Eugenol emulsions affect the browning processes, and microbial and chemical qualities of fresh-cut Chinese water chestnut

The browning inhibition and preservation properties of eugenol emulsions (EUG) on fresh-cut Chinese water chestnut (CWC), and the associated mechanisms of browning inhibition were studied in relation to enzymatic activities and polyphenol substrates. Fresh-cut CWC was treated with different concentrations of EUG, resulting in the maintenance of quality, inhibition of the microbial index which decreased by 1.20 log CFU/g after storage and enzymatic activities of different enzymes such as polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase (PAL). Correlation analysis between enzymatic activities and degree of browning suggested that PAL was the main enzyme that led to browning in fresh-cut CWC. The enzymatic activity of PAL was decreased by 57% with the 1.5% EUG treatment after 12 d of storage. HPLC analysis showed that EUG-treated fresh-cut CWC (1.5%) slightly changed 5 phenolics during storage and the EUG content decreased from 32.8 to 13.0 mg/kg in treated groups. The potential mechanism is that EUG could inhibit the browning of CWC by reducing the enzymatic activities especially PAL, and decreasing the changes in phenolic content.