Effects of pulsed electric field treatment on (+)-catechin–acetaldehyde condensation

Abstract

Condensation of (+)-catechin contributes significantly to wine taste during its aging process. In order to simulate and explore a feasible method to enhance conversion of proanthocyanidins (PAs), the effect of pulsed electric field (PEF) treatment on the condensation efficiency between (+)-catechin and acetaldehyde in a wine model solution was investigated in this paper. The PEF intensity used ranged from 0 to 50 kV/cm. The content of (+)-catechin was monitored by HPLC–PAD. Results showed that the condensation reaction between (+)-catechin and acetaldehyde was enhanced by PEF treatment. The (+)-catechin decrease rate had an obvious increase with increasing PEF intensity. Furthermore, it increased with reaction temperature, as well as with decreasing pH values under PEF treatment (40 kV/cm). It was observed that the content of (+)-catechin after reaction for 31.12 ms under 40 kV/cm was approximately equivalent to that after reaction for 62.23 ms without PEF treatment. In addition, it was demonstrated that activation energy (Ea) of the condensation reaction was reduced remarkably by PEF treatment (from 41.59 kJ/mol to 28.98 kJ/mol under 40 kV/cm). Moreover, mass spectrometry analysis showed that both the reactions with and without PEF treatment fit the same pathway, indicating no change in reaction products. Future work will focus on the studies of changes of pH in the treatment chamber to verify the reaction mechanism. This study showed that pulsed electric field treatment (PEF) could be a novel and promising technology for the wine industry to accelerate the condensation between (+)-catechins, thus improving the quality of wine in a short time.