Prunus persica by-products: A source of minerals, phenols and volatile compounds

Large amounts of peach (Prunus persica) leaves and stems are by-products deriving from peach tree cultivation and canned industries. This work aimed to evaluate mineral nutrients, phenolic and volatile profile and anti- oxidant activities from the by-products of five peach cultivars (Early Maycrest, Sweet Cap, O’Henry, Flordastar and Rubirich). Minerals showed significant variations with respect to peach by-product. N showed higher contents in peach leaves among macronutrients, while Mn showed higher contents among micronutrients. Stems had high levels of Ca and traces of micronutrient levels. The HPLC-DAD phenols analysis showed twelve compounds identified (neochlorogenic and chlorogenic acids, catechin and epicatechin, gallic, caffeic, syringic, ferulic and coumaric acids, quercetin-3-rutinoside, quercetin-3-galactoside, cyanidin-3-glucoside, cyanidin-3-galactoside). Flavonols showed the highest values (quercetin-3-galactoside with 70.79–232.16 mg 100g-1 DW, quercetin-3-rutinoside with 63.88–206.37 mg 100g-1 DW), while the least content was observed for anthocyanins. Cultivar had a sig- nificantly (P < 0.05) impact on phenolic compounds. Comparing by-products, stems showed higher levels of phenols. The GC-MS volatile compounds analysis revealed 43 compounds in different percentages and occur- rences, depending on the cultivar and the by-product. Benzaldehyde was detected as the major volatile leaf component (70–95%), whereas myrcene (18–21%) and terpinolene (18–26%) were found to be the most im- portant compounds in stems. Methanolic extracts of mature leaves were characterized by lower antioxidant capacity. Finally, peach by-products could represent a natural source of minerals, volatiles and phenolic com- pounds with high antioxidant activities having a great potential use in food products as natural flavouring agents and as nutraceutical supplements and pharmaceutical and cosmetic molecules.