Modified citrus pectins for improved emulsion stability 
Ulrike S. Schmidt1, Lea Koch2, Karsten Köhler1, Tomas Kurz2, 
H.-U. Endreß2, Heike P. Schuchmann1 
1Institute of Process Engineering in Life Sciences
Section I: Food Process Engineering/KIT, Karlsruhe/Germany
2Herbstreith&Fox KG Pektin-Fabriken, Neuenbürg/Germany

Pectins are natural hydrocolloids that have already been used as gelling agents and stabilizers within the food industry for a long time. The origin of their surface active properties, however, has not been fully understood yet. Only sugar beet pectin has been investigated deeper due to its protein moiety that is held responsible for its good emulsifying capacity. For industrial application, however, pectins from apple pomace and citrus peel are more relevant. Here, gelling properties can be controlled by esterification and amidation.
Pectins that combine both features – surface activity and good gelling properties – would give innovative possibilities to influence the structure of emulsions. Currently, we are investigating how chemical modification of citrus pectins is a suitable tool to create such functional pectins. 
Surface activity and gelling behavior of pectins are both important because these phenomena influence droplet breakup and subsequent stabilization in an emulsion. Interestingly, other solubilized substances also play an important role here and are able to significantly influence the formed emulsion structure. Therefore, it is not enough to only investigate the “emulsifying capacity”. We characterize modified pectins by distinguishing between molecule features responsible for oil droplet breakup and for short and long term stabilization of the formed emulsion. Through this approach, correlations between pectin structure and emulsion characteristics can be drawn and it will be possible to choose specific pectins according to particular emulsion requirements.