Variation in chilling susceptibility of Jicama roots

Jicama (Pachyrhizus erosus) is a traditional root vegetable of Mexico. Important quality characteristics include a smooth well shaped root, freedom from mechanical damage to the peel, and a crisp white flesh. No chilling injury is observed on roots stored 3 to 4 weeks at 13 degrees C. At lower storage/transit temperatures, chilling injury of jicama is manifested in various ways: after removing from 0 degrees C storage, texture is "rubbery" and roots decay rapidly; after 5 degrees C storage, external decay and internal graying of the pulp are common; and after 10 degrees C storage, external quality is typically not affected but severe internal discoloration can occur. All these symptoms of chilling injury are observed on jicama exported and distributed in the United States. A selection of cultivar Agua Dulce grown on the west coast of Mexico had a well developed peel, a starchy flesh, and required 3 weeks at 10 degrees C to show significant internal browning and 2 weeks at 5 degrees C to show chill-induced external decay. Another selection of the same cultivar grown in the Bajio area of central Mexico had a crisper more succulent flesh but after <1 week at 10 degrees C showed significant internal browning and changes in texture.