Stability of Beverage Flavor Emulsions

Contact Author Chee-Teck Tan and Joanna Wu Holmes
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Many of our food items are in emulsion form. An obvious example is milk. It is a natural emulsion of butter fat dispersed in a protein solution. Many of our processed foods are also in the form of an emulsion, for example, mayonnaise, salad dressings, ice cream, whipped cream, coffee whitener, cake batter, frankfurter, and others.

Beverage flavor emulsion is a special type of emulsion. It is prepared in the form of a concentrate and then diluted in sugar solution to make into soft drinks. The soft drinks can be non-carbonated still or carbonated drinks. In soft drinks the flavor emulsion provides flavor, cloudiness and color for the beverage. These properties make the beverage flavor emulsions different from other food emulsions. Although for coffee dairy cream or coffee whiteners are used in the diluted form in the beverage, they are consumed almost immediately, and the stability in the diluted form is of no concern. On the contrary, beverage flavor emulsions are required to have good stability in both concentrate and diluted form of a finished beverage.

Beverage flavor emulsions are oil-in-water (O/W) emulsion. A typical composition of orange flavor emulsion includes orange oils and weighting agents (e.g., ester gum, BVO, SAIB and dammar gum). The water phase usually contains water, hydrocolloid (e.g., gum arabic), citric acid, preservatives and colorings (e.g., FDC colors and β-carotene). Due to the shortage of gum arabic in the last two years, the other kinds of gums and modified starches are being used as substitutes. Hydrocolloids serve as a stabilizer for the emulsion. Some hydrocolloids, such as gum arabic, also provide emulsifying properties in the emulsion. Citic acid is used for pH control, and benzoate as preservative. Both are for the purpose of preventing microbiological spoilage. Colorings are for aesthetic purposes. In the oil phase, flavor oil is usually composed of essential oils or citrus oils. Weighting agents can also be called density adjusting agents, i.e., materials which are oil soluble with no flavor of their own and have density higher than the flavor oil. As the name implies, they are added to flavor oil to increase the oil phase density and, with the flavor oil, become cloudifiers.