Primary Screening of Antioxidant Activity, Total Polyphenol Content, Carotenoid Content, and Nutritional Composition of 13 Edible Flowers from Japan

Thirteen edible flowers, which are used as food ingredients in Japan, were evaluated as possible sources of antioxidants and biological compounds. The nutritional composition, total polyphenol content (TPC), carotenoid content, and antioxidant activity of the edible flowers were determined based on the oxygen radical absorbance capacity (ORAC). Water was the main constituent of edible flowers, and carbohydrates were the primary macronutrients. The TPC of the edible flowers varied from 1.47 to 13.08 mg gallic acid equivalent/g fresh weight (FW). Carotenoids, including β-carotene and β-cryptoxanthin, were detected mainly in the edible flowers with petal colors ranging from yellow to orange, but especially in primula and cosmos yellow flowers, which have yellow petals. The ORAC value of the hydrophilic extract (HORAC) of edible flowers was higher than the ORAC value of the lipophilic extract (LORAC). The total antioxidant capacity (TAC) ranged from 33.03 to 320.36 μM Trolox equivalent/g FW. The highest TPC and TAC were observed in cosmos yellow flowers. On the basis of Pearson’s correlation coefficient, the HORAC value and the TPC of the analyzed edible flowers were highly correlated (r=0.736). This preliminary study indicates that edible flowers are a potential source of antioxidants, and the addition of edible flowers to the human diet may be associated with health benefits.