Effect of Elevated CO<inf>2</inf> during Low Temperature Storage on the Quality Attributes of Cut Spearmint

Abstract

The effect of elevated CO2 in a controlled atmospheric condition (CA) on the quality attributes of fresh-cut spearmint (Mentha spicata) during refrigerated storage is investigated in the present study. Cut stems of spearmint were exposed to the continuous flow of humidified air enriched with 0 (as a control), 5, 10 and 20% CO2 during storage at 5◦C. Weight loss, leaf colour, total phenols, antioxidant activity, aromatic profile, ascorbic acid, ethanol, ammonia and ethanol-acetaldehyde concentrations were measured before and after storage for 5, 10 and 14 days. Over time, CO2 treatments increased the weight loss, surface colour, L* (from white to black) and b* (from blue to yellow) values, but lowered a* (from green to red). When compared to fresh spearmint, the lowest CO2 concentration was able to maintain the overall colour variations. The 20% CO2 treatment showed significant declines in the total phenolic content, antioxidant potential and low appearance score after 10 days, thus its quality assessment was terminated. Vitamin C levels decreased with time in all the treatments, although the 10% and 20% CO2 treatments had the lowest levels. The toxicity of the cell structures detected by the ammonia content increased and was significantly higher in all CO2 treatments. Storage in the CA with the gas composition at 5% preserved the aromatic profiles similar to those stored in air. In conclusion, increased CO2 did not improve the storability of fresh cut spearmint held at low temperatures, and the 20% gas composition had a significant negative impact on the visual quality.