The Antioxidant Properties of Red Sour Cherry (Prunus cerasus L.) Extracts: Laboratory Assessment of Antioxidant Activity and Antioxidant Compounds under Temperature Variations

To understand the antioxidant activities of extracts of red sour (P. cerasus L.) cherries, known to have substantial antioxidant properties, L-ascorbic acid, phenols, flavonoids, and anthocyanins were measured under a variety of extraction conditions (mild heating and intermittent microwave exposure) for: i) whole juice extracts (WJE), ii) methanol-extracted juice (MEJ), iii) ddH2O-extracted pomace (dPOM), and iv) methanol-extracted pomace (mPOM). The antioxidant activity for WJE was changing with mild and prolonged exposure to heating or microwave, following a positive correlation (heating, 5 – 20 min.; microwave, 1 – 2 min.), and significantly variable with MEJ, dPOM, and mPOM. L-Ascorbic acid content was not affected with mild to prolonged heating or microwave exposure (WEJ and mPOM), except a mild increase with MEJ and dPOM. Similarly, total phenols assessed showed no significant variations, except mild increase (WEJ and mPOM), decrease (dPOM), and no significant change (MEJ). Total flavonoids content was increased under those conditions for WEJ, decreased for MEJ, and not affected for dPOM and mPOM. In contrast, anthocyanins showed differential variations with exposure (increase [WJE, MEJ, and mPOM], and decrease [dPOM]). Assessment of extraction means as compared with WJE revealed an increase in the antioxidant activity for MEJ, a decrease for dPOM and mPOM, significant increase in L-ascorbic acid, total phenols, and flavonoids contents for MEJ, dPOM and mPOM, and mild decrease in anthocyanin contents for MEJ, dPOM, and mPOM. These results confirm that red P. cerasus extracts contain a variety of antioxidants and that those antioxidants are sensitive to temperature variations.