Molecular and air-water interfacial properties of potato protein upon modification via laccase-catalyzed cross-linking and conjugation with sugar beet pectin

Abstract

Foaming-related functionalities of potato proteins are important for the development of innovative food products. The main purpose of current study was to investigate the effects of laccase-catalyzed modifications on the tertiary structural property, the thermal property, the air-water interfacial adsorption kinetics and the film rheological characteristics of potato protein at selected pH values. The cross-linking of potato protein (PPT) with or without the presence of ferulic acid (FA) as mediator and its conjugation with sugar beet pectin were biocatalyzed by fungal laccases (Trametes versicolor or Coriolus hirsutus). As compared to the native potato protein, all modified proteins were unfolded, and a decrease in the structural compactness was observed. The conjugation of potato protein with sugar beet pectin (PPT-SBP-H/-L) exhibited stabilization effect against unfolding and heating, which also promoted the adsorption of potato protein, while the cross-linked potato proteins (MPPT24h, MPPT24hFA) contributed to high surface dilatational elasticity of the interface, at neutral pH condition. The extended laccase-cross-linking treatment (MPPT48h, MPPT48hFA) resulted in a higher structural stability of the proteins than the other modified ones. At acidic pH conditions, these protein samples exhibited relatively high surface dilatational moduli. This study provided insights into the impact of laccase-catalyzed modifications on the functionalities of potato protein from molecular and mesoscopic aspects.