High CO2 effects on postharvest biochemical and textural properties of white asparagus (Asparagus officinalis L.) spears

The effects of high CO2 concentration (10% CO2, 17% O2) on the changes of functional cell wall components (pectic substances, hemicellulose, cellulose, lignin), mechanical properties, content of free soluble sugars (sucrose, glucose, fructose), and respiration activity were studied in harvested white asparagus spears stored at 10 and 20 °C, respectively, for up to 7 d. Spears stored at 2, 10 and 20 °C in air were studied as controls, where the 2 °C condition indicated the effects of cold storage. During storage, respiration activity declined only slightly, irrespective of the CO2 and temperature regime. Spears stored at 20 °C under both CA and normal air became less stiff and more elastic, however, tissue toughness increased significantly. Changes in toughness were associated primarily with the dynamics of lignin and cellulose, revealing a strong correlation (r2 = 0.81). High CO2 concentration inhibited the synthesis of cellulose and, to some extent, lignin accumulation at 20 °C. Additionally, elevated CO2 inhibited the degradation of soluble carbohydrates. In contrast, slightly lower temperatures of 10 °C in combination with high CO2 did not have a pronounced effect on changes in structural carbohydrates (lignin, cellulose, hemicellulose and pectins). The effect low temperature (2 °C) under normal atmosphere conditions resulted in the inhibition of cell wall changes in asparagus spears.

► High CO2 storage reduced asparagus spear toughening only at room temperature (20 °C). ► Changes in toughness were associated primarily with dynamics of lignin and cellulose. ► Primary cell walls compounds (pectin, protein) were less affected by high CO2. ► Only at 20 °C, high CO2 inhibited respiration activity and consumption of soluble solids. ► Inhibitory effects of high CO2 were similar to those at low temperature storage (2 °C).