Effect of carbon monoxide on browning of fresh-cut lotus root slice in relation to phenolic metabolism

The effect of carbon monoxide (CO) on enzymatic browning of fresh-cut lotus root slices in relation to phenolic metabolism was investigated. Fresh-cut lotus root slices were fumigated with CO gas at 75, 125, 175 or 225 mu L/L for 10, 20, 30 or 40 min, and then stored for 8 days at 5 degrees C. Changes in color, total phenol, malonaldehyde (MDA), and activities of phenolic-associated enzymes including polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonialyase (PAL) in lotus root slices were measured. The results indicated that fumigating fresh-cut lotus root slices with 175 mu L/L of CO for 20 min delayed browning and inhibited increase of MDA. Besides, total phenol also showed higher level from 0 to 4 days. Furthermore, the activities of PPO and POD were inhibited, but PAL activity was increased. The present data suggests that CO has the potential to inhibit browning and maintain quality of fresh-cut lotus root slices. (C) 2013 Elsevier Ltd. All rights reserved.