Composite structure formation in whey protein stabilized O/W emulsions. I. Influence of the dispersed phase on viscoelastic properties

• Published in: Food hydrocolloids Vol. 13; no. 4; pp. 303 - 316
• Main Authors: Reiffers-Magnani, C.K., Cuq, J.L., Watzke, H.J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-07-1999; Elsevier
• Subjects: Biological and medical sciences; Composite; Emulsion; emulsions; Food additives; Food industries; Fundamental and applied biological sciences. Psychology; Gelation; General aspects; heat treatment; Milk and cheese industries. Ice creams; oil water emulsions; particle network; Polymer; polymeric network; Rheology; soybean oil; viscoelasticity; whey protein; Whey proteins; Polymer; Emulsion; Composite; Whey proteins; Rheology; Gelation; Viscoelasticity; Dispersed phase; Heat treatment; Oil water emulsion; Dairy plant by product; Crosslinking; Food additive; Emulsifier; Gelatinization; Aggregation; Fat globule; Adsorption; Hydrocolloid; Whey protein; Rheological properties
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/S0268-005X(99)00013-2

The viscoelastic properties of whey protein stabilized emulsions containing varying amounts of protein and oil were investigated during heat treatment using oscillatory rheology. The emulsions were thoroughly characterized prior to gelation by measuring droplet size and protein adsorption. This emulsion characterization permitted the concentration of protein remaining in the bulk phase of the emulsion to be determined, by taking into account both oil exclusion effect and protein adsorption, and to prepare a cream and a whey protein solution corresponding to the emulsion's dispersed and bulk phases, respectively. Gelation of the phases was investigated separately and was used to better understand how the oil droplets and bulk proteins contribute to gelation of the whole emulsion. The rheology of polymeric solutions, giving the gel point as the
G′–
G″ cross-over, could be applied to the whey protein solution during heat treatment. Regarding the cream, its gelation revealed that the proteins adsorbed at the O/W interface gelled and were responsible for droplet–droplet interactions, leading to a particle gelled network. The rheological behavior of the whole emulsion during heat treatment was in-between those of a polymeric gel and a particle gel. The main parameters influencing the rheology were the bulk protein concentration and the aggregation state of the oil droplets. The bulk protein concentration determined the formation of a polymeric network in the aqueous phase of the emulsion, and the aggregation state of the droplets influenced their possible interactions and the formation of a particle network.