Trace elements in edible flowers from Liguria: an exploratory study.

Recently, the use of edible flowers has become very popular, both in traditional and innovative recipes, and now several floral species can be found not only in the kitchens of famous restaurants but also as packed salads in the supermarkets. The increasing consumer appreciation is due to the sensory properties of several flowers (taste, flavor, shape, color, texture) and to their nutritional value1, being low in fat and rich in nutrients. While several studies in literature have reported interesting antioxidant, antiinflammatory and anti-microbial activities for a number of species2, data on mineral composition are scarce3. The measure of the concentration of trace elements in edible flowers is important since some elements (e.g. As, Cd, Pb) are toxic even at low concentrations, and some other elements (e.g. Cu, Fe, Mn, Ni, Zn) are essential but they can be toxic or may induce allergic reactions when beyond certain levels. Moreover, there are hundreds of plant species which are known to be hyperaccumulators of metals and metalloids, but data are referred to aboveground biomass and never specifically to floral parts4,5. The present study is part of the INTERREG-ALCOLTRA project "ANTEA" (http://www.interregantea.eu/), aimed to increase the supply chain of edible flowers cultivated in Liguria (Italy) and PACA (France), mainly belonging to Asteraceae and Lamiaceae. The determination of the mineral composition and the highlighting of hyperaccumulator species, if any, was included in the toxicity checks. Petals of edible flowers (n=19) grown in West Liguria in controlled conditions in open grounds were freeze dried, grinded and analyzed. The concentrations of 10 trace elements (Cd, Co, Cu, Fe, Mn, Ni, Pb, Sr, V, Zn) were measured using atomic emission spectrometry with inductively coupled plasma source (ICP-OES). One sample, Acmella oleracea (L.) R.K. Jansen, Asteraceae, was considered as an outlier, showing Mn concentrations 15-fold higher than the mean value of the other samples. Regarding the remaining samples, PCA (Principal Component Analysis) allowed to separate the two families on the basis of the concentrations of Cd, Fe, Mn, V, resulting significantly higher in flowers of Asteraceae. Anyway, none of the studied samples showed health risk for consumers. Research is in progress on a larger set of samples in order to determine the mineral composition of the increasing number of edible floral species in use.