Effect of Blanching and Boiling on the Secondary Metabolism of Cultivated Cardoon Stalks: A Case Study of the Tuscany Region (Italy)

Cardoon (C. cardunculus var. altilis DC) is commonly cultivated in the Mediterranean area to produce stalks that are consumed once cooked. Before cooking, stalks are usually subjected to blanching, which means they are exposed to darkness for a few weeks. The present work analyzed the effect of field blanching carried out for 40 days in different ways (burying the stalks under soil or covering them with plastic sheet) on the total phenolic content (TPC), phenolic profile, cynaropicrin content (a bitter compound), and antioxidant activity (AA) of two cardoon cultivars. The nutraceutical quality of blanched cardoons was also investigated following boiling. The phenolic profile revealed a higher number of compounds in blanched stalks than in raw ones. The cynaropicrin content decreased in both cultivars after blanching, indicating a sensitivity to dark conditions and the effectiveness of blanching method in reducing its bitterness. The data presented contribute to improving the knowledge about the effect of blanching and boiling on the quality of cardoon stalks.