Critical consideration of gas bubbles to replace fat globules in acidified milk matrices

Abstract

The influence of low gas volume fraction and bubble deformability on rheological properties and microstructure of acidified milk matrices was investigated; functionality was compared with that of fat globules. With increasing fat volume fraction, stiffness and yield stress of the acidified milk models increased, but decreased with increasing gas volume fraction. This was caused by the large size of the bubbles compared with the fat globules and different processing of the samples containing gas and fat, respectively. A mixture of 1% fat together with gas bubbles resulted in a smaller mean bubble size and thus stiffer bubbles. Simultaneously, an increase in stiffness and yield stress of the bubble-containing matrices was observed, although not to the same extent as for unfoamed matrices with increasing fat content. Beyond a critical gas volume fraction of 0.27, gas bubbles were no longer separated and interacted with other matrix components and themselves, weakening the structure.