Development of an objective image analysis test for the measurement of dairy powder dispersibility

Dispersibility is a very important ‘instant’ characteristic of a consumer milk powder. Traditional methods for assessing dispersibility often involve a standardised manual reconstitution step followed by sieving through a mesh and subjective visual comparison of the sludge on the mesh against photographic standards. A new approach for quantifying dispersibility by measuring the undispersed sludge remaining in the bottom of the vessel after a standardised reconstitution process is introduced in this study. Using a mechanical mixer combined with image analysis, this method offers a rapid, objective, reproducible and consumer-relevant assessment of milk powder dispersibility and enhances differentiation between milk powders, enabling more precise monitoring of powder functionality and quality control. Additionally, the relationship between the size and shape of whole milk powder agglomerates and their dispersibility was explored. A clear correlation between increased agglomerate size and improved dispersibility was obtained, indicating that particle size analysis could be used as a proxy for dispersibility testing.