Strawberry Fruit Softening: The Potential Roles of Polyuronides and Hemicelluloses

Polyuronides and hemicelluloses derived from ethanol powders or cell walls of strawberry ( Fragaria × ananassa , Duch. Dover) receptacle tissue were examined to determine if these wall polymers might be involved in the softening of this fruit. Throughout maturation and ripening, total polyuronides increased on a per fruit basis although as a percentage of ethanol powder they remained constant. Gel‐filtration chromatography confirmed that polyuronide solubility was not correlated with extensive enzymic hydrolysis, an observation consistent with the fact that D‐galacturonanase (polygalacturonase) activity was not detected in strawberry fruit. The sugar composition of alkali‐soluble wall polymers showed little change throughout development. However, changes occurred in the molecular weights of these polymers during ripening.