Effects of different storage conditions on the colour, antioxidant activity, and volatile components of edible roses

Abstract

This study examined the changes in petal colour, antioxidant activity, and volatile components of miniature roses, one of the most popular edible flowers in Japan, when stored under different conditions. In total, six storage treatments were examined: 5°C and 75% relative humidity (RH) for 3 d (75%-3D plot); 5°C and 75% RH for 6 d (75%-6D plot); 5°C and 96% RH for 3 d (96%-3D plot); 5°C and 96% RH for 6 d (96%-6D plot); -25°C for 3 d (F-3D plot); and -25°C for 6 d (F-6D plot). As a control, a measurement was conducted on day 0 without storage (0D plot). There were no significant differences in flower width, fresh weight, and total polyphenol concentrations among the storage treatments. DPPH radical scavenging activity decreased during storage, especially during freezing storage, but was higher in the 75%-3D plot than that in the other storage conditions. A colour difference was found between the cold and freezing storage treatments because of colour changes after freezing and thawing. The sweet aroma decreased during storage, and a bad smell was detected in the freezing treatment. Freezing storage was thus unsuitable for storing edible roses because it degraded colour, decreased antioxidant concentrations, and increased a bad smell. The flower colour measured using a chromameter and DPPH radical scavenging activity in the 75%-3D plot were not significantly different from those in the 0D plot. Further, the total volatile component contents in all 6D plots were lower than those in all the 3D plots during cold storage. Therefore, these findings indicate that edible roses should be stored under refrigeration at 75% RH and used within approximately three days after purchase. This information can be helpful to food, cosmetic, and pharmaceutical industries that require preservation of edible flowers.