Abstract:

In order to study the effects of peroxidase（POD）on browning of Agaricus bisporus，the POD enzymatic characteristics and the relationship of POD activity and browning were analyzed. Results showed that the Michaelis constant Km of POD was 5.704 mmol ? L-1，and the appropriate pH and reaction temperature were 5.0 and 45 ℃，respectively，under the condition of guaiacol as the substrate. Low temperature could significantly inhibit POD activity，the relative activities of POD at 20 ℃ and 10 ℃ were 68% and 55%，respectively，while there was no significant difference of POD activities from 2 ℃ to 10 ℃. Compared with 10 ℃，the POD activities of Agaricus bisporus under 20 ℃ at 1 and 2 d were increased by 4.8 and 10.9 fold，respectively. Dithiothreitol（DTT）had the strongest inhibition on POD activity，followed by ascorbic acid（AsA），L-cysteine（L-Cys），sodium lauryl sulfate（SDS），anhydrous sodium sulfite，citric acid and NaCl. During storage，there was no significant difference in the browning degree between Agaricus bisporus treated by inhibitor and controlled atmospheres，while POD activity of Agaricus bisporus treated by inhibitor was much higher，which indicated that high POD activity was not the main factor for Agaricus bisporus browning.

Key words: Agaricus bisporus, peroxidase, enzymatic characteristic, storage