Whey Protein Isolate Microgel Properties Tuned by Crosslinking with Organic Acids to Achieve Stabilization of Pickering Emulsions

Abstract

Whey protein isolate (WPI) can be used effectively to produce food-grade particles for stabilizing Pickering emulsions. In the present study, crosslinking of WPI microgels using organic acids (tannic and citric acids) is proposed to improve their functionality in emulsions containing roasted coffee oil. It was demonstrated that crosslinking of WPI by organic acids reduces the microgels’ size from ≈1850 nm to 185 nm and increases their contact angle compared to conventional WPI microgels, achieving values as high as 60°. This led to the higher physical stability of Pickering emulsions: the higher contact angle and smaller particle size of acid-crosslinked microgels contribute to the formation of a thinner layer of particles on the oil/water (O/W) interface that is located mostly in the water phase, thus forming an effective barrier against droplet coalescence. Particularly, emulsions stabilized by tannic acid-crosslinked WPI microgels presented neither creaming nor sedimentation up to 7 days of storage. The present work demonstrates that the functionality of these crosslinked WPI microgels can be tweaked considerably, which is an asset compared to other food-grade particles that mostly need to be used as such to comply with the clean-label policy. In addition, the applications of these particles for an emulsion are much more diverse as of the starting material.

Aqueous microgels with engineered hydrophobic nano-domains

“…tannic acid. 99 Resulting modified WPMs provided a more effective adsorption at O/W interfaces than conventional WPMs, although still possessing a rather hydrophilic polymer structure. In addition, their particle size and distribution were smaller than those of conventional WPM microgels.…”

Recent progress in Pickering emulsions stabilised by bioderived particles

“…Crosslinking WPM particles with organic acids, such as citric and tannic acid, has been shown to produce smaller, less polydisperse particles that also appeared to offer a better emulsion stability compared to conventional WPM stabilised emulsions. 105 …”

Effect of Corn Starch Granules on Stabilizing the Foam Structure of Ultrasonically Modified Whey Isolate Protein

“…The rigid structure in its spatial conformation is considered to be the basis for its application in food processing [ 2 ]. In general, food proteins can act as good foaming agents to give foam-based foods a satisfying appearance, taste, and texture, such as ice cream, angel cake, and salad dressings [ 3 ]. However, under the diverse environmental conditions of food processing, thermally unstable protein foam systems are not very stable [ 4 ].…”

“…Therefore, a simple and efficient foam stabilization technique may be beneficial to solve this problem. Recently, several teams have found that microparticles formed from biomacromolecules might possess excellent interfacial stabilization [ 3 , 11 ]. Protein microgels and starch granules have been shown to be embedded at the air-water interface under specific conditions to achieve stability of the foam system [ 3 , 11 ].…”

“…Recently, several teams have found that microparticles formed from biomacromolecules might possess excellent interfacial stabilization [ 3 , 11 ]. Protein microgels and starch granules have been shown to be embedded at the air-water interface under specific conditions to achieve stability of the foam system [ 3 , 11 ]. These microparticles are stabilized at the interface similar to armor, which on the one hand prevents gas exchange on both sides of the interface and on the other hand inhibits the proximity and agglomeration of adjacent bubbles [ 12 ].…”