Kinetic modeling of the alkaline deproteinization of Nile-tilapia skin for the production of collagen

Marine collagen: Unveiling the blue resource-extraction techniques and multifaceted applications

Marine organisms such as fish and shellfish are composed of compounds with properties and characteristics that have been proven useful in a variety of sectors such as cosmetics, healthcare (wound healing), food industries, and tissue engineering. Collagen extraction from fish waste as a "blue resource" has attracted research attention over the past decade. Around 75 % of fish waste contains a high concentration of collagen. This has driven research in the conversion of these low-cost by-products into valuable products. Collagen extracted by acidic or/and enzymatic methods is gaining a lot of attention today due to its low cost and high yield. Fermentation and enzymatic hydrolysis stand out as one of the most environmentally sustainable and ecologically friendly methods for collagen extraction. Because of its great biocompatibility, excellent bioactivity, and low antigenicity, marine collagen is receiving more attention. Furthermore, collagen-derived peptides may exhibit interesting antioxidant activity, potent antihypertensive activity, and antimicrobial activity against different strains of bacteria. This review focuses on the advancements in extraction and detection methods of marine collagen, both from a technological and legislative standpoint, in addition to exploring its diverse range of application domains.

Removal of collagen three-dimensional scaffold bubbles utilizing a vacuum suction technique

The process of generating type I/II collagen scaffolds is fraught with bubble formation, which can interfere with the three-dimensional structure of the scaffold. Herein, we applied low-temperature vacuum freeze-drying to remove mixed air bubbles under negative pressure. Type I and II rubber sponges were acid-solubilized via acid lysis and enzymolysis. Thereafter, vacuum negative pressure was applied to remove bubbles, and the cover glass press method was applied to shape the type I/II original scaffold. Vacuum negative pressure was applied for a second time to remove any residual bubbles. Subsequent application of carbamide/N-hydroxysuccinimide cross-linked the scaffold. The traditional method was used as the control group. The structure and number of residual bubbles and pore sizes of the two scaffolds were compared. Based on the relationship between the pressure and the number of residual bubbles, a curve was created, and the time of ice formation was calculated. The bubble content of the experimental group was significantly lower than that of the control group (P < 0.05). The pore diameter of the type I/II collagen scaffold was higher in the experimental group than in the control group. The time of icing effect of type I and II collagen solution was 136.54 ± 5.26 and 144.40 ± 6.45 s, respectively. The experimental scaffold had a more regular structure with actively proliferating chondrocytes that possessed adherent pseudopodia. The findings indicated that the vacuum negative pressure method did not affect the physical or chemical properties of collagen, and these scaffolds exhibited good biocompatibility with chondrocytes.

Properties and Characteristics of Acid-Soluble Collagen from Salmon Skin Defatted with the Aid of Ultrasonication

Salmon skin, a byproduct from the deskinning process, can be used as an alternative source of collagen. Due to the high fat content in skin, the defatting process is required prior to extraction. The properties and characteristics of acid-soluble collagen (ASC) from salmon skin (Oncorhynchus nerka), defatted using isopropanol without and with ultrasonication (70% amplitude for 10 min), were investigated. The ASC from the skin that was defatted with aid of ultrasonication (U-ASC) exhibited lower (p < 0.05) fat content (1.86%) with extraction yield (23.18% w/w, dry weight basis). U-ASC had a higher hydroxyproline content (49.15 mg/g dry sample) and maximum transition temperature (Tmax) (11.6 °C) than C-ASC (collagen extracted from skin defatted without ultrasonication). Both of the ASCs were classified as type I collagen. C-ASC and U-ASC had isoelectric points of 7.17 and 7.40, respectively. Fourier transform infrared (FTIR) and circular dichroism spectra reconfirmed the triple-helix structure of both ASCs. The major amino acid of both collagens was glycine (297–308 residues/1000 residues). A high amount of imino acid (191–193 residues/1000 residues) was also found. After gastrointestinal digestion, the degree of hydrolysis of the digested U-ASC (23.19%) was slightly higher than that of the digested C-ASC (22.31%). However, both digests had no differences in antioxidant activities. Both of the ASCs could be therefore used as functional ingredient.

Characterization of Collagen from Three Genetic Lines (Gray, Red and F1) of Oreochromis niloticus (Tilapia) Skin in Young and Old Adults

From tilapia (Oreochromis niloticus) farming, the by-products have been identified as a source of collagen that could be used for the development of dermocosmetics or pharmaceutical products. However, the characteristics of collagen related to a specific strain or culture must be well defined prior to its application. Collagen was extracted from the skin of three strains of tilapia: red YY males (YY: two Y-type sex chromosomes), XX gray females, and the F1: offspring of crossing red YY males with XX gray females; at different ages in the adult phase, using acetic acid and pepsin enzyme. The characteristics of acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were shown by SDS-PAGE band profiles to be similar to bovine collagen type I (SIGMA), the PSC of gray tilapia being more fragile to temperature changes, consistent with the results of fractional viscosity. The characteristics of the F1 progeny were prioritized for being a commercially productive and sustainable source for the extraction of collagen, and the ASC form, being the one with the greatest stability and advantage over PSC, of importance to our investigations, leads to a controlled digestion as in the case of peptide induction, and also in the development of natural products in the pharmaceutical and/or dermocosmetic industry. Evaluations of the triple helix structure by FT-IR, X-ray diffraction and UV-visible spectroscopy give similar results between the strains: red, gray, and F1, and between ages in the adult form F1 (15, 24, and 36 months of age). Consequently, the skin of tilapia in adult form is recommended sustainably for up to 24 months of age where the collagen is obtained with the use of acetic acid without enzymatic treatment.