Abstract
Edible flowers not only make colourful dishes more attractive, but also have the potential to impart unique flavours and enhance taste, and in recent years flowers have become increasingly popular as fresh vegetables around the world. To date, there have been some positive results on the functionality of edible flowers and their use as nutritional supplements, but few reports have investigated changes in their aroma due to cultivation conditions and processing of edible flowers. In this paper, we introduce a study on the effects of drying of edible flowers, different growing districts and harvesting times on the functional properties and aroma in rose petals.
When four edible rose cultivars were dried using different drying methods, the total polyphenolic content and antioxidant activity of ‘Mariah’ and ‘Yves Piaget’ were almost equal to those of fresh petals in moisture absorption and 55°C drying plots. The total polyphenolic content of both cultivars in the moisture absorption drying plots remained almost constant from immediately after drying to 60 days of storage. Total carotenoid content was highest in fresh flower petals of ‘New Birdie’ and decreased significantly in all drying treatments, further decreasing with storage days. The content of aroma compounds in fresh flower petals was higher in ‘Kana Rose’ and ‘Yves Piaget’, but significantly decreased in all four cultivars in all drying treatments. Therefore, it is clear that during drying of flower petals of the four cultivars tested in this study it is difficult to retain the fragrance, although moisture absorption drying is useful for retaining polyphenolics and carotenoids.
When edible rose ‘Yves Piaget’ was grown at different districts, differences in the aroma component content were observed between districts. The relationship between the differences in aroma component content at different growing districts and the temperature at the growing districts was investigated, and a strong negative correlation was found between the diurnal variation and total aroma component content. It was therefore inferred that a decrease in the diurnal variation leads to an increase in the aroma component content.
When edible roses ‘Dramatic Rain’ were harvested at different times of the year, the ‘Dramatic Rain’ aroma varied between rose-like and floral-like aromas, suggesting that the aroma impression varied depending on the harvest time. In this study, flowers harvested in October were judged to have the most floral and intense fragrance.
These results indicate that the aroma of edible roses varies depending on the processing and cultivation method. Therefore, it is necessary to select the harvesting time, production districts and processing methods according to the purpose of use.
