Boosting the stability of protein emulsions by the synergistic use of proteins and clays

Abstract

The preparation and the properties of high-pressure emulsions based on five different proteins are reported. As proteins, we used the well-studied bovine serum albumin (BSA), a biotechnical produced hydrophobin called H Star Protein B® (HPB), a protein isolate from soybeans, a wheat protein isolate (Plantasol W), and a commercially available yeast extract. All emulsions were characterized by visual appearance, light microscopy, conductivity, and rheological measurements. Beside the emulsion based on soy protein isolate, all other samples showed phase separation under the used conditions (0.5 wt.% protein; 50 wt.% oil). Plantasol W and yeast extract formed the most unstable emulsions showing typical instability processes like coalescence. Gel-like properties have been observed for emulsions based on BSA, soy protein isolate, and HPB. The same proteins were also used to stabilize emulsions after their adsorption on clay particles. Interestingly, all emulsions had gel-like properties with a yield stress value and were stable to the used conditions. It is concluded that the gel character results from the stickiness of the protein covered oil droplets and is independent from the used protein type. The proteins which are adsorbed on the oil droplets can still interact and bind to proteins on other oil droplets.

Production and characterization of stable foams with fine bubbles from solutions of hydrophobin HFBII and its mixtures with other proteins

“…The hydrophobins cover the bubbles with a highly elastic adsorption layer, which suppresses both foam disproportionation and bubble coalescence, without increasing the viscosity of the aqueous phase [8][9][10]14]. The hydrophobins are also used to stabilize oil-in-water emulsions [15,16] and aerated emulsions [17,18]. The adhesive properties of hydrophobins have been utilized for immobilizing functional molecules at surfaces [19], and for surface modification by appropriate coatings [20].…”

Limited coalescence and Ostwald ripening in emulsions stabilized by hydrophobin HFBII and milk proteins

“…Reger et al [36] investigated emulsions stabilized by two types biotechnically produced watersoluble recombinant hydrophobins and studied the rheology of these emulsions. Further, these authors demonstrated that the combined action of hydrophobins and clay particles produce synergistic effect on emulsification and emulsion stability [37][38][39][40]. Cox et al [41,42] established that hydrophobin HFBII can be used as stabilizer of aerated emulsions for the food industry.…”

Structural studies of adsorbed protein (betalactoglobulin) on natural clay (montmorillonite)

“…1,2 Alternatively and along with the advent of nanotechnologies, many studies have focused on macromolecule layered silicate interactions for the design of advanced hybrid materials with applications in elds as diverse as catalysis or wine ning and food processing. [3][4][5][6] A particular interest of protein-clay systemsor more general protein-porous materialsconcerns their ability to simulate conned environments for structural biology approaches. [7][8][9] While macroscopic descriptions of the phenomena provide interesting information it is felt that a molecular-level investigation of the interaction between clay layers and proteins will be essential for a rational improvement of desired properties.…”