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

Mário Bordalo,Margarida Serra,Ana Teresa Serra,Andreia Bento Silva,Hermínio C De Sousa,Maria R Bronze,Ana Paula Terrasso,Mara E M Braga,Catarina Brito,Inês J Seabra,Catarina M M Duarte

doi:10.3390/antiox10091469

Abstract

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% v/v) 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.

Highlights

Bravo de Esmolfe (BE) is a traditional Portuguese apple variety only produced in a restricted and small inland region called “Beiras” in the centre–northern Portugal
Adil and co-authors optimized the extraction conditions to improve the recovery of total phenolics from apple pomace skin and pulp residues of Starking and Amasya apple varieties that remain after pressing the fruits for juice production) by testing a range of CO2 + ethanol concentrations (14–20%), extraction times (10–40 min), pressures (20–60 MPa) and temperatures
The experiments were carried out with the residues of BE apple, which is a traditional Portuguese variety that presents high content of phenolic compounds, including catechin, epicatechin and quercetin glucosides [3]

Summary

Introduction

Bravo de Esmolfe (BE) is a traditional Portuguese apple variety only produced in a restricted and small inland region called “Beiras” in the centre–northern Portugal. This apple is classified as a “Protected Designation of Origin” product and it is very appreciated by consumers due to its peculiar flavour and aroma [1,2]. The main phenolic compounds identified in BE were catechin, epicatechin, chlorogenic acid, quercetin glucosides and procyanidins B1 and B2; its antioxidant activity (ORAC value) ranged from 1503 to 2089 μM TEAC/100 g fresh weight (fw) [5]. There is a need to develop strategies to efficiently extract bioactive (e.g., antioxidant) compounds from these agro-food residues with the aim to develop high-added value food ingredients from BE with health-promoting effects

Methods

Results

Conclusion