essential amino acid content (39.23 g/100 g) than S0P2 and S0P12 (p < 0.05). Solubility of S0P2 (40-70%) remained lower at pH 2, 7, and 9 than S0P10 (86-90%) and S0P12 (67-94%) (p < 0.05). Emulsifying activity index ranged from 56-71 m²/g, with S0P12 highest (p < 0.05). Emulsion stability was higher in S0P10 (17.5%). Foaming stability and capacity ranged from 95-97% and 15-22% respectively. Digestible Indispensable Amino Acid Score (DIAAS) values for S0P10 were higher (p < 0.05) across all groups (0.78 ± 0.02 for infants, 1.40 ± 0.04 for children, and 1.60 ± 0.05 for adults). Trypsin inhibitor activity and saponin content peaked in S0P10 (4.25 TUI/mg and 13.5 mg/g), while phytic acid was highest in S0P2 (1.68 g/100 g) (p < 0.05). Water extraction at pH 10 resulted in higher yields, improved solubility, amino acids, functionality, and DIAAS, establishing alfalfa seed as a high-quality protein source for human consumption.