Enhanced stabilization of cloudy emulsions with gum Arabic and whey protein isolate

Cloudy emulsions are oil-in-water (O/W) emulsions normally prepared as concentrates, further diluted, per request, into the final beverage. The cloudy emulsion provides flavor, color, and cloud (turbidity) to the soft drink. These systems are stabilized by emulsifiers and/or amphiphilic polysaccharides. Cloudy emulsions based on naturally occurring food grade emulsifiers were studied in the present work. Two charged natural biopolymers, whey protein isolate (WPI) and gum Arabic (GA), are interacted in aqueous solution to form charge-charge interactions improving the emulsion stability. The emulsions were high sheared (Microfluidizer) and characterized by particle size distribution analysis (DLS), optical centrifugation (LUMiFuge), optical microscopy observations, and turbidity measurements. Emulsions obtained from 10 wt% of 3:1 wt. ratio WPI:GA, at pH 7 (10 wt% canola oil) show better stability than emulsions stabilized by GA or WPI alone. The droplet sizes were smaller than 1 μm and did not grow significantly during 1 month of incubation at 25 °C. The D-limonene-based emulsion droplets were larger (>2 μm) than those made with vegetable oils immediately after preparation and underwent significant droplet size increase (coalescence) within 1 month (>8 μm). The emulsion with turbidity suitable as a cloudy emulsion was composed of 3 wt% WPI:GA (3:1) and 20 wt% canola oil.