Cross-linking with microbial transglutaminase: Relationship between polymerisation degree and stiffness of acid casein gels

Jaros, Doris; Schwarzenbolz, Uwe; Raak, Norbert; Löbner, Jürgen; Henle, Thomas; Rohm, Harald

doi:10.1016/j.idairyj.2013.10.011

Cited by 32 publications

(20 citation statements)

References 15 publications

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“…Peptide bonds between terminal functional groups, referred to as isopeptide bonds, are not susceptible to most proteolytic enzymes and remain therefore intact after total enzymatic protein hydrolysis; subsequent amino acid analysis by chromatographic techniques enables the determination of the N-ε-(γ-glutamyl)-lysine isopeptide [29]. Although the isopeptide content was shown to be an important driver for the stiffness of acid-induced casein gels, polymer size still has to be taken into account [30][31][32]. Besides TGase, oxidoreductases were applied, which have a completely different cross-linking mechanism: firstly, the enzymes oxidise specific functional groups that react further in non-enzymatic reactions.…”

Section: Cross-linking Enzymesmentioning

confidence: 99%

“…This leads to a variety of covalent bonds so that the total number of cross-links can hardly be determined by amino acid analysis [23]. Monogioudi et al [33] applied 31 P nuclear magnetic resonance spectroscopy after phosphorylation of hydroxyl groups to quantify cross-links formed in β-casein after oxidation of tyrosine residues by tyrosinase (EC 1.14.18.1). Recently, cross-linking with laccase (EC 1.10.3.2) was tested for its potential to improve the structure of stirred yoghurt gels in a post-fermentation step because of the acidic pH optimum of the enzyme.…”

Section: Cross-linking Enzymesmentioning

confidence: 99%

“…Such buffers frequently contain urea [30,53,89,91,131], SDS [115,132], or guanidine hydrochloride [116]. Using non-denaturing buffers for studying sodium caseinate has been reported to result in an additional high molecular weight fraction composed of mainly non-covalently associated aggregates [89,133].…”

Section: Separation Principlementioning

confidence: 99%

“…SEC column materials differ in composition and pore volume. The column most frequently used for studying cross-linked casein is Superdex 200, e.g., [30,44,47,48,54,100,115,131,[134][135][136][137][138][139][140][141][142][143][144][145][146][147][148], which is provided by GE Healthcare (Uppsala, Sweden). The column material is based on agarose/dextran with a ratio of pore volume to void volume of V i /V o = 1.7 and exhibits a fractionation range from 10 to 600 kg/mol for globular proteins [128].…”

Section: Separation Principlementioning

confidence: 99%

“…For instance, the highest number of casein dimers in TGase-catalysed polymerisation was observed in moderately cross-linked samples, i.e., at high levels of residual monomers (>50%), indicating that dimers as well as smaller oligomers are good substrates for further cross-linking by TGase [32,78,146]. Moreover, the polymerisation degree (sometimes also referred to as oligomerisation degree) was calculated in several studies from size exclusion chromatograms by relating peak areas of cross-linked caseins to the entire sample area [30,32,44,47,48,53,78,[134][135][136][146][147][148]. Because reference casein samples often reveal a low level of polymerised casein (see Figures 9 and 10), the polymerisation degree after cross-linking was also expressed as the difference between cross-linked samples and reference [137][138][139]144,145].…”

Section: Literature Review Of Studies On Cross-linked Caseinmentioning

confidence: 99%

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Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their Applications

et al. 2018

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Abstract:Casein is the major protein fraction in milk, and its cross-linking has been a topic of scientific interest for many years. Enzymatic cross-linking has huge potential to modify relevant techno-functional properties of casein, whereas non-enzymatic cross-linking occurs naturally during the storage and processing of milk and dairy products. Two size separation techniques were applied for characterisation of these reactions: gel electrophoresis and size exclusion chromatography. This review summarises their separation principles and discusses the outcome of studies on cross-linked casein from the last~20 years. Both methods, however, show limitations concerning separation range and are applied mainly under denaturing and reducing conditions. In contrast, field flow fractionation has a broad separation range and can be easily applied under native conditions. Although this method has become a powerful tool in polymer and nanoparticle analysis and was used in few studies on casein micelles, it has not yet been applied to investigate cross-linked casein. Finally, the principles and requirements for absolute molar mass determination are reviewed, which will be of increased interest in the future since suitable calibration substances for casein polymers are scarce.

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