Germination as a Bioprocessing Strategy for Enhancing Functional Properties and Protein Structural Profiles of Moringa Oleifera Seed Protein Isolates: A Comparative Review with Soy Protein Isolates

Abstract

Moringa oleifera seed protein isolates (MPI) have gained increasing attention as sustainable plant protein alternatives; however, their functional properties remain highly variable and underutilized compared to soy protein isolate (SPI). This review critically evaluates germination as a bioprocessing strategy for enhancing MPI structural and functional properties, including SDS PAGE, solubility, foaming, water holding capacity (WHC), and oil holding capacity (OHC), while providing a comparative perspective with SPI.
Evidence indicates that germination improves MPI functionality primarily through enzymatic proteolysis of storage globulins, resulting in reduced molecular weight, increased surface polarity, and improved protein-water and protein-lipid interactions. Optimal germination (~48 h) enhances solubility by 10-15%, foaming capacity by 15-30%, WHC by up to 50%, and OHC by approximately 20-30%. However, SPI consistently outperforms MPI in foaming and gelation due to its structured glycinin and β-conglycinin fractions.
The review further highlights strong geographic origin effects on MPI functionality, driven by variations in protein composition, particularly the ratio of globulins to cationic albumins. Indian MPI shows acid-soluble albumin dominance, Thai MPI exhibits soy-like solubility behavior, and Cameroonian MPI displays mixed functional profiles. Despite these advances, key gaps remain in molecular characterization, standardization of extraction methods, and integration of omics-based approaches. Germination represents a low-cost, sustainable strategy to enhance MPI functionality, but full industrial competitiveness with SPI will require integrated bioprocessing and a better understanding of genotype-environment-protein interactions.