Development of a synthetic model to study browning caused by laccase activity from Botrytis cinerea

The aim of this paper is to develop a synthetic model reproducing more realistically the conditions of grape juice to study browning caused by laccase from Botrytis cinerea. The laccase browning kinetics were measured by monitoring the increase in absorbance at 420 nm over time in the presence of different substrates - one monophenol: 4-hydroxybenzoic acid; three orthodiphenols: caftaric acid, (+)-catechin and (-)-epicatechin; and one triphenol: gallic acid. The results indicate that orthodiphenols are better substrates than triphenols and that monophenols do not appear to be reactive. Of the orthodiphenols, (+)-catechin showed the greatest browning intensity, followed in decreasing order by (-)-epicatechin and caftaric acid. These results confirm that sulfur dioxide, ascorbic acid and glutathione really do protect grape juice against laccase browning. The effectiveness of ascorbic acid and glutathione also confirm that both antioxidants can be useful tools for reducing doses of sulfur dioxide in winemaking, especially when grey rot is present.

Automated summary

This study aimed to develop a synthetic model to realistically study browning in grape juice caused by laccase from Botrytis cinerea. The research found that orthodiphenols are better substrates for the reaction, while monophenols do not seem to be reactive. Additionally, the effectiveness of ascorbic acid and glutathione in protecting grape juice against laccase browning suggests they can be useful tools to reduce sulfur dioxide doses in winemaking, especially when grey rot is present.