Determination of phenol extracted and the characteristics of peroxidase from fresh-cut Zizania latifolia

The phenols of Zizania latifolia were determined by combination of effect of acid and base, scanning spectrum and high performance liquid chromatography (HPLC) , and the characteristics of POD in fresh-cut Z.latifolia were investigated.The results showed that the main phenols of fresh-cut Z.latifolia were gallic acid and caffeic acid, which accounted for 25.57% and 29.54%, respectively, of the total content of Z.latifolia phenol extracts.Both phenols could be used as substrate for the fresh-cut Z.latifolia POD, while caffeic acid also was the precursor substance of lignin synthesis, indicating that fresh-cut Z.latifolia not only had very strong browning potential, but also had the material base of rapid lignification.The POD activity in fresh-cut Z.latifolia was very high.POD had greatest activity at pH6.0 and temperature 40.0℃, and lost activity quickly when pH below 5.0 or temperature above 60℃.The POD activity increased fast when H2O2 was below 12.25 mmol/L, and increased a little afterwards, reached the maximum at the H2O2 level of 14.71 mmol/L, then decreased.The Km for pyrogallic acid, caffeic acid, guaiacol, epicatechin, catechol, gallic acid, tyrosine, cinnamic acid and H2O2 were 1.75, 5, 12, 16, 41.5, 76.2, ∞, ∞ and 4.91mmol/L, respectively.The POD showed the highest activity when combined with guaiacol.