Reflections about the functional potential of legume proteins A Review

Abstract

The term "functional potential" was introduced to better approach to the understanding of the relationships between the structure and the functional properties of food proteins. Although in practice the complex of structural features of a protein contributes to its functionality, it is very useful to regard the functional potential of the protein surface on the one side and to look on special effects of protein conformation (role of compact or unfolded state) on the functionality on the other side. This point of view may help to design the best strategy of modification of the protein structure and functionality. The special situation of the oligomeric legume storage protein, i.e. legumin-like 11 S globulins and vicilin-like 7 S globulin, and the structural and functional modification of 11 S globulin by limited tryptic hydrolysis and by acylation are discussed in this paper.

The physicochemical properties of legume protein isolates and their ability to stabilize oil-in-water emulsions with and without genipin

“…A protein with high surface hydrophobicity can readily align at the oil-water interface, and re-orient itself such that its hydrophobic moieties position themselves towards the oil phase and the hydrophilic moieties towards the aqueous phase (Schwenke 2001;Damodaran 2005). Depending on its amino acid sequence and the level of folding/unfolding of a protein at the interface, various loops or tails can develop in which sections of the protein extend from the surface of the droplet into the continuous phase creating a steric hindrance which reduces the likelihood of aggregation, flocculation and coalescence between neighboring droplets.…”

“…Depending on its amino acid sequence and the level of folding/unfolding of a protein at the interface, various loops or tails can develop in which sections of the protein extend from the surface of the droplet into the continuous phase creating a steric hindrance which reduces the likelihood of aggregation, flocculation and coalescence between neighboring droplets. (Schwenke 2001;McClements 2004;Damodaran 2005). The surface characteristics of a protein, within an emulsion, are reliant on the extent of protein interaction with both its dispersive solvent/phase, and with the interface.…”

“…The surface characteristics of a protein, within an emulsion, are reliant on the extent of protein interaction with both its dispersive solvent/phase, and with the interface. Accessible surface area, unfolding and re-orientation at the interface may explain how protein isolates with different physicochemical properties may exhibit similar emulsification properties and vice versa (Schwenke 2001).…”

“…In general, proteins that have higher surface hydrophobicity tend to be negatively correlated to solubility (Can Karaca et al 2011), however in the present study, CPI showed both the highest solubility and surface hydrophobicity which reflects the complexity behind fully understanding the structure-function mechanism related to solubility. This could be a factor not of the average surface characteristics (e.g., charge vs. hydrophobicity), but rather of the apparent surface characteristics, which are influenced by the frequency and distribution of charges on the folded protein surface (Schwenke 2001;Tang and Sun 2011).…”

“…Emulsifiers are comprised of both hydrophobic and hydrophilic moieties that become integrated into the oil-water interface to lower the interfacial tension (Bos and van Vliet 2001). The effectiveness of protein-based emulsifiers is dependent on properties of the protein (e.g., source, size, solubility, concentration, conformation and surface characteristics) (Schwenke 2001;McClements 2007); emulsification conditions (e.g., level and duration of shear, oil/water ratio, and type of homogenizer) and solvent effects (e.g., temperature, pH and the presence of salts) (McClements 2004;Can Karaca et al 2011). Proteins are ideal materials for improving emulsion stability due to their amphiphilic nature (i.e., having both hydrophilic and hydrophobic moieties), enabling them to align at, or unfold at the oil-water interface to lower interfacial tension and form a cohesive viscoelastic coating/film around the droplets (Tcholakova et al 2006).…”