postharvest.ucdavis.edu/Commodity_R...les_English/
Maturity Indices
Jicama (Pachyrhizus erosus) is a warm season legume root crop. It is also called Yam Bean and is a brown skinned turnip-shaped root eaten raw or cooked. Jicama roots can be harvested at various stages of development. Young tender roots (100-150 g) harvested from green plants are found in specialty markets. Fully mature roots, however, weigh from 250-1500 g. Mature roots are characterized by their size and well-developed periderm as well as their starchy-sweet flavor. To favor hardening of the periderm, plant tops are removed mechanically or irrigation is stopped.
Quality Indices
Good quality jicama roots should be smooth and firm, with uniform shape and size, be free from mechanical damage to the skin, and have a crisp, succulent, white sweet-starchy flesh. There are no U.S. Grades for jicama. In Hawaii, however, two grades are recognized based on size and freedom from defects (dirt, discoloration, growth cracks, roughness, insect damage, mechanical injury).