Using High-Pressure Technology to Develop Antioxidant-Rich Extracts from Bravo de Esmolfe Apple Residues

• Main Authors: Mário Bordalo (Author), Inês J. Seabra (Author), Andreia Bento Silva (Author), Ana Paula Terrasso (Author), Catarina Brito (Author), Margarida Serra (Author), Maria R. Bronze (Author), Catarina M. M. Duarte (Author), Mara E. M. Braga (Author), Hermínio C. de Sousa (Author), Ana Teresa Serra (Author)
• Format: Book
• Published: MDPI AG, 2021-09-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antiox10091469; 2076-3921
• Keywords: Bravo de Esmolfe; apple; antioxidants; CO₂ extraction; phenolic compounds; Caco-2 cells; Therapeutics. Pharmacology; RM1-950
• Source: Antioxidants, Vol 10, Iss 9, p 1469 (2021)

Bravo de Esmolfe (BE) is a traditional Portuguese apple highly appreciated by consumers due to its peculiar flavor and aroma. This apple contains higher concentration of phenolic compounds than other cultivars and is thus considered a rich source of antioxidants. Its sensorial and functional properties have attracted farmers' associations to increase BE production. However, a large quantity of apples is wasted due to storage/transportation procedures that impact BE's quality attributes. In this work, we applied high-pressure extraction methodologies to generate antioxidant-rich fractions from BE residues aiming at adding high value to these agro-food by-products. We performed a first extraction step using supercritical CO₂, followed by a second extraction step where different CO₂ + ethanol mixtures (10-100% <i>v</i>/<i>v</i>) were tested. All experiments were carried out at 25 MPa and 50 °C. Extracts were characterized in terms of global yield, phenolic content and antioxidant activity using chemical (ORAC, HOSC, HORAC) and cell-based assays (CAA). We demonstrated that, although the pressurized 100% ethanol condition promoted the highest recovery of phenolic compounds (509 ± 8 mg GAE/100 g BE residues), the extract obtained with 40% ethanol presented the highest CAA (1.50 ± 0.24 µmol QE/g dw) and ORAC (285 ± 16 µmol TEAC/g dw), as well as HOSC and HORAC values, which correlated with its content of epicatechin and procyanidin B2. Noteworthy, this fraction inhibited free radical production in human neurospheroids derived from NT2 cells, a robust 3D cell model for neuroprotective testing.