Salmon (Salmo salar) Side Streams as a Bioresource to Obtain Potential Antioxidant Peptides after Applying Pressurized Liquid Extraction (PLE)

Abstract

The pressurized liquid extraction (PLE) technique was used to obtain protein extracts with antioxidant capacity from salmon muscle remains, heads, viscera, skin, and tailfins. A protein recovery percentage ≈28% was obtained for all samples except for viscera, which was ≈92%. These values represented an increase of 1.5–4.8-fold compared to stirring extraction (control). Different SDS-PAGE profiles in control and PLE extracts revealed that extraction conditions affected the protein molecular weight distribution of the obtained extracts. Both TEAC (Trolox equivalent antioxidant capacity) and ORAC (oxygen radical antioxidant capacity) assays showed an outstanding antioxidant activity for viscera PLE extract. Through liquid chromatography coupled with electrospray ionization triple time-of-flight (nanoESI qQTOF) mass spectrometry, 137 and 67 peptides were identified in control and PLE extracts from salmon viscera, respectively None of these peptides was found among the antioxidant peptides inputted in the BIOPEP-UMP database. However, bioinformatics analysis showed several antioxidant small peptides encrypted in amino acid sequences of viscera extracts, especially GPP (glycine-proline-proline) and GAA (glycine-alanine-alanine) for PLE extracts. Further research on the relationship between antioxidant activity and specific peptides from salmon viscera PLE extracts is required. In addition, the salmon side streams studied presented non-toxic levels of As, Hg, Cd, and Pb, as well as the absence of mycotoxins or related metabolites. Overall, these results confirm the feasible use of farmed salmon processing side streams as alternative sources of protein and bioactive compounds for human consumption.

Steam Explosion-Assisted Extraction of Protein from Fish Backbones and Effect of Enzymatic Hydrolysis on the Extracts

“…Accordingly, glycine and hydrophobic amino acids (alanine, proline, hydroxyproline, valine, and leucine) are key factors for potential antioxidant activity, by improving the scavenging effect of hydrolysates on free radicals [35,39]. A recent study showed that several antioxidant small peptides, such as glycine-proline-proline (GPP) and glycine-alanine-alanine (GAA), are encrypted in the amino acid sequences of salmon viscera extracts [40]. Furthermore, acidic amino acids, such as glutamic acid and aspartic acid, can quench unpaired electrons and free radicals, by providing protons [41].…”

Role of Extracts Obtained from Rainbow Trout and Sole Side Streams by Accelerated Solvent Extraction and Pulsed Electric Fields on Modulating Bacterial and Anti-Inflammatory Activities

“…The determination of the ORAC values was carried out according to a previously described method [18,22]. A phosphate buffer (pH 7.0-7.4) was used as the blank group and 1 mM Trolox solution was the standard.…”

“…The TEAC assay was used to determine the ABTS free radical scavenging capacity of the extracts. According to De la Fuente's method and with some modifications, 25 mL ABTS (7 mM) and 440 µL K 2 S 2 O 8 (140 mM) were mixed to obtain an ABTS + working solution, which was stored at room temperature in the dark for about 12-16 h for use [18]. The ABTS + working solution was diluted with 96% (v/v) ethanol to maintain the absorbance of 0.700 ± 0.020 at 734 nm.…”

“…ASE is also a green and efficient extraction method which works in a high-pressure environment and can increase the extraction rate of the samples through the accumulation of heat and pressure. Due to its environmentally friendly and safe characteristics, ASE has been widely used in the extraction of a variety of high-added-value compounds [16,17] and has recently been shown to be a useful technique to recover bioactive peptides with antioxidant and antimicrobial properties from salmon side streams [18].…”

Conversion of Fishery Waste to Proteases by Streptomyces speibonae and Their Application in Antioxidant Preparation

“…Typically, these kinds of discards are landfilled, burned, dumped, or abandoned, resulting in a variety of environment, biodiversity, and detrimental health issues [1,2]. Many kinds of fishery wastes, such as fish head, viscera, and skin; squid pen; shrimp head and shell; and crab shell, are largely composed of protein, which could be reutilized for a wide array of purposes [1,3,4]. Of them, proteinaceous wastes from the fishery processes have been gaining great interest in recent years from numerous researchers, concerning the conversion of these materials to high-value products via microbes.…”