Modelling the reactions between free phenols, vitamin C, apple polyphenoloxidase and oxygen during a thermal treatment

Jean-Pierre Aka (1, 2, 3, 4, 5) , Francis F. Courtois (6) , Loïc Louarme (6) , Jacques Nicolas (6) , Catherine Billaud (1, 2, 3, 4, 5)

1 GENIAL - Génie industriel alimentaire
2 INRA - Institut National de la Recherche Agronomique
3 AgroParisTech
4 Ecole Nationale Supérieure des Industries Agricoles et Alimentaires
5 CEMAGREF - Centre national du machinisme agricole, du génie rural, des eaux et forêts
6 GENIAL - Ingénierie Procédés Aliments

The kinetics of degradation of chlorogenic acid, epicatechin, L-ascorbic acid and of

polyphenoloxidase activity from some apple in malate buffer (pH 3.8) solutions at 20 and 50 °C

with oxygen were investigated to provide information on the impact of the presence of

chlorogenic acid, epicatechin and/or L-ascorbic acid on polyphenoloxidase thermostability but

also the effect of the heat treatment on their degradation both by enzymatic and nonenzymatic

ways. Stoechiokinetic reactions on the basis of experimental data and literature and

determination of the kinetic constants at 20 and 50 °C were elaborated before modelling the

interaction among reactants, by fitting the reaction curves to predictive model. Apple

polyphenoloxidase was thermolabile, as total denaturation occurred after 10 min at 70 °C and

only 3 min at 80 °C. Losses of polyphenoloxidase activity at 20 and 50 °C were favored by the

presence of epicatechin in model solutions, compared with chlorogenic acid, due to the

formation of quinones of epicatechin that diminished polyphenoloxidase stability. Temperature

quickened both enzymatic phenol oxidation before polyphenoloxidase deteriorated and the

whole set of the chemical reactions, including the production of secondary oxidation products

and chlorogenic acid or epicatechin regeneration. The results obtained by simulation of the

model fittings to experimental data also confirmed that L-ascorbic acid in excess induced a fast

regeneration of chlorogenic acid and epicatechin from quinones of chlorogenic acid and

quinones of epicatechin formed enzymatically via redox chemical reactions.

Keywords: modelling, reactions, thermal treatment, oxidation

Domaines: Sciences du Vivant [q-bio]

Jean-Pierre Aka, Francis F. Courtois, Loïc Louarme, Jacques Nicolas, Catherine Billaud. Modelling the reactions between free phenols, vitamin C, apple polyphenoloxidase and oxygen during a thermal treatment. EFFOST Annual Conference, 1992, Montpellier, France. ⟨hal-01595213⟩