Stability of hydrocolloid enriched oil-in-water emulsions in beverages subjected to thermal and nonthermal processing

Abstract

Storage stability of concentrated oil-in-water beverage emulsions subjected to thermal and non-thermal processing was evaluated over 14 days at 22 °C. Emulsions were made with canola oil and aqueous dispersions of Type “A” and Type “B” gelatin and xanthan. They were also conjugated with propylene glycol alginate (PGA), modified starch and modified gum Arabic was studied at pH 3.4 and 7.0. Increase in apparent viscosity was observed with storage for gelatin Type “A” emulsions (pH 7.0) and gelatin Type “B” emulsions (pH 3.4). All emulsions showed shear-thinning behavior associated with droplet flocculation. Increase in the slope of particle size distribution was more obvious for protein (gelatin) stabilized emulsions. Concentrated gelatin Type “A”-modified starch had smaller particle size and greater stability at pH 3.4, followed by gelatin Type “B”-modified starch and gelatin Type “B”-xanthan-PGA both at pH 7.0. Simulated orange beverage (pH 3.0) and dairy beverage (pH 6.8) using stabilized emulsions were pasteurized by heat and high pressure. Emulsions formulated by modified starch produced better stability in both beverage types. Gelatin Type “A” and modified starch conjugate resulted in greater stability compared to other conjugated emulsions. However, gelatin alone failed to stabilize the emulsion systems. The ringing was characteristically associated with emulsions formed with gelatin alone. Neither thermal processing nor high-pressure treatment resulted in destabilization of emulsions.