Acid gelation of enzymatically cross-linked casein: from molecular level to network formation

Caseins (80 % of protein fraction in milk) contribute essentially to structure formation in fermented milk products (yoghurt, cheese). This can be significantly influenced through an enzymatic cross-linking of casein by microbial transglutaminse. However, the enzyme's modus operandi is still poorly understood, which makes its controlled application in the milk industry difficult.

We aim to analyse the structure-function-interaction of enzymatically cross-linked casein on different length scales. For this, casein of various structural conformations is generated through the environmental conditions, and subsequently cross-linked by microbial transglutaminase. Finally, we investigate physico-chemical properties and gelation of the casein, which will be correlated to the casein's structure.

In cooperation with:

Leibniz-Institut für Polymerforschung Dresden e.V., Polymer Separation Group (PD Dr. Albena Lederer)

Supported by:

Deutsche Forschungsgemeinschaft

Project publications:

Raak N, Rohm H, Jaros D (2017) Enzymatic cross-linking of casein facilitates gel structure weakening induced by overacidification. Food Biophysics 12, 261-268.

Raak N, Rohm H, Jaros D (2017) Cross-linking with microbial transglutaminase:
Isopeptide bonds and polymer size as drivers for acid casein gel stiffness. International Dairy Journal 66, 49-55.

Raak N, Abbate RA, Lederer A, Rohm H, Jaros D (2018) Size separation techniques for the characterisation of cross-linked casein: A review of methods and their applications. Separations 5, 14

Raak N, Schöne C, Rohm H, Jaros D (2019) Acid-induced gelation of enzymatically cross-linked caseinate in different ionic milieus. Food Hydrocolloids 86, 43-49.

Raak N, Brehm L, Abbate RA, Henle T, Lederer A, Rohm H, Jaros D (2019) Self association of casein studied using enzymatic cross-linking at different temperatures. Food Bioscience 28, 89-98.

Abbate RA, Raak N, Boye S, Janke A, Rohm H, Jaros D, Lederer A (2019) Asymmetric flow field flow fractionation for the investigation of caseins cross-linked by microbial transglutaminase. Food Hydrocolloids 92, 117-124.

Raak N, Brehm L, Leidner R, Henle T, Rohm H, Jaros D (2019) Hydrolysis by indigenous plasmin: Consequences for enzymatic cross-linking and acid-induced gel formation of non-micellar casein. Food Biophysics, doi: 10.1007/s11483-019-09601-2

Project researchers and contact: