The optimum pretreated times of citric acid were 18 h and 24 h,vitamin C and polyvinylpyrrolidone (PVP) was 3 h.

• 结果表明,柠檬酸的适宜处理时间为18h和24h,抗坏血酸(VC)和聚乙烯吡咯烷酮(PVP)的适宜处理时间均为3h;