Turbidity in oil-in-water-emulsions - Key factors and visual perception

Area of Science:

• Food Science
• Colloid and Surface Science
• Sensory Science

Background:

• Turbidity is a critical visual attribute in beverage emulsions, influencing consumer acceptance.
• Understanding the factors affecting turbidity and human perception is essential for product development and quality control.

Purpose of the Study:

• To systematically identify factors influencing turbidity in beverage emulsions.
• To investigate the relationship between physical parameters and the visual perception of turbidity.
• To provide insights for tailoring turbidity in product development and quality control.

Main Methods:

• Sensory evaluation of human visual perception of turbidity across a range of nephelometric turbidity units (NTU).
• Analysis of key physical parameters including particle size (mean volume-surface diameter), refractive index, aqueous phase composition, and emulsifier concentration.
• Correlation of physical parameters with measured turbidity levels.

Main Results:

• Human visual sensitivity to turbidity differences is highest between 1000 and 1500 NTU.
• Distinguishing significantly different turbidity levels required values >2000 NTU.
• Oil droplet particle size was the most significant factor, with maximum turbidity observed at a mean volume-surface diameter of 0.2μm.
• Changes in the oil phase's refractive index could alter turbidity by up to 30% in typical beverage emulsions.
• Aqueous phase composition and excess emulsifier presence also influenced turbidity.

Conclusions:

• Turbidity in beverage emulsions is controllable through manipulation of particle size, refractive index, and formulation.
• Knowledge of human visual perception thresholds allows for precise control of optical appearance.
• This study provides a framework for optimizing turbidity in beverage product development and ensuring consistent quality.