Modifications to solubilized cell wall polyuronides of sweet persimmon (Diospyros kaki L. `Fuyu') were examined during development of chilling injury (CI) during storage and in response to heat treatments that alleviated CI. Storage at 0 °C caused the solubilization of a polyuronide fraction that possessed a higher average molecular mass than polyuronide solubilized during normal ripening. The viscosity of this fraction was 30-times that of normally ripened fruit. Fruit heat-treated before or following storage contained a soluble polyuronide fraction with a markedly lower average molecular mass and decreased viscosity than in chilling injured fruit. Heat treatment also impeded an increase in viscosity of the cell wall material if applied before storage. CI (gelling) was related to the release of polyuronide from the cell wall during storage and its lack of subsequent degradation. Heat treatments retarded polyuronide release but promoted degradation of solubilized polyuronides.