In-situ rheological and structural characterization of milk foams in a commercial foaming device

Processing, stability and sensorial perception of food foams are tightly related to their microstructure and flow behavior. Characterization of corresponding physical parameters is central for product development and quality control. An experimental setup enabling in-situ characterization of yield stress, gas volume fraction and bubble size distribution at different heights within a foam column created in a commercial whipping device is presented. Reliable determination of these quantities is shown. Foams made from regular and reconstituted milk have been investigated. Gas volume fraction and bubble size increase monotonically during free drainage. Related to the changes in these parameters, the yield stress increases strongly during initial drainage and weaker in mature foams. Gradients of the structural and rheological parameters along the direction of gravity increase over time. Yield stresses in these milk foams are as predicted from phenomenological modelling including the above parameters, emphasizing the reliability of the measurement setup.

Automated summary

The study presented an experimental setup for in-situ characterization of physical parameters of food foams, showing reliable determination of yield stress, gas volume fraction, and bubble size distribution at different heights. It was found that the gas volume fraction and bubble size increase monotonically during free drainage, and gradients of structural and rheological parameters along the direction of gravity increase over time. The yield stresses in milk foams were as predicted from phenomenological modeling, emphasizing the reliability of the measurement setup.