Choice of time of harvest influences the polyphenol profile of globe artichoke

The quantity and composition of polyphenols in plant tissue were determined by a combination of genotype, growing environment and post-harvest processing procedures. To establish the influence of solar radiation and air temperature on the polyphenol content of globe artichoke, field-grown plants of the re-flowering cultivar 'Violetto di Sicilia' were successively harvested once a month over the period November through April. The polyphenol profile of the various parts of the plant was responsive to harvest time, both quantitatively and qualitatively. The combination of low air temperature and solar radiation level experienced during February in particular enhanced the total polyphenol content in the leaves, floral stem and bracts (reaching, respectively, 12.44, 18.10 and 15.38 g kg−1 dry matter). However, the polyphenol content of the receptacle was more strongly influenced by the level of solar radiation, and reached 9.46 g kg−1 dry matter during April. Qualitative differences were also documented with respect to the identity of the predominant individual polyphenol compounds present. The growing environment represented by the combination of air temperature and solar radiation was a major determinant of the polyphenol content of the globe artichoke plant.