CO2 modified atmosphere packaging: stress condition or treatment to preserve fruit and vegetable quality?

Abstract

In addition to the adoption of proper temperature and relative humidity, the selection of an atmosphere surrounding packaged fresh produce with reduced O₂ and/or increased CO₂ is one of the most widely used and useful tools to prolong the shelf-life of horticultural crops. However, as  O₂ and/or CO₂ values that might cause injury are strictly related to the commodity, they should be optimized for each product. Here three study cases are reported about the application of modified atmospheres (MA), with different CO₂ concentrations (0-40 kPa), to table grapes (cv. Italia) and sweet cherries (cv. Ferrovia) and, as short-term treatment (48 h at 0 °C), to fresh-cut artichokes (cv. Violet de Provence). In each trial, the effect of high CO₂ treatment on quality parameters was observed during cold storage. Concerning table grape “Italia”, our results show that low CO₂ (up to 10kPa) MA preserved the quality and sensory parameters of the fruit, whereas high CO₂ (> 20 kPa) caused a fermentative metabolism. As for sweet cherries 'Ferrovia', 20 kPa CO₂ MA helped to maintain the quality traits during storage. On the other hand, this fruit proved to be sensitive to CO₂ accumulation (over 20kPa) in hypoxic conditions, since it caused an increase in respiration rate and the biosynthesis of volatile fermentative metabolites. Finally, for fresh-cut artichokes, a short-term CO₂ treatment, up to 10kPa, reduced respiration rate and browning index, preserving the volatile profile, while high CO₂ (40 kPa) may have caused fermentative metabolism. In conclusion, the application of a MA enriched in CO₂ has been shown to have different effects on the quality parameters of the three products, in agreement with the fact that CO₂ sensibility depends on each specific fruit or vegetable under study.