Hawthorn (Crataegus monogyna Jacq.) and whitebeam (Sorbus aria (L.) Crantz) are wild species traditionally used as ethnic foods in the Mediterranean area. Their red berries, and mainly the peels, may be used as ingredients due to their color (replacing other synthetic colorants) or functional properties. Some previous studies analyze all edible fruits, but there is very little literature on the composition and properties of the pulpless epidermis of the fruits of C. monogyna and no literature concerning the fruits of S. aria. Total phenolic compounds (TPC) and families of hydroxybenzoic acids, hydroxycinnamic acids, flavonols, and total monomeric anthocyanins were determined in the epidermis of C. monogyna and S. aria fruits. The in vitro antioxidant capacity was also determined using QUENCHER (Quick-Easy-New-CHEap-Reproducible) methodology. Anthocyanins profiles were analyzed in hydroalcoholic extracts through HPLC/MS. C. monogyna fruits presented higher content of TPC than S. aria, with hydroxybenzoic acids (2870.6 mg GAE/100g dw) as the major family, followed by flavonols (771.4 mg QE/100 g dw) and hydroxycinnamic acids (610.3 FAE/100 g dw). Anthocyanins were found in 251.7 mg cyanidin-3-glucoside/100 g dw, characterized by the content of cyanidin-O-hexoxide and peonidin-O-hexoxide. The levels of these compounds correlated with higher values of a* parameter (higher intensity of reddish color). These fruits also showed higher antioxidant capacity by Q-Folin-Ciocalteu and Q-FRAP. S. aria peels had fewer phenolic compounds, particularly anthocyanins (33.7 mg cyanidin-3-glucoside/100 g dw), containing different cyanidin derivatives. From these results, new insights about the composition of the epidermis of these wild fruits are provided, and their potential as ingredients for the food industry is corroborated.
Keywords: anthocyanins; antioxidant capacity; cyanidin-O-hexoxide; epidermis; flavonols; hydroxybenzoic acids; hydroxycinnamic acids; peel.