Role of plant protein blends in functional foods and nutraceutical development

Proteins derived from plant sources have, over the past two decades, shifted from being considered nutritional second-best to occupying a genuinely central position in functional food design. Much of this shift is justified. But much of the enthusiasm in commercial and popular discourse has also run ahead of the evidence and this review was written partly to close that gap.
The specific focus here is plant protein blends: combinations of two or more plant-derived proteins, assembled with deliberate intent to correct the nutritional deficiencies and functional limitations that characterize individual sources. Legumes lack sulfur amino acids. Cereals are short on lysine. Oilseeds, nutritionally interesting in other respects, rarely shine when assessed by protein quality metrics in isolation. Blending addresses all of this not perfectly, not without complications, but meaningfully and measurably.
This review covers the rationale and evidence for amino acid complementarity across legume, cereal, pseudocereal, and oilseed protein sources; protein quality scoring by PDCAAS and DIAAS methods; techno-functional behavior in food matrices including solubility, emulsification, gelation and foaming; bioactive peptide generation from blended hydrolysates; the effects of processing technologies including fermentation, germination, extrusion, and enzymatic crosslinking; and the obstacles flavor, anti-nutritional factors, allergenicity, regulatory incoherence that still stand between laboratory findings and widespread commercial adoption. The conclusion is one of qualified optimism: the science is solid enough to justify serious investment, but the remaining challenges are real and should not be glossed over.