Asymmetric flow field flow fractionation for the investigation of caseins cross-linked by microbial transglutaminase. (July 2019)

• Record Type: Journal Article
• Authors: Abbate, Raffaele Andrea; Raak, Norbert; Boye, Susanne; Janke, Andreas; Rohm, Harald; Jaros, Doris; Lederer, Albena
• Is Part Of: Food hydrocolloids. Volume 92(2019)
• Page Start: 117
• Page End: 124
• Publication Date: 2019-07
• Subjects: Casein -- Cross-linking -- Microbial transglutaminase -- Asymmetric flow field flow fractionation -- Light scattering -- Scaling properties; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2019.01.043
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: The cross-linking of caseins with microbial transglutaminase (mTGase) was investigated using asymmetric flow field flow fractionation in combination with static and dynamic light scattering detections (AF4-MALS-DLS). This approach allows determining molar mass, molecular size, scaling properties, and apparent densities of casein aggregates prior to and after enzymatic treatment. The results show that, as a consequence of non-covalent interactions, casein molecules associate to form elongated aggregates with a molar mass ( M w ) ranging from approx. 4 × 10 5 to 1.2 × 10 6 g mol −1, and a mean radius of gyration ( R g, z ) of approx. 16 nm. Upon enzymatic treatment with mTGase, casein aggregates become more compact as M w increases but R g decreases with ongoing cross-linking reaction. In contrast, the hydrodynamic radius ( R h ) distribution determined by online DLS is rather unaffected by enzymatic cross-linking, indicating that mTGase cross-links casein molecules mainly within distinct aggregates. Furthermore, extensive enzymatic treatments with mTGase change the molecular shapes of casein aggregates towards more compact and denser spherical structures. Graphical abstract: Image 1 Highlights: Casein cross-linking studied by asymmetric flow field flow fractionation and light scattering. Casein molecules associate to form elongated aggregates. Enzymatic treatment leads to compact casein aggregates with the incubation time.