Study On Inhibition Of Enzymatic Browning Of Potatoes By Proline Treatment Before Cutting

With the development of the domestic market of fresh-cut product,the demand for fresh-cut potatoes is also increasing.However,the enzymatic browning of fresh-cut potatoes seriously affects the value of their products and shortens their shelf life.At present,there is no safe and effective method to inhibit the browning of fresh-cut potatoes.Previous studies have shown that under stress,plants accumulate osmotic substances,proline,which can maintain the plant's redox balance,protect the plant's antioxidant system,and improve its antioxidant capacity.Therefore,it is speculated that proline treatment possibly inhibits the enzymatic browning of potatoes.The previous research in our laboratory showed that post-cut proline treatment can not retard the browing.In this experiment,a new technique for inhibiting browning of fresh-cut potatoes was developed by using pre-cut proline treatment of Holland15 potato as experimental material.The preliminary mechanism of proline inhibiting the browning was elucidated by investigating the browning related enzyme activity,substrate and anti-oxidation ability The results are as follows:(1)Proline treatment before cutting can effectively inhibit the browning of fresh-cut potato chips and potato pulp.According to the screening of the proline solution concentration,soaking time and soaking temperature before cutting,it is concluded that the browning control effect is best when treated in a 90 mmol / L proline solution at 30? for 1 h.Potato slices treated under this condition were slightly browning after 4 d storage in a cold storage at 2 to 5?and still had commercial value.In contrast,control slices were moderately browning after 12 hours of storage and lost commercial value.The technique is simple to be operated,safe and hygienic,and suitable for industrial production.(2)By measuring the activities of PPO,POD,CAT and antioxidant capacity of potato pulps and potato slices,it was found that pre-cut proline treatment can significantly reduce the PPO activity of potato slices and pulps;increase the CAT activity during browning,but for POD no significant influence on activity.Proline treatment before cutting improved the total antioxidant capacity of fresh-cut potato chips,but only increased the FRAP and ABTS free radical scavenging rate of potato slurry,and had no significant effect on the DPPH free radical scavenging rate of the slurry.It is speculated that pre-cut proline treatment delays the browning of fresh-cut potato slices,which is related to inhibiting the activity of PPO,increasing the activity of CAT,accelerating the decomposition of hydrogen peroxide in potato,and preventing the excessive accumulation of hydrogen peroxide from harming cell membranes.By measuring endogenous proline in potato,it was found that pre-cut proline treatment can increase the endogenous proline content in potato.(3)By measuring the content of enzymatic browning substrate-tyrosine and total phenol in potato,it was found that pre-cut treatment of proline can significantly reduce the content of tyrosine and total phenol in potato.It is speculated that pre-cut treatment of proline can reduce the browning by decreasing the content of potato browning substrate.