Mechanisms of molecular and structural interactions between lentil and quinoa proteins in aqueous solutions induced by pH recycling

Abstract

There has been a growing interest in plant proteins due to their beneficial health effects, low cost and variety of applications in food industries. The low solubility of lentil proteins (LPs) is one of the significant factors that limit their use in food applications. Quinoa proteins (QPs), which have high water solubility, were combined with LPs at pH 12 to generate LP-QP complexes to generate pH-based soluble protein compounds. The LP-QP complexes demonstrated a large surface charge with an increase solubilisation of the protein complexes by more than 85%, together with resistance to protein aggregation. The combination of LPs to QPs led to a significant increase (P < 0.05) in unique tertiary and secondary protein structures as determined by the protein-protein interaction (PPI) technique involving pH recycling. Interactions between LPs and QPs affected the surface morphology of the protein complexes formed. Electrostatic interactions, hydrophobic forces and hydrogen bonding were indicated to play key roles in the PPIs. The capacity of pH cycling to illustrate the above protein interactions shows that this is a robust approach for assessing the emulsion and foaming properties of food proteins.

Mechanism of the structural interaction between whey and lentil proteins in the unique creation of a protein structure

“…The poor solubility of LPs is the main factor which restricts its industrial applications. Raw LPs was reported to have a solubility of around 55% at pH 7 (Jarpa‐Parra et al., 2014; Alrosan et al, 2021c). Therefore, enhancing the solubility of LP‐based protein complexes with the aid of WPIs is the desired target to achieve in this study.…”

“…The emission decreased after complexation with an increasing amount of WPIs at pH 7.0 (Figure 1b). The interaction or complexation of a protein with a foreign protein (for this case, WPIs) reduces the fluorescence intensity of the protein complexes and the intensity reduces with the increase in the concentration of foreign proteins (Wang et al., 2019a; Alrosan et al, 2021c). Therefore, the change in emission proved the occurrence of interaction between proteins in the formation of protein complexes, and not just two types of proteins present together in a mixture.…”

“…The microstructure environment of a protein can be observed through its fluorescence spectrum (Bur et al., 2004; Alrosan et al, 2021c). Modifications in the tertiary structures of a protein could be described through fluorescence emission modifications depending on the excitation of tryptophan residues at 280 nm (W. Liu et al., 2010; Alrosan et al, 2021c). The tryptophan found inside nonpolar conditions can be observed at a maximum emission (λ F max ) of <330 nm (Vivian & Callis, 2001).…”

“…Water solubility of LPs was reported to be approximately 55% at pH 7.0 (Jarpa‐Parra et al., 2014; Alrosan et al, 2021c). Solubility is considered one of the most important functional properties in which other functional properties depend on (Alrosan et al, 2021b).…”

Understanding macromolecular interactions: key to developing new cereal‐based foods

“…The second paper assesses the pretreatment of raw materials to achieve desired functional properties of macromolecules for developing high quality cerealbased foods. Alrosan et al (2021) describes in detail the Mechanisms of molecular and structural interactions between lentil and quinoa proteins in aqueous solutions induced by pH recycling. In this study, quinoa proteins (QPs) were combined with lentil proteins (LPs) at pH 12 to generate LP-QP complexes to generate pH-based soluble protein compounds; the complexes demonstrated a large surface charge with an increase solubilisation of the protein complexes by more than 85%, together with resistance to protein aggregation.…”