Cherry (Prunus avium) phenolic compounds for antioxidant preservation at food interfaces

Cherry phenolics extracted by 90°C-water were loaded in a low-methoxyl-pectin (LMP) film for antioxidant preservation. Dark red films (pH = 3.46) contained flavonols (dihydrokaempferol-glucoside, quercetin-3-O-rutinoside), hydroxycinnamic acids (neochlorogenic, chlorogenic, 3-p-coumaroylquinic acids), and anthocyanins (cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside), with a 6.97 × 10−12 m2/s diffusion coefficient. Phenolics' stability was studied at constant relative humidity (RH: 57.7; 75.2%) and 25.0 °C. The pseudo-first-order de gradation rate was the highest (t1/2 = 3-2 months) and increased with the equilibration RH in darkness for anthocyanins, with simultaneous red vanishing by water nucleophilic attack. Instead, flavonols remained stable (t1/2 >1.5 years). Light (75.2%RH) induced the highest phenolics-degradation-rates, especially for anthocyanins (t1/2 = 11d), sensitizer, and film red color. Flavonols-decay was the slowest (t1/2 = 7-12 months). Antioxidant capacity paralleled phenolics-content. Hydroxycinnamic acids followed by flavonols could scavenge the singlet oxygen. Light-triggered LMP-matrix―phenolic interactions were determined, producing the lowest film water content and deformability. Cherry phenolics stabilized as a colored film constituted a food preserving antioxidant barrier.