Response of Major Wild Leafy Vegetables to Controlled Atmosphere Storage

The effects of controlled atmosphere (CA) on quality maintenance and storage potential were estimated in four major, wild, leafy vegetables, specifically focusing on the incidence of CA-related disorders. After harvest, vegetables were precooled to 4-5 degrees C with a pilot-scale pressure pre-cooler. As a control treatment, perforated modified atmosphere packaging (MAP) was performed using 20 x 25 cm (W x L) polypropylene film bags with 8 punch holes. For CA treatments, two regimens were applied as 1% O-2 combined with 5% or 10% CO2 atmospheric compositions. Discoloration was evaluated during storage and on the shelf. The resulting storage potential was determined by overall marketability. The vegetables used in this study could be sorted into two groups based on their sensitivity to CA or MA-related disorders. Aster scaber (edible aster) and Cirsium setidens (Korean thistle) were sensitive to carbon dioxide and/or low oxygen injuries. As a typical symptom of physiological disorder, blackening discoloration increased under high carbon dioxide conditions over 5%. Storage potential of vegetables at 0 degrees C in the MAP condition was approximately 3 weeks for edible aster and 4 weeks for Korean thistle leaves. Allium ochotense (myeongyi) and Heracleum moellendorffii (East Asian hogweed) did not show low oxygen and high carbon dioxide injuries even under the 1% O-2 + 10% CO2 regimen. Storability of these two commodities was longer than 4 weeks under both MAP and CA conditions. In myeongyi leaves, CA effects were clearly observed under 1% O-2 + 5-10% CO2 conditions while in East Asian hogweed leaves, the beneficial effects were similar to those in MAP storage.