Harvest Time Influences Inulin and Phenolic Accumulation of Globe Artichoke (Cynara cardunculus L.)

The influence of harvest time on globe artichoke (Cynara cardunculus L.) inulin and phenolics was investigated to inform selection of superior lines with improved nutritional quality. Lines of unknown genetics were harvested early, middle or late in the growing season. Inflorescence size and edible portion (EP) yield, fructan content, including inulin-type fructans, inulin profile, phenolic concentrations, color change (browning) after cutting and polyphenol oxidase activity were measured. Early harvested artichokes developed larger inflorescences (average 248.3 g) compared to late harvested artichokes (average 178.5 g) and had higher mean total phenolic concentrations (TPC) (8.67 g kg^-1) in the EP. Late harvest artichokes had higher mean fructan concentrations (61.56 g kg^-1 fresh weight) and higher mean yield of EP (54.9%) compared to early harvest artichokes (36.1%). Inulin concentration was positively correlated with mean daily solar radiation exposure, while phenolic concentration was negatively correlated. The CIE b* value (yellowness) of the artichoke receptacle immediately after cutting was significantly, positively correlated with the TPC, chlorogenic acid, and dicaffeoylquinic acid isomer (DiCQA) concentrations. The rate and intensity of polyphenol oxidase-mediated browning after cutting was correlated with phenolic concentrations, with DiCQA having the strongest association. This research demonstrates the potential benefits of evaluating a wide range of variables to select superior artichoke lines with improved nutritional quality.