Effects of Blanching on the Activities of PPO, POD and PAL from Artemisia Selengensis

摘要

After leaf removed, pre-cooled and washed, Artemisia Selengensis stems were cut into the length of 2.5 -3.5 mm. The cut products then put into plastic bags and stored at 40C for later use. The activities of polyphenolic oxidase (PPO), peroxidase (POD), and phenyl-alanine ammonia lyase (PAL) extracted from Artemisia Selengensis stems were measured after blanching at the temperature of 85. 0°C, 90.0°C, 95. 0°C and 100.0°C for 1.0, 2.0, 3.0, and 5.0 min, respectively. The main results were as following: The activity of PPO from Artemisia Selengensis was extremely high before blanching (could be as high as 1200u/gFW), and dramatically decreased after blanching at all temperatures. More activity was lost with the increase of treated temperature and tune and there was almost no PPO activity existed after the treatment of 95.0°C for 1 min. 2 min or more blanching duration, no matter what temperature it is, all resulted in PPO activity close to zero. POD from Artemisia Selengensis was more sensitive than PPO for blanching temperature and there was almost no residual activity left at 85.0°C for 1 min. The activity of PAL from Artemisia Selengensis at blanching temperature of 85.0°C could be strongly inhibited (up to 95 -97% ) but could not be completely inactivated. With the temperature increase from 85.0°C to 95.0°C, PAL also increased somewhat, and then decreased with the farther increase of temperature. After treated with 100. 0°C, 5.0 min, there was still 1.5% PAL activity left in the tissue.