Effects of short-term low temperature storage on mechanical and chemical properties of white Asparagus cell walls

White asparagus spears, wich are very perishable horticultural products, are normally stored at low, non-freezing temperatures to prevent quality losses for few days. On the other hand, low non-freezing temperatures may induce cold-acclimation responses in many perennial plants. This may affect the mechanical and chemical attributes of the products' texture. For fresh asparagus spearstexture is the predominant but also very complex quality indicator. To address this complexity in detail, the dynamics and interactions between mechanical texture characteristics, water status, and physical and chemical cell wall properties were investigated in white asparagus spears during short-time storage at different storage temperatures. Tissue stiffness as indicated by both the apparent quasi-static elastic modulus E and the dynamic acoustic stiffness S, declined at storage temperature of 0°C and 20°C, whereas they remained nearly constant at 5°C and 10°C. Changes in pressure potential closely reflected the variation in tissue stiffness. These changes in elastic properties paralleled an increase in water insoluble pectic substances. In contrast, tissue strength of asparagus spears, wich was determined as the mean radial cutting force, declined at all storage temperatures after two days of storage. This decline, wich was more pronouced at 0°C and 5°C, correlated with the decrease in the EDTA soluble pectin fraction and with the increaseing water potential. This increase in water potential occured without changes in water content but resulted from the rapid decline in the osmotic content partially due to a reduction in glukose content. In contrast, the storage treatment did not affectfructose and sucrose concentration but significantly induced myo-inositol accumulation especially in spears stored at low temperatures. In contrast to asparagus roots no indications of cold acclimation or drought stress response occured in stored spears. Hence, the variation in tissue texture seems to result from developmentally regulated chances in cell wall properties.