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This study aimed to determine the stability of PCs in grape canes extracts stored at different temperatures and light conditions. The PCs composition was monitored every-two weeks during three months by liquid chromatography coupled to diode array and fluorescence detectors (LC-DAD-FLD). Initially, stilbenes represented 87 % of total PCs. Storage at -20 and 5 °C reduced PCs 8 and 6 %, respectively. When extracts were exposed to 25 and 40 °C, the degradation of (+)-catechin and (-)-epicatechin was faster than under lower temperatures, and light accelerated the degradation kinetics. trans-piceatannol showed particularly sensitive to temperature increase, being mostly degraded after two weeks stored at 40 °C. Conversely, degradation of trans-resveratrol and ε-viniferin was mostly catalyzed by light, since nearly 70 % of them were degraded at 40 °C under light, in comparison with a 23 % reduction of trans-resveratrol and no changes of ε-viniferin at 40 °C in darkness. |
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