A Review on Fish Skin-Derived Gelatin: Elucidating the Gelatin Peptides-Preparation, Bioactivity, Mechanistic Insights, and Strategies for Stability Improvement

Fish skin-derived gelatin has garnered significant attention recently due to its abundant availability and promising bioactive properties. This comprehensive review elucidates various intricacies concerning fish skin-derived gelatin peptides, including their preparation techniques, bioactive profiles, underlying mechanisms, and methods for stability enhancement. The review investigates diverse extraction methods and processing approaches for acquiring gelatin peptides from fish skin, emphasizing their impact on the peptide composition and functional characteristics. Furthermore, the review examines the manifold bioactivities demonstrated by fish skin-derived gelatin peptides, encompassing antioxidant, antimicrobial, anti-inflammatory, and anticancer properties, elucidating their potential roles in functional food products, pharmaceuticals, and nutraceuticals. Further, mechanistic insights into the functioning of gelatin peptides are explored, shedding light on their interactions with biological targets and pathways. Additionally, strategies aimed at improving the stability of gelatin peptides, such as encapsulation, modification, and integration into delivery systems, are discussed to extend the shelf life and preserve the bioactivity. Overall, this comprehensive review offers valuable insights into using fish skin-derived gelatin peptides as functional ingredients, providing perspectives for future research endeavors and industrial applications within food science, health, and biotechnology.

Physical and functional properties of fish gelatin-based film incorporated with mangrove extracts

Background

The fishery processing industry produces a remarkable number of by-products daily. Fish skin accounts for one of the significant wastes produced. Fish skin, however, can be subjected to extraction to yield gelatine and used as the primary raw material for edible film production. To increase the functionality of edible films, bioactive compounds can be incorporated into packaging. Mangroves produce potential bioactive compounds that are suitable as additional agents for active packaging. This study aimed to create a fish gelatine-based edible film enriched with mangrove extracts and to observe its mechanical and biological properties.

Methods

Two mangrove species (Bruguiera gymnorhiza and Sonneratia alba) with four extract concentrations (control, 0.05%, 0.15%, 0.25%, and 0.35%) were used to enrich edible films. The elongation, water vapour transmission, thickness, tensile strength, moisture content, antioxidant and antibacterial properties of the resulting packaging were analysed.

Results

The results showed that the mangrove species and extract concentration significantly affected (p < 0.05) the physical properties of the treated films such as elongation (16.89-19.38%), water vapour transmission (13.31-13.59 g/m²), and active packaging-antioxidant activities (12.36%-60.98%). The thickness, tensile strength, and water content were not significantly affected. Potent antioxidant activity and relatively weak antimicrobial activity of this active gelatine packaging were observed.

Effect of acid treatment on extraction yield and gel strength of gelatin from whiptail stingray (Dasyatis brevis) skin

Chemical properties of fish gelatins differ from those of conventional mammalian sources, representing an attractive technological alternative for the food industry. Ray filleting generates a considerable amount of skin waste that can be used as a collagen source for gelatin extraction. Thus, this research evaluated the HCl and CH₃COOH effect, at 0.01, 0.025, 0.05, 0.075, 0.1, 0.15, and 0.2 M, on extraction yield, molecular weight distribution, and gel strength (GS) of whiptail stingray (Dasyatis brevis) skin gelatins. Results showed differences (P < 0.05) between acid type and concentration used. CH₃COOH (0.15 M) gave the highest extraction yield (7.0% vs. 5.5% at 0.15 M HCl) and GS (653 ± 71 g vs. 619.5 ± 82 g at 0.2 M HCl). Gelatin electrophoretic profile from CH₃COOH revealed α-/β-components and high molecular weight (> 200 kDa) polymers. Ray gelatin GS was higher than commercial bovine gelatin, suggesting its possible use for technological food applications.

Antioxidant Activity of Collagen Extracts Obtained from the Skin and Gills of Oreochromis sp

Efforts aimed at reduction of fishing waste generated during the evisceration and filleting are scarce. The fishing waste is used in the production of low value-added products, such as flours or silages. It is important to visualize an alternative and profitable use of this waste, as it constitutes a serious environmental problem. This research determined the antioxidant properties of collagenous extracts of skin and galls of Oreochromis sp. The raw materials were characterized by proximal chemical analysis. Three treatments were applied to extract the collagen: salt-soluble collagen, acid-soluble collagen (ASC), and pepsin-hydrolyzed collagen (PHC). The collagenous fractions were hydrolyzed (0.1% pepsin). The recovered collagen yield and antioxidant activity were determined to hydrolyzed collagen (HC) and nonhydrolyzed collagen (NHC). The ASC skin showed the highest extraction yield (3.02%). For galls, only the PHC extraction was feasible (0.16%). Antioxidant analysis of NHC did not reveal radical scavenging activities. HC displayed a 2,2-diphenyl-1-picrylhydrazyl %RSA of 22.58 (ASC skin) and 10.34% (PHC galls), and a 2,2'-azino-bis[3-ethylbenzothiazoline-6-sulfonic acid] %RSA of 30.40% (PHC skin) and 29.43% (PHC galls), respectively. The ASC skin and PHC gall extracts exhibited 94.40% and 81.54% in ferric-reducing antioxidant power, and 43.63 and 38.08 μg ascorbic acid equivalents per milli liter for total antioxidant capacity, respectively. The collagen extracts showed %RSA and chelation of pro-oxidant metal ions. Different mechanism of antioxidant action was identified for the extracts: radical scavengers for HC and metal ion chelators for NHC. In conclusion, red tilapia skin collagen is recommended as an active ingredient of nutraceuticals, pharmaceuticals, or functional foods, for the identified bioactive properties.

Optimization of Gelatin Extraction and Physico-chemical Properties of Fish Skin and Bone Gelatin: Its Application to Panna Cotta Formulas

The utilization of fish processing waste for value-added by-products has attracted considerable attention. The present study aims to evaluate the gelatin extracted from fish skin and bone for application to Panna cotta products. The optimum conditions of gelatin extraction from Sea Bass, Nile tilapia and Red tilapia skin and bone were at 80 and 90 °C for 2.5 h, respectively. Nile tilapia skin and bone gelatins represent the most hydroxyproline content of 45.38 ±1.32 and 23.28±1.12 g, respectively (p0.05). Nile tilapia skin gelatin has the strength gel of 860.50 g which higher than Nile tilapia bone. The foaming ability normally increases at pH 3 to 6 and has emulsifier ability. Sodium chloride (NaCl) and activated carbon have effecting to remove the color and odor of extracted gelatin. Nile tilapia bone gelatin is the most suitable as an ingredient for Panna Cotta recipe. Panna Cotta milk mix berries has the maximum satisfaction levels in the female and male group of 4 to 5 (like very much to like extremely) for their flavor and texture by surveying satisfaction of customer in 5 points hedonic scale (30 persons). The average costs of production are between 0.56-0.71 US$/cup (200 g). Therefore, it can be concluded that fish gelatin can apply the ingredient in Panna Cotta Recipe or cook with another kind of foods. The extracted fish gelatin has desirable chemical and physical properties. It is suitable as a food ingredient which aspects as an alternative source of mammalian gelatin.

Molecular characteristics and properties of gelatin from skin of seabass with different sizes

Gelatin was extracted from the skin of seabass (Lates calcarifer) with different average sizes (2, 4 and 6 kg/fish), termed G2, G4 and G6, respectively and their characteristics and functional properties were determined. Yields of G2, G4 and G6 were 38.22, 40.50 and 43.48% (based on dry weight), respectively. G2 contained α-chains as dominant component, whilst G4 and G6 comprised α-, β- and γ-chains with a larger content of high MW cross-links. All gelatins had the similar imino acid (hydroxyproline and proline) content. Net charge of G2, G4 and G6 became zero at pH of 6.73, 6.41 and 7.12, respectively. Amongst all gelatin samples, G6 exhibited the highest gel strength (321.5 g) (p<0.05), but had the lowest turbidity (p<0.05). Gels of G6 sample had the lower L*-value but higher a*-, b*- and ΔE*-value, compared with others. Gelling and melting temperatures of all gelatins were 17.09-19.01 and 26.92-28.85 °C, respectively. Furthermore, all gelatins were able to set at room temperature, regardless of size of seabass used. G6 had the shorter setting time at room temperature than others. Therefore, size of seabass, in which skin was used for gelatin extraction, had the impact on yield, composition and properties of resulting gelatin.

Collagen Extraction from Malaysian Cultured Catfish (Hybrid Clarias Sp.): Kinetics and Optimization of Extraction Conditions Using Response Surface Methodology

A central composite design (CCD) was used for the experimental design and results analysis to obtain the optimal processing parameters (acetic acid concentration, liquid to solid ratio, and stirring speed) for the extraction of pepsin soluble collagen (PSC) from muscles of cultured hybrid catfish of Clarias sp. (Clarias gariepinus × C. macrocephalus). Statistical analysis showed that the linear and quadratic terms of these three independent variables had significant effects on the yield of PSC. There was also an interaction between the ratio of liquid to solid and the stirring speed in affecting the extraction efficiency. Optimal conditions for a higher yield of PSC were an acetic acid concentration of 0.67 M, a liquid to solid ratio of 24.65 ml/g, and the stirring speed of 423.64 rpm. The verification of the optimization showed that the percentage error differences between the experimental and predicted values were in the range of 0.22–4.42%. The experimental values agreed with the predicted values, indicating an excellent fit of the model used and the success of the response surface methodology in modeling the extraction of PSC from the muscles of catfish. The experimental results were also fitted to the power law model and it was proven to be appropriate in describing the kinetics of collagen extraction process.