EFFECT OF THE NUTRIENT SOLUTION AND SHELF-LIFE CONDITIONS ON THE ESSENTIAL OIL PROFILE OF MINIMALLY PROCESSED DILL (ANETHUM GRAVEOLENS L.) GROWN IN A SOILLESS CULTURE SYSTEM

In recent years, the growing market demand in fresh-cut conveniences expanded its interest in minor leafy vegetables with quality properties such as taste and nutraceutical value. Dill is commonly used out of season as dried leaves or spicy seeds in North Europe, while it could be exploited as baby leaf convenience if cultivated in soilless systems, enlarging its availability on the market all year around. Investigations were conducted to study the effects of nitrogen level (4, 8; 16 mM) and NO₃^--N/NH₄⁺-N ratio (20:80; 40:60; 60:40) in the nutrient solution during plant growth, two films with different oxygen permeability levels (high permeability, HP, 1,990 cm³ m^-2 d^-1; low permeability, LP, 1,330 cm³ m^-2 d^-1) and storage temperatures (4, 12°C) during shelf-life on the essential oil profile of minimally processed dill with a 7-day shelf-life. Two experiments were performed in November 2006. Dill was grown in 60-cell styrofoam trays using a floating irrigation system in greenhouse. At harvest, dill was packaged in polypropylene flowpack in tray. Essential oil profile was analyzed at harvest and at the end of the shelf-life. Fresh weight loss was daily measured during shelf-life. At harvest, the essential oil profile was not significantly influenced by either N level or NO₃^--N/NH₄⁺-N ratio. After 7 days of shelf-life, fresh weight loss was greater at 12°C (1.5%) than at 4°C (0.5%); few compounds as limonene, anethole, carvone were not detected; myristicin decreased mainly using HP film (1^st exp. 37%; 2^nd exp. 55%). Furthermore, α-phellandrene and ß-phellandrene increased in the samples stored at 12°C (1^st exp.), and decreased in the samples packaged with HP film and stored at 4°C (2^nd exp.). Using the soilless culture system, dill was harvested at a younger stage than in commercial fields, limiting its effect on the essential oil profile, that reaches its optimal quality and concentration peak later in the growth stage. The essential oil profile was instead affected by the postharvest conditions.