Functional proteins and peptides obtained from fish by-products

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Valorization of Fish by-products: purification of bioactive peptides from codfish blood and sardine cooking wastewaters by membrane processing

Publication . Ghalamara, Soudabeh; Silva, Sara; Brazinha, Carla; Pintado, Manuela

2020Journal article

Open access

Functional proteins and peptides obtained from fish by-products

Publication . Ghalamara, Soudabeh; Pintado, Maria Manuela Estevez; Silva, Sara Nunes da Costa e; Ferreira, Carla Maria Carvalho Gil Brazinha de Barros

Marine processing industries face significant challenges due to excessive by-products, which contribute to both environmental and economic issues. By-products from fish processing, which can constitute between 30% and 70% of the fish's total weight, exacerbate these challenges. Activities like washing, thawing, cooking, and fishmeal production generate more wastewater, intensifying the industry's environmental impact. This research explored using fish by-products like sardine cooking effluent and codfish bloodwater (CFBW) in a sustainable, zero-waste approach. The functional proteins and peptides extracted from fish by-products enhanced their value. The research evaluated their properties and potential food uses, aligning with circular bioeconomy principles. Fish by-products were fractionated using membrane technology at laboratory and pilot scales, aligning with zero-waste and biorefinery approaches. Ultrafiltration (UF) membranes were used to extract bioactive peptide-enriched fractions from sardine cooking effluent and CFBW at the laboratory scale. The process involved analyzing the selective permeation of small peptides (<1 kDa) using different membranes. The membranes effectively rejected (>10 kDa) of proteins and peptides but had relatively low rejection of <1 kDa peptides, with UP010 from CFBW achieving a 2% rejection rate and GH from sardine cooking effluent operating at minimum pressure (1 bar) achieving a 23% rejection rate. Peptides from CFBW using MW and UP010 membranes demonstrated potent antioxidant activity (high ABTS+ and ORAC values). However, the peptide fractions from sardine cooking effluent using the GH membrane did not enhance antioxidant activity. Nevertheless, the peptide fractions from CFBW (UP010 membrane) and sardine cooking effluent (GH membrane, 1 bar pressure) inhibited E. coli growth. Peptide-enriched fractions from CFBW were successfully obtained using a pilot-scale process involving microfiltration (MF), UF, and reverse osmosis (RO). The process aimed to fractionate CFBW into protein- and peptide-rich fractions. Chemical and biological characterization revealed that CFBW and pretreated CFBW consisted primarily of proteins and peptides. UF membrane fractions had lower protein content but higher ash levels. The UF retentate with a MWCO of 50 kDa, followed by RO, displayed the highest antioxidant values, indicating the presence of potent antioxidants. Additionally, the UF permeate obtained with a MWCO of 50 kDa from the MF-PFG showed antimicrobial activity against E. coli. A pilot-scale integrated membrane process was developed to obtain protein- and peptiderich fractions from sardine cooking effluent. The process used UF, nanofiltration (NF), and RO combined with enzymatic hydrolysis. Specifically, the RO retentate fractions of NF retentate were derived from diluted sardine cooking effluent, diluted hydrolyzed UF retentate, and diluted non-hydrolyzed UF retentate. The process involved UF, nanofiltration (NF), and RO combined with enzymatic hydrolysis. Specifically, the RO retentate fractions of NF retentate fractions were derived from water-diluted sardine cooking effluent (sardine cooking effluent-NF-RO), water-diluted UF retentate hydrolyzed (UF-H-NF-RO), and water-diluted UF retentate non-hydrolyzed (UF-NH-NF-RO). UF-H-NF-RO showed enhanced antioxidant and antimicrobial activities. The UF-NH-NF-RO peptide fraction displayed significantly enhanced functional properties in terms of WHC, FBC, emulsifying properties, and foaming properties at pH 4. In vitro digestion analysis showed this fraction also had the highest antioxidant activity, and none of the fractions exhibited cytotoxicity. Finally, foamy fish sauces (FFSs) were developed and evaluated using protein/peptide and lipofish fractions obtained from centrifugation of sardine cooking effluent. The control sample (CS) used a butter-based sauce emulsified with lecithin. An alternative lipofish sauce (LS) substituted unsalted butter with fish oil and included lecithin as the emulsifier. Three other formulas, namely lipofish-sardine cooking effluent-NF-RO-sauce (LSS), lipofish-UFH-NF-RO-sauce (LHS), and lipofish-UF-NH-NF-RO-sauce (LNHS), replaced unsalted butter with fish oil and incorporated a combination of protein/peptide fractions and lecithin. Despite minor physicochemical differences, the sauce formulas showed improvements compared to the control, including enhanced fatty acid (FA) content and profile, slightly reduced viscosity, improved foaming capacity, and enhanced foam stability. In vitro digestion analysis demonstrated high recovery of FAs, with the formula LNHS exhibiting the highest efficacy in scavenging ABTS radicals, indicating strong antioxidant properties. Furthermore, the FFS received remarkable acceptance from the trained panelists, who highly praised its texture, aroma, color, and flavor. This study's findings on fish by-products have significant implications for sustainable development in the fish processing industry. The research showcased the potential to obtain functional ingredients through eco-friendly strategies, preserving their bioactivity. These outcomes promote responsible and sustainable fish processing, reducing waste and maximizing by-product utilization.

2025-03-07Doctoral thesis

Embargoed access

Funding agency

Fundação para a Ciência e a Tecnologia

Funding Award Number

SFRH/BD/149347/2019