Properties of bovine gelatin cross-linked by a mixture of two oxidases (horseradish peroxidase and glucose oxidase) and glucose

Abstract

ABSTRACTA mixture comprising horseradish peroxidase (HRP), glucose oxidase, and glucose was used to cross-link bovine gelatin via dityrosine formation. Suitable HRP, glucose oxidase, glucose addition levels, and reaction time were studied with single-factor trials, and selected as 100 U, 1 U, 0.025 mmol/g protein, and 3 h, respectively. Electrophoretic and circular dichroism analyses showed that the cross-linked gelatin contained high levels of polymerized proteins, had a typical triple helix structure at 5°C, but a more ordered secondary structure at 40°C. In comparison with bovine gelatin, the cross-linked gelatin had better colloidal stabilization in dispersion through the formation of aggregates of smaller hydrodynamic radius (73.3 versus 97.2 nm) and more negative zeta-potential (–8.15 versus –5.88 mV), showed enhanced thermal stability with a higher decomposition temperature (323.7°C versus 320.8°C), but less mass loss (50.10% versus 50.90%) and formed gels with shorter gelation time (14.1 versus 34.1 min) and stronger gel strength (increased by 12–14%).