Extraction and Characterization of Antioxidant Peptides from Fruit Residues

Abstract

Fruit residues with high protein contents are generated during the processing of some fruits. These sustainable sources of proteins are usually discarded and, in all cases, underused. In addition to proteins, these residues can also be sources of peptides with protective effects against oxidative damage. The revalorization of these residues, as sources of antioxidant peptides, requires the development of suitable methodologies for their extraction and the application of analytical techniques for their characterization. The exploitation of these residues involves two main steps: the extraction and purification of proteins and their hydrolysis to release peptides. The extraction of proteins is mainly carried out under alkaline conditions and, in some cases, denaturing reagents are also employed to improve protein solubilization. Alternatively, more sustainable strategies based on the use of high-intensity focused ultrasounds, microwaves, pressurized liquids, electric fields, or discharges, as well as deep eutectic solvents, are being implemented for the extraction of proteins. The scarce selectivity of these extraction methods usually makes the subsequent purification of proteins necessary. The purification of proteins based on their precipitation or the use of ultrafiltration has been the usual procedure, but new strategies based on nanomaterials are also being explored. The release of potential antioxidant peptides from proteins is the next step. Microbial fermentation and, especially, digestion with enzymes such as Alcalase, thermolysin, or flavourzyme have been the most common. Released peptides are next characterized by the evaluation of their antioxidant properties and the application of proteomic tools to identify their sequences.

Expeller-Pressed Pomegranate Seed (Punica granatum L.) as a Protein Source for the Production of Antioxidant Peptides

“…Our results showed that the pattern of protein solubility of pomegranate seed proteins was U-shaped with an apparent dip in solubility around pH 4-5, especially at pH 4.4. These results are consistent with the reports of most research in which the isoelectric pH range for most plant proteins was considered to be at pH = 4-5(Gerzhova et al 2016;Olivares- Galván et al 2020). According to the results, the pomegranate seed protein concentrate contains high protein content (70.2 ± 0.36%).…”

Comparative study of factors affecting the recovery of proteins from malt rootlets using pressurized liquids and ultrasounds

“…Fifteen buffers covering from pH 5.5 to pH 13.0 were employed. This range was selected taking into account previous authors experience working with plant proteins ( Olivares-Galván et al, 2020 ; Ma et al, 2022 ). In some cases, different buffers with identical pH were used.…”

“…Extraction of proteins can be promoted by favouring physical contact between proteins and the extracting medium using techniques such as pressurized liquid extraction (PLE) or ultrasound-assisted extraction (UAE) ( Olivares-Galván et al, 2020 ). UAE is a well-known technique to make extractions faster and more efficient by providing mechanical energy through a phenomenon called cavitation .…”

“…UAE is a well-known technique to make extractions faster and more efficient by providing mechanical energy through a phenomenon called cavitation . UAE has been extensively applied for the extraction of proteins, including the works performed by the own group ( Olivares-Galván et al, 2020 ). Nevertheless, no work has explored the extraction and characterization of proteins from MR. PLE, on the other hand, allows solvents to achieve temperatures higher than their atmospheric boiling point without evaporation by the application of high pressures.…”

Introduction to the Special Issue: New Advances in the Research of Antioxidant Food Peptides

“…It begins with a group of papers describing the antioxidant potential of vegetal food-derived hydrolyzates and peptides. The review of Olivares-Galván et al [1] summarized the existing evidence on antioxidant peptides released from fruit residues, focusing on the current techniques used in their extraction, purification, fractionation, and identification, the strategies followed to allow the peptides' release from source protein, as well as the assays used to determine their antioxidant activity. Two research articles described the potential of two vegetal proteins as sources of antioxidant peptides.…”