Composition and structure of interface impacts texture of O/W emulsions

• Published in: Food hydrocolloids 2014-01, Vol.34 (1), p.3-9
• Main Authors: Surel, C., Foucquier, J., Perrot, N., Mackie, A., Garnier, C., Riaublanc, A., Anton, M.
• Format: Article
• Language: English
• Subjects: Aggregation; Emulsion; Emulsions; Food engineering; Heat temperature; Interface; Life Sciences; Milk proteins; Texture
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2013.06.016

Heat treatment applied to milk protein solutions can modify protein denaturation and aggregation state. Whey proteins (WP) are highly sensitive to heat treatment: above 70 °C they form aggregates or gels, while casein micelles (CM) are less affected but can complex with WP. Competitive adsorption during homogenization of milk protein stabilized emulsions leads to the formation of a heterogeneous complex layer at the interface. The aim of this study was to evaluate the effects of heat treatments (60 °C or 80 °C for 5 min) of different CM and WP aqueous mixtures (ratios from 80:20 to 12:88) on the structure of oil-water interface in relation to the texture of the emulsions. Different protein structures induced by heat treatment were characterised by light scattering and microscopy. Emulsion rheological properties were characterized and correlated with the amount of adsorbed protein, the composition and the structure of interface. Three kinds of rheological behavior and four different interfacial structures were characterized. In the first group, the emulsions were liquid, showing no connections between droplets. In the second group the emulsions were structured, the droplets being weakly connected by WP aggregated. In the third group the emulsions gelled, the droplets being connected by CM/WP complex or in other case by aggregated WP. The results are presented in a way that highlights the impact of the composition – structure relationship of the interface layer on the emulsion properties. [Display omitted]