Influence of high CO2 atmosphere composition on fresh-cut artichoke quality attributes

Atmosphere modification can improve the storability of some fruits and vegetables, but also has the potential to induce undesirable effects. In this work, the effect of high-CO2 atmospheres on the quality of fresh-cut artichokes (Cynara cardunculus L. subsp. scolymus (L.) Hayek 'Catanese') was tested. Freshly harvested artichoke heads were cut into halves and stored at 5°C in air (control) and in air with 5, 15, and 25% CO2. Initially, and after 2, 4, and 8 days of storage, quality attributes were monitored, including colour, overall appearance, and weight loss. In addition, chemical determinations, such as ammonia accumulation in artichoke tissues and polyphenol oxidase (PPO) activity were carried out. Samples stored in air+25% CO2 showed a tendency to develop brown spots on the external bracts, as a probable sign of intolerance to high CO2 concentration. As consequence, the a* value was significantly higher, while b* value and hue angle were significantly lower than the other treatments; the overall appearance also was lower, reaching below the limit of marketability at the end of the experiment. On bract cut surfaces L* value showed a slightly higher retention for the sample stored in 5% CO2 than for the other treatments. The storage in presence of CO2 controlled weight loss of the cut artichokes, with samples stored in air +5% and in air+15% CO2 showing the lowest values. At the end of the storage, ammonia accumulation was higher for sample stored in air+25% CO2. No substantial differences in PPO activity were found among different treatments. The presence of high CO2 concentrations in the storage atmosphere have been proven to be deleterious for fresh-cut artichokes, while only slight beneficial effects were observed for the lowest concentrations. For this reason, the avoidance of extreme conditions in terms of CO2 concentrations within the packages should be the main objective when designing a modified atmosphere packaging (MAP) system for freshcut artichokes.