Comparison of nutritional and sensory quality of processed and unprocessed wild rocket leaves during cold storage

Nutritional and sensory quality of wild rocket leaves ( Diplotaxis tenuifolia L., cv. Grazia) subjected to commercial processing and packaging were monitored for up to 7 days of cold storage and compared with the quality of unprocessed and unpackaged leaves from the same harvest. Nutritional quality was assessed by determining total phenolics, vitamin C and folate content. Sensory quality was assessed by quantitative descriptive analysis, combined with analysis of volatile organic compounds (VOCs). No change in vitamin C and folate content was observed in processed rocket leaves up to 7 days of cold storage, whereas unprocessed leaves showed a marked loss of both of them at the end of the storage time (52% and 71%, respectively). Total phenol content decreased during cold storage in both rocket leaves samples, but at a lower extent in the processed leaves. While most sensory attributes showed significant degradation during storage in both processed and unprocessed leaves, at the end of the storage time processed leaves had better retained some appearance (colour, turgidity, integrity), flavour (bitterness and bitter persistence) and texture (firmness and chewing consistency) attributes of the fresh leaves. A marked decrease during storage of some potent key odorants, such as ( Z )-3-hexenal, ( E )-3-hexenal, as well as 1-penten-3-one, corresponded to the weakening of fresh herbaceous/green sensory notes and pungency in both rocket leaves samples. Commercial processing and packaging operations proved to be effective at better preserving nutritional and sensory quality of wild rocket leaves and, thus, at prolonging their shelf life.