Stability behavior of emulsions formulated with whey proteins

CRISTIÁN HUCK IRIART; JAIME A. RINCÓN CARDONA; MARIA LIDIA HERRERA

Congreso; IV Congreso Internacional de Ciencia y Tecnología de los Alimentos; 2012

Milk whey is a by-product from the cheese industry, generated in great amounts. During cheese manufacturing soluble whey proteins (primarily lactalbumins and lactoglobulins), lactose and minerals are drawn off in the whey. This by-product is generally processed by ultrafiltration and spray drying giving an interesting ingredient for the food industry. Dry whey has good functional properties such as emulsifying, water/fat holding, foaming, thickening or gelling capacity. Two whey powders with different protein contents of 35 and 75 wt% were used in this study. Aqueous phase was formulated with 20 wt% of sucrose or with 0.3 wt% xanthan gum. Stability of the systems were studied by Turbiscan, particle size distribution by dynamic light scattering (DSC) and microstructure by confocal laser scanning microscopy (CLSM).The whey powders selected for this study had two different protein contents of 35 or 75 wt%. Emulsions were prepared using an Ultraturrax T 18 (pre- emulsions) and were further homogenized by ultrasound (fine emulsions). Particle size significantly diminished when emulsions were further homogenized by ultrasound. In both cases, pre- emulsions and fine emulsions, addition of 20 wt.% sucrose or 0.3 wt.% xanthan gum also diminished average mean diameter of distributions. Turbiscan studies show that when emulsions were stabilized by 2 or 5 wt.% whey protein, they destabilized mainly by creaming as may be noticed from the delta back scattering profiles. Concentrations greater than 7 wt.% corresponded to stable emulsions. Addition of 20 wt.% of sucrose or 0.3 wt.% xanthan gum to the aqueous phase significantly increased stability. Creaming was slower for the 2 wt.% emulsion. Emulsions with 5 wt.% protein or higher concentrations were stable. CLSM images showed that xanthan gum emulsions had the most unhomogeneous structure but despite that emulsions with xanthan gum were the most stable of all. When emulsions had no additives in the aqueous phase, stability was improved with protein concentration. For the same protein concentration, sugar enhance stability as may be noticed from the Turbiscan profile. Addition of xanthan gum improved stability at low protein concentrations but the interactions between whey protein and xanthan gum destabilized the systems at high protein concentrations.