Optimization of ultrasound and microwave-assisted extraction of sweet cherry tree branches and chemical component analysis by UPLC–MS/MS

Abstract

Sweet cherry tree branches have important food and medicinal value. The ultrasound and microwave-assisted extraction method is more efficient with higher yield than conventional extraction methods (heat-reflux, Soxhlet, etc.). Plant byproducts are known as sources of natural bioactive compounds. The objective of this study was to rationally use sweet cherry tree branches (SCTB) discarded during pruning. Ultrasonication and microwaves are considered green techniques, and an ultrasound and microwave-assisted extraction (UMAE) method was established to obtain extracts from SCTB by response surface methodology. A mathematical model was established using the Box–Behnken design, and the effects of various factors and their interactions were analyzed as well. Taking the yield (w/w) as the objective, the optimal process conditions for UMAE of SCTB were 56 mL·g−1 liquid–solid ratio, 34 min extraction time, and 40–50 mesh particle size. The yield of SCTB extracts was 5.02%, which was close to the theoretical prediction. The optimized extraction process can obtain a higher yield than that of conventional extraction methods. The chemical composition of the extracts was identified by HPLC–MS/MS, and 400 metabolites, including carboxylic acids and derivatives (29%), fatty acyls (19%), organooxygen compounds (15%), flavonoids (12%), benzene and substituted derivatives (12%), phenols (8%), and imidazopyrimidines (5%), were annotated and classified. L-arginine and mannitol were the main chemical components of the SCTB extracts, suggesting their potential uses in the food and medical industries.