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

peer reviewedFoaming-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. © 2020 Elsevier Lt

Enantioselective resolution of racemic styrene oxide at high concentration using recombinant Pichia pastoris expressing epoxide hydrolase of Rhodotorula glutinis in the presence of surfactant and glycerol

The reaction medium was optimized to accomplish epoxide hydrolase-catalyzed, batch enantioselective hydrolysis of racemic styrene oxide at high initial substrate concentrations. The recombinant Pichia pastoris containing the epoxide hydrolase gene of Rhodotorula glutinis was used as the biocatalyst. Enantiopure (S)-styrene oxide with 98% ee was obtained with 41% yield (maximum yield = 50%) from 1.8 M racemic styrene oxide at pH 8.0, 4 degrees C in the presence of 40% (v/v) Tween 20 and 5% (v/v) glycerol