文摘
This study aimed to investigate the profiles change in proanthocyanidins (PAs) catalyzed by polyphenol oxidase (PPO) from lotus seedpod in a model wine system (MWS). Results showed that PAs from lotus seedpod consisted of dimer (74.00?%) and trimer (22.75?%). PPO could tolerate ethanol concentrations below 20?% (v/v). The optimum temperature of PPO activity was 80?°C, and the optimal pH was 9.0. Its molecular weight was approximately 31?kDa, and its secondary structures were α-helix (59.0?%), β-sheet (4.3?%), turns (14.1?%), and random coils (22.6?%). In the MWS, the trimers gradually increased from 22.55?% at 0?h (control) to 100?% at 10?h incubation, while the dimers decreased from 74.33?% (control) to 0?% at 10?h incubation. Moreover, the composition of the precipitate formed at different incubation time points was approximately 16.54?% of monomers, 21.03?% of dimers, and 62.43?% of trimers at 2?h incubation with PPO. The results from this study have provided in vitro evidence for a possible application of PPO in red wine aging.