Molecular Properties of Flammulina velutipes Polysaccharide-Whey Protein Isolate (WPI) Complexes via Noncovalent Interactions.

Jiaqi Shang,Xiangyu Teng,Minhe Liao,Hao Li,Yan Xu,Ritian Jin,Ligang Zhang,Ning Liu

doi:10.3390/foods10010001

Abstract

Whey protein isolate (WPI) has a variety of nutritional benefits. The stability of WPI beverages has attracted a large amount of attention. In this study, Flammulina velutipes polysaccharides (FVPs) interacted with WPI to improve the stability via noncovalent interactions. Multiple light scattering studies showed that FVPs can improve the stability of WPI solutions, with results of radical scavenging activity assays demonstrating that the solutions of the complex had antioxidant activity. The addition of FVPs significantly altered the secondary structures of WPI, including its α-helix and random coil. The results of bio-layer interferometry (BLI) analysis indicated that FVPs interacted with the WPI, and the equilibrium dissociation constant (KD) was calculated as 1.736 × 10−4 M in this study. The in vitro digestibility studies showed that the FVPs protected WPI from pepsin digestion, increasing the satiety. Therefore, FVPs effectively interact with WPI through noncovalent interactions and improve the stability of WPI, with this method expected to be used in protein-enriched and functional beverages.

Highlights

Whey protein is a natural byproduct of cheese production and has high nutritional value
The formation of Flammulina velutipes polysaccharides (FVPs)–Whey protein isolate (WPI) complex changed the properties of WPI particles, which can be assessed by the measurement of the particle size and zeta potential
The apparent sizes of the FVP–WPI complexes and WPI at pH 4.5 are presented in Figure 1A, which showed that the particle sizes for the FVP–WPI complexes were smaller than those measured in solutions with WPI alone

Summary

Introduction

Whey protein is a natural byproduct of cheese production and has high nutritional value. Covalent interactions always occur through Maillard reactions, while noncovalent interactions result mainly from hydrophobic interactions, hydrogen binding, or electrostatic attraction under various conditions [10,11,12]. Time-consuming nature, and other parameters in the generation of food products may have harmful effects to health, such as mutagenicity and metabolic diseases [14]. When the pH of the reaction system is lower than the pI of protein, a strong electrostatic attraction occurs between the inversely charged protein and polysaccharide, forms a strong electrostatic complex (the pI is the pH value at which the surface of a molecule is uncharged) [15]. The electrostatic attraction can make the protein and polysaccharide complexes keep the nutritional values without promoting detrimental health effects

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Results