Inulin and sugar contents in Helianthus tuberosus and Cichorium intybus tubers:: Effect of postharvest storage temperature

Inulin, sucrose, fructose, and glucose contents in tubers of Helianthus tuberosus (Jerusalem artichoke) and Cichorium intybus stored at different temperatures (-18, 4, and 18 degreesC) after harvesting were followed. Inulin content in both tubers decreased during storage. In C. intybus this decrease was associated with increases in glucose and fructose contents. In H. tuberosus the fructan fraction having molecular weight between 800 and 1200 increased after sucrose reached its maximum content [1.3(.)10(-1) g (g d.w.)(-1)] in tubers stored at 4 degreesC. Fructose-to-glucose ratio was followed in H. tuberosus tubers harvested at different times; samples from plants subjected to different fertilization treatments were used. This parameter can be used for choosing the harvest date since it is related to the disappearance of the fructan fraction having molecular weight higher than 1200.