Valorization of pumpkin peel as a source of bioactive compounds: optimization of heat- and ultrasound-assisted extraction

• Autor(a) principal: Leichtweis, Maria Gabriela
• Data de Publicação: 2020
• Outros Autores: Molina, Adriana K., Petropoulos, Spyridon Α., Carocho, Márcio, Pires, Tânia C.S.P., Dias, Maria Inês, Calhelha, Ricardo C., Oliveira, Beatriz, Pereira, Carla, Barros, Lillian
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/21650
• topic: Cucurbita maxima Duchesne; Natural food preservatives; Process optimization; Phenolic compounds; Pumpkin peel; Bioactivity; RSM

The peels from three pumpkin genotypes cultivated in Greece were assessed for their phenolic content and bioactive properties to obtain extracts with a high preservative capacity. The optimization of the extraction was performed through response surface methodology (RSM) based on a Box-Behnken experimental design after applying two extraction techniques: heat-assisted (HAE) and ultrasound-assisted (UAE) extraction. The implemented independent variables were time, solvent concentration, and temperature/power (for HAE/UAE), while as dependent variables the dry residue (DR), reducing power (RP), and total phenolic content (TP) were considered. In general, HAE was the most effective technique for 'TL' (75 min; 30 degrees C; 24% ethanol) and 'Voutirato' (15 min; 30 degrees C; 10% ethanol), while UAE was more effective for 'Leuka Melitis' (5 min; 400 W; 0% ethanol). The extracts obtained in the global optimum conditions for each genotype peel were then assessed for their phenolic profile, by HPLC-DAD-ESI/MS, and bioactive potential. Seven phenolic compounds were detected, including four flavonoids, two phenolic acids, and one flavan-3-ol. The extracts presented high antioxidant, antibacterial, and antifungal potential, with no cytotoxicity for non-tumor cells. The optimized conditions for the extraction of preservative compounds from bioresidues were defined, allowing the acquisition of antioxidant and antimicrobial extracts and proving their potential for food application.