The effect of modified atmosphere storage on the quality of fresh dill(Anethum graveolens L.)

Abstract

Because of its high perishability, fresh dill (Anethum graveolens L.) cannot be stored for more than a few days, even at low temperature. The present study was therefore undertaken to determine whether modified atmospheres based on changes in CO2 and O2 concentrations would benefit dill storage. Dill cv. Ducat was cultivated between October 2009 and January 2010. Plants were harvested at the fresh market stage (before flowering) and randomly selected leaves were weighed, placed in airtight plastic bags and stored for 10 days at 5°C. The atmospheres within the containers (O2-CO2-N2) were initially as follows: (1) 20-0-80 (air), (2) 20-10-70, (3) 10-0-90, and (4): 10-10-80. The changes in O2-CO2 concentrations were monitored during storage; fresh weight, chlorophyll, vitamin C and total phenolics concentrations were measured before and after storage. The oxygen concentration within the bags during storage fell to 12.5% (treatment 1) and 17.9% (treatment 2) indicating a reduction of respiration due to the inclusion of 10% CO2 within the initial atmosphere (20% O2). At an initial concentration of 10% O2, the oxygen level decreased to 5.5% and 5.8% in the absence or presence of 10% CO2 (treatments 3 and 4), respectively. In each case, the decrease in O2 was accompanied by a corresponding increase in CO2 concentration. Weight loss during storage ranged from 2.6-5.3% and the total phenolics levels decreased in all treatments except treatment 3 (10-0-90). Vitamin C and chlorophyll concentrations decreased during storage. Vitamin C loss was similar in all treatments, but chlorophyll loss was significantly higher in the treatments with 10% CO2. In consequence, although modified atmospheres containing 10% CO2 reduce respiratory activity they are of questionable value for dill because the decrease in chlorophyll concentration causes a decrease in quality.