Recovery of healthy compounds in waste bracts of globe artichoke heads

Globe artichoke is a typical crop of Mediterranean Basin widely cultivated all over the world for its immature inflorescences, harvested in the early stages of their development. The nutritional and pharmaceutical properties of artichoke heads are linked to their chemical composition, which includes polyphenolic compounds (mainly chlorogenic acid), inulin and minerals. Moreover, the edible part is represented by about 45-50% of the total weight of the head and outer bracts represent a disposal that could be valorised for the recovery of healthy compounds. In this view the outer bracts of two genotypes (Romanesco C3 and Violetto of Provence) mainly cropped in Italy have been chemically characterized. The trial was conducted in 2019. Heads, cropped under organic practices, were provided by a local farmer of Eastern Sicily. A representative number of heads were weighed and outer bracts removed and lyophilized for the analyses. The contents in total protein (kjeldal method x 6.25), crude fiber (Weende method), inulin (HPAEC PAD ICS 3000), total minerals (muffle, 550°C), chlorogenic acid (5-O-caffeoylquinic acid), 1,5 dicaffeylquinic acid and apigenin (4,5,7-trihydroxyflavone acid) by HPLC DAD were determined. On the average of the two genotypes, inulin resulted 139 g kg-1 dm, crude protein 150 g kg-1 dm, crude fibre 314 g kg-1 dm, total minerals 80 g kg-1 dm. Total antioxidant compound as sum of the three investigated molecules resulted 568 mg kg-1 dm. The use of the residual bracts arising from the processing industry, like by-products, is desirable for recovery of biocompounds to be used in food industry for biofortification and development of new products with nutraceutical effect on intestinal microbiota or for animal feeding.