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Inactivation of polyphenol oxidase by pulsed light
1 , 1 , 1 , * 2
1  Departamento de Ciencia y Tecnología de Alimentos, Universidad Católica de Murcia (UCAM), Campus de los Jerónimos 135, Guadalupe 30107, Murcia, Spain.
2  Green and Innovative Technologies for Food, Environment and Bioengineering Research Group ( FEnBeT) UCAM Universidad Católica San Antonio de Murcia Campus de los Jerónimos 135, Guadalupe 30107, Murcia, Spain
Academic Editor: Diego Moreno-Fernandez

https://doi.org/10.3390/Foods2021-11079 (registering DOI)
Abstract:

Pulsed light (PL) is a novel technology based on heating a xenon lamp with a high-voltage current to generate a broadband light emission with an important UV component. This high-voltage does not require extreme electricity consumption because it is produced thanks to the use of capacitors that store electricity from the main during relatively long times and are discharged to the lamp in very short times. The kinetics of polyphenol oxidase (PPO) inactivation by this technology was measured and some associated structural changes were investigated by fluorometry and spectrophotometry in order to gain insight into the inactivation mechanism. To this, residual activity, tryptophan fluorescence, KI fluorescence quenching and turbidity were measured. The inactivation followed the Weibull model. The decrease in tryptophan fluorescence and the increase in Stern-Volmer constant with the progress of the PL treatment indicate the unfolding of the enzyme; a constant turbidity indicates no aggregation. The Trp fluorescence phase-diagram shows no evidence of intermediates. Therefore, these results support the idea that PL inactivates PPO by modifying its tertiary structure in an all-or-none process.

Keywords: Pulsed light; novel technologies; polyphenol oxidase; enzyme inactivation; enzyme structure; fluorescence spectroscopy

 
 
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