Limited changes in physical and rheological properties of peroxidase-cross-linked apo-alpha-lactalbumin after heat treatment

作者：Saricay Yunus^*; Wierenga Peter A; de Vries Renko

来源：Food Hydrocolloids, 2017, 66: 326-333.

DOI：10.1016/j.foodhyd.2016.11.045

• Stability
• Heat treatment
• Enzymatic cross-linking
• Peroxidase
• alpha-lactalbumin
• Whey proteins

The current study aims at elucidating the effect of heating on the physical properties of peroxidase-crosslinked (apo) alpha-lactalbumin (alpha-LA) aggregates with hydrodynamic radii (R-H) of 25 nm - 100 nm. We consider the effects of heating at the single protein level, and at the particle level for both dilute and dense dispersions of the cross-linked alpha-LA. From far-UV circular dichroism (CD) spectroscopy, we find that changes in the secondary structure of the cross-linked alpha-LA are limited upon heating but thermoreversible. Cross-linking already leads to a complete disappearance of all tertiary structure, and heating therefore leads to no further changes of tertiary structure as detected by near-UV CD. The surface hydrophobicity of the cross-linked alpha-LA, as probed using a fluorometric assay (ANSA), remains unchanged upon heating, whereas heating leads to a significant increase of surface hydrophobicity for uncross-linked alpha-LA. Prolonged heating leads to a moderate decrease of the particle size of alpha-LA aggregates, while heating does not affect its electrophoretic mobility. As a consequence of the insensitivity of the physical properties of the cross-linked alpha-LA to heating, we find that dilute dispersions of the cross linked alpha-LA are stable against heat-induced aggregation over a wide range of pH values and salt concentrations. Furthermore, for dense dispersions of alpha-LA aggregates, that form physical hydrogels, we find that heating has a very limited impact on the rheology of the hydrogels. Our results may be of importance in designing heat-insensitive protein ingredients for novel food formulations.

• 出版日期2017-5