Carrots have symptoms of oxidative surface browing ( Chubey BB, Nylund RE. Surface browning of carrots. Canadian journal of plant science. 1969 Jul 1;49(4):421-6. Dorrell DG, Chubey BB. Acceleration of enzymatic browning in carrot and parsnip roots by induced suberization. Amer Soc Hort Sci J. 1972. ). What is the main reason and how to prevent this problem?