Use of different food additives to control browning in fresh-cut potatoes

Fresh-cut potato browning is a severe problem in the potato processing industry. Ascorbic acid, L-cysteine, hydrogen sulfide (H₂S), and nitric oxide (NO) have been reported to reduce the browning in fresh-cut vegetables and fruits. We compared the effect of each food additive at its commonly used concentration on fresh-cut potato browning in order to choose a highly efficient treatment and explore its mechanism. Fresh-cut potato slices were immersed in 0.3 mmol L^-1 ascorbic acid, 0.7 mmol L^-1 L-cysteine, 0.7 mmol L^-1 H₂S, or 2.0 mmol L^-1 NO for 10 min and stored at 4°C until the measurements finished. Results showed that the ascorbic acid and L-cysteine treatments showed less browning than the control treatment, while the H₂S and NO treatments did not. Ascorbic acid increased total phenolic content, polyphenol oxidase (PPO) and peroxidase (POD) activities, while L-cysteine decreased PPO and POD activities with no change in total phenolic content. In addition, these two treatments did not influence respiration rate, weight loss, or rot index. In conclusion, ascorbic acid (0.3 mmol L^-1) and L-cysteine (0.7 mmol L^-1) can be valuable means to control fresh-cut potato browning. Ascorbic acid inhibits the browning mainly by reducing quinones back to phenolic compounds, but L-cysteine inhibits the browning mainly by decreasing PPO and POD activities.