FUNCTIONAL PROPERTIES OF CATFISH SKIN COLLAGEN HYDROLYSATES

Collagen hydrolysates were obtained from catfish skin collagen hydrolysis using catfish collagenase, pepsin and trypsin individually and mixed for 15-300min. The degree of hydrolysis , antioxidant activity based on, DPPH radical-scavenging activity (RSA), and reducing power (RP) for all obtained hydro lysates were studied , then the collagenase hydrolysate was (CH) was selected to be evaluated for antibacterial activity , functional properties including solubility, emulsification and foaming properties besides the toxicity . The highest values for RSA (72.5%) has been noticed when DH reached (24.30%) after 30 min. of hydrolysis by collagenase (CH). The water and oil holding capacities for this hydro lysate was compared to that for ASC (acid soluble collagen and PSC (pepsin soluble collagen), the results showed that the values recorded by CH were significantly higher than ASC & PSC. The molecular weight of CH peptides ranged from 180 to 11 Da. as analyzed by SDS- PAGE. The toxicity assay result revealed that CH is safe for human consumption. There was no antibacterial function for CH toward E.coli and S. aureus. At concentration of 2mg/ml. This study suggests that catfish collagen hydro lysate could be a good natural alternative for synthetic antioxidants in food industries.

Preparation and Characterization of Thermally Stable Collagens from the Scales of Lizardfish (Synodus macrops)

Marine collagen is gaining vast interest because of its high biocompatibility and lack of religious and social restrictions compared with collagen from terrestrial sources. In this study, lizardfish (Synodus macrops) scales were used to isolate acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC). Both ASC and PSC were identified as type I collagen with intact triple-helix structures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and spectroscopy. The ASC and PSC had high amino acids of 237 residues/1000 residues and 236 residues/1000 residues, respectively. Thus, the maximum transition temperature (Tmax) of ASC (43.2 °C) was higher than that of PSC (42.5 °C). Interestingly, the Tmax of both ASC and PSC was higher than that of rat tail collagen (39.4 °C) and calf skin collagen (35.0 °C), the terrestrial collagen. Solubility tests showed that both ASC and PSC exhibited high solubility in the acidic pH ranges. ASC was less susceptible to the “salting out” effect compared with PSC. Both collagen types were nontoxic to HaCaT and MC3T3-E1 cells, and ASC was associated with a higher cell viability than PSC. These results indicated that ASC from lizardfish scales could be an alternative to terrestrial sources of collagen, with potential for biomedical applications.

Effects of radiation dose and nitrogen purge on collagen scaffold properties

Sterilization of medical devices is commonly performed using radiation methods. However, collagen materials can be damaged when using standard radiation doses (25 kGy). Small increases of radiation dose can allow for increases in the acceptable initial bioburden load of aseptically manufactured devices while maintaining required sterility assurance levels, which is often critical in early stage translational settings. In this study, we hypothesized that small increases in radiation dose from 15 to 20 kGy would result in significant changes to several key characteristics of collagen scaffolds. Scaffolds were manufactured by lyophilizing the pepsin digest of dense bovine connective tissue in cylindrical molds and were irradiated at either 0, 15, 17.5, or 20 kGy with an additional group packaged in nitrogen and irradiated at 17.5 kGy. Groups were evaluated for changes to the soluble collagen and glycosaminoglycan mass fractions, protein banding patterns in electrophoresis, a collagen fragmentation assay, and resistance to enzymatic degradation. All parameters were statistically analyzed using one-way analysis of variance with Tukey’s correction for multiple comparisons. The soluble collagen mass fraction was significantly decreased in the 20 kGy group; however, there was no significant effect of radiation dose or a nitrogen-rich environment on the other measured parameters, including protein banding patterns, fragmented collagen content, and resistance to enzymatic degradation. Statement of Clinical Significance: Collagen scaffolds have proven useful in clinical applications but can be damaged by standard radiation doses. Low-dose sterilization may be a viable alternative that minimally impacts key properties of these scaffolds.

Isolation and properties of collagen extracted from mixed by-products obtained from different fish species

Fish by-products consisting of skin, bones, or scales are collagen sources. Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) mixed by-products derived from different fish species were extracted and evaluated. The properties evaluated for both collagens were chemical composition, amino acid- and SDS-PAGE- protein profiles, Fourier transform infrared spectroscopy (FTIR), denaturation temperature (Tmax), enthalpy (ΔH), and solubility. The ASC and PSC registered a protein content of 48.56 and 38.80 %, respectively. From the total amino acids detected, hydroxyproline accounted for 7 % and 6 % for ASC and PSC, respectively. The electrophoretic profile showed the presence of the type I collagen bands (α1, α2, β, and γ), whereas FTIR spectrum showed the presence of diverse collagen functional groups (Amide A, B, I, II, and III) for both extracted types, and demonstrated that the extraction process did not affect the collagen´s triple-helical structure. The Tmax of ASC and PSC were 38.27 and 38.07° C, respectively, whereas ΔH were 0.64 and 0.33 J g-1. The lowest solubility was registered at pH 5 for ASC and pH 9 for PSC. The caractheristics of the collagen extracted, indicated that a mixture of by-products from different species could be an alternative for their reutilization by the local markets.

Characterization of Acid-Soluble Collagen from Food Processing By-Products of Snakehead Fish (Channa striata)

The isolation of acid-soluble collagen (ASC) from by-products of snakehead fish (Channa striata), including skin and the mixture of skin and scale, has been investigated. The recovery yield of fish skin ASC (13.6%) was higher than ASC from fish skin and scale (12.09%). Both ASCs were identified as type I collagen and showed maximal solubility at pH 2. Collagen samples from the mixture of skin and scale had higher imino acid content (226 residues/1000 residues) and lower wavenumber in the amide I and amide III region (1642 and 1203 cm−1, respectively) than the fish skin ASC (the imino acid content was 220 residues/1000 residues and the wavenumber in the amide I and amide III were 1663 and 1206 cm−1, respectively. The difference scanning calorimeter (DSC) showed higher thermal stability in ASC from the mixture of skin and scale (Td of 35.78 °C) than fish skin ASC (34.21 °C). From the result, the denaturation temperature of ASC had a close relationship with the content of imino acid as well as with the degradation of α-helix in amide I and III. These results suggest that collagen could be obtained effectively from snakehead fish by-products and has potential as a realistic alternative to mammalian collagens.