Effect of Blanching Treatments on the Quality of Fresh-cut Root Vegetables

The effects of hot water blanching and steam blanching (100℃, treatment time 5 s, 10 s, 15 s, 20 s) on polyphenol oxidase (PPO)activity and browning degree (BD) in fresh cut potato, lotus root and white radish were studied. The main experimental results are as follows: Both blanching methods can effectively inhibit browning of three fresh cut vegetables. However, the inactivation of steam blanching on the PPO activity was more effective than that of hot water blanching. After 15 seconds of steam blanching, the residual PPO activity was below 30%, but residual PPO activity was still above 50% after 20 s of hot water blanching for 20 s. During storage, the hardness of the three fresh cut vegetables was decreased while the microorganism and total color difference were increased with increasing storage time. At 7 d, the hardness of radish decreased by 23.3%. The number of microorganisms in lotus root increased by 1.75 logarithms. The total color difference of potatoes ΔE increased the most, to 33.49. These results show that steam blanching can effectively inhibit browning and keep the quality the three fresh cut vegetables.