The Science Behind the Flavor: Exploring Emulsions with Dynamic and Electrophoretic Light Scattering
Flavor emulsions are oil-in-water systems stabilized by surfactants or biopolymers. This study uses dynamic light scattering and electrophoretic light scattering to assess droplet size distribution and zeta potential as predictors of colloidal stability
Flavor emulsions are widely used in the food and beverage industry to deliver aroma and taste compounds in a stable and reproducible form. These oil-in-water (O/W) systems rely on colloidal properties, especially droplet size and zeta potential, to ensure physical stability and shelf life.
They are typically composed of volatile or semi-volatile essential oils (e.g., orange or lemon oil), stabilized by emulsifiers such as gum arabic, modified starches, or proteins, along with additives like weighting agents or preservatives. High-shear homogenization or ultrasonic treatment is commonly used to achieve the desired droplet size. (1) To promote stability, flavor emulsions are tailored to specific size ranges.
Nanoemulsions (<100 nm) are optically clear and highly stable, ideal for clear beverages or rapid-absorption applications. Emulsions sized 100–500 nm remain stable but appear turbid, suitable for general beverages. In juices, dressings, and flavored dairy products, droplet sizes typically range from 500 nm to 1 μm. Larger droplets (>1 μm) increase the risk of coalescence and creaming. Generally, keeping droplet sizes below 1 μm enhances stability, improves mouthfeel and flavor release, and contributes to better appearance and long-term shelf life. (2)
Particle size, or more precisely the droplet size of the dispersed phase, plays an important role in determining the physical stability, mouthfeel, appearance, and release behavior of flavor emulsions. Smaller droplets generally result in a more stable emulsion due to reduced gravitational separation and creaming tendencies, while also enhancing flavor retention and offering more controlled release. The characterization of particle size distribution is commonly performed using dynamic light scattering (DLS).
Zeta potential, a measure of the electrical potential at the slipping plane of dispersed particles, is a key indicator of electrostatic repulsion in colloidal systems. High absolute values of zeta potential (positive or negative) suggest strong repulsive forces between droplets, which can prevent coalescence and aggregation over time.
Key Takeaway
Combining droplet size (DLS) and zeta potential (ELS/cmPALS) on Litesizer DLS provides a complete, fast read on flavor emulsion stability, showing that high absolute zeta alone isn’t enough if droplets approach or exceed 1 μm, where creaming risk rises.
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