The Collaborative International Dictionary of English v.0.48:

Pectose \Pec"tose`\ (p[e^]k"t[=o]s`), n. [Pectic + cellulose.]
   (Chem.)
   An amorphous carbohydrate found in the vegetable kingdom,
   esp. in unripe fruits. It is associated with cellulose, and
   is converted into substances of the pectin group.
   [1913 Webster]