Effects of laccase from Botrytis cinerea on the oxidative degradation kinetics of the five natural grape anthocyanins
Enzymatic browning is an oxidation process that occurs in many foods that increases the brown colour. This problem is especially harmful in the wine industry. especially when the grapes are infected by grey rot since this fung release the oxidative enzyme laccase. In the particular case of red wines, the presence of laccase implies the deterioration of the red colour and can even cause the precipitation of the coloring matter (oxidasic haze). The aim of this work was to study the degradation kinetics of the five grape anthocyanins by laccase from Botrytis cinerea. In individual solution, the three anthocyanins with 3 substituents in the B-ring: petunidin, delphinidin and malvidin were degraded much faster than those of 2 substituents, cyanidin and especially peonidin that is even not degraded by laccase. In contrast, in an equimolar solution of the 5 anthocyanins, the degradation kinetics of all anthocyanins was more similar and all of them, even peonidin were degraded. This different kinetics behavior of the five anthocyanins when they are alone or in mixture may be probably due to the fact that, after the formation of the primary quinones, chemical polymerization occurs with other phenols without the action of laccase. Consequently, the less reactive anthocyanins, such as peonidin and cyanidin 3-O-glucosides, can be used to form polymers without the action of laccase. This effect would probably also occur in the presence of other phenols, which could generate insoluble polymers that would cause oxidasic haze.
Acknowledgements: This research was funded by CICYT project RTI2018-095658-B-C33.
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Issue: ICGWS 2023
1Departament de Bioquímica i Biotecnologia, Facultat d’Enologia de Tarragona, Universitat Rovira i Virgili, C/Marcel.li Domingo s/n, 43007 Tarragona, Spain