Effect of different acids on the extraction of pepsin-solubilised collagen containing melanin from silky fowl feet

Comparing solution blow spinning and electrospinning methods to produce collagen and gelatin ultrathin fibers: A review

Ultrathin fibers have been used to design functional nanostructured materials for technological and biomedical applications. Combining the use of renewable and compatible sources with the emerging alternative SBS (solution blow spinning) technique opens new opportunities for material applications. In this review, we introduce the benefits of SBS over the classical electrospinning technique by following studies that use collagen or gelatin. SBS offers distinct advantages over electrospinning in the preparation of ultrathin fibers based on natural proteins, including the absence of high-voltage sources and the possibility of using fewer toxic solvents. Notably, there is also the prospect of using SBS directly in injured tissues, opening new strategies for in situ structure assembly SBS is a suitable approach to produce fibers at the nanoscale that can be tailored to distinct diameters by blending or simply adjusting experimental conditions. The focus on producing collagen or gelatin fibers contributes to designing highly biocompatible mats with potential for promoting cellular growth and implantation, even though their applications can be found also in food packaging, energy, and the environment. Therefore, a comprehensive analysis of the topic is essential to evaluate the current strategies regarding these materials and allow for their expanded production and advanced applications.

Changes in Texture and Collagen Properties of Pork Skin during Salt-Enzyme-Alkali Tenderization Treatment

The effects of salt-enzyme-alkali progressive tenderization treatments on porcine cortical conformation and collagen properties were investigated, and their effectiveness and mechanisms were analyzed. The tenderization treatment comprised three treatment stages: CaCl2 (25 °C/0-30 min), papain (35 °C/30-78 min), and Na2CO3 (25 °C/78-120 min). The textural, microscopic, and collagenous properties (content, solubility, and structure) of pork skin were determined at the 0th, 30th, 60th, 90th, and 120th min of the treatment process. The results showed that the shear force, hardness, and chewability of the skin decreased significantly (p < 0.05), and the elasticity exhibited a gradual increase with the progression of tenderization. The content and solubility of collagen showed no significant change at the CaCl2 treatment stage. However, the soluble collagen content increased, the insoluble collagen content decreased, and the collagen solubility increased by 18.04% during the subsequent treatment with papain and Na2CO3. Meanwhile, the scanning electron microscopy results revealed that the regular, wavy structure of the pig skin collagen fibers gradually disappeared during the CaCl2 treatment stage, the overall structure revealed expansion, and the surface microscopic pores gradually increased during the papain and Na2CO3 treatment stages. The findings of the Fourier transform infrared spectroscopy analysis indicated that the hydrogen bonding interactions between the collagen molecules and the C=O, N-H and C-N bonds in the subunit structure of collagen were substantially altered during treatment and that the breakage of amino acid chains and reduction in structural ordering became more pronounced with prolonged treatment. In the tertiary structure, the maximum emission wavelength was blue-shifted and then red-shifted, and the fluorescence intensity was gradually weakened. The surface hydrophobicity was slowly increased. The salt-enzyme-alkali tenderization treatment considerably improved the physical properties and texture of edible pork skins by dissolving collagen fibers and destroying the structure of collagen and its interaction force.

Structural and molecular characterization of collagen-type I extracted from lamb feet

This study aimed to extract collagen-I from lamb feet (LF) and examine the effects of ultrasound treatment on the structural and molecular characteristics of the collagen. Compared to ultrasonic bath treatment and conventional extraction methods, ultrasonic probe (USP) treatment significantly increased the collagen content of the extract (p < 0.05). The electrophoretic profiles confirmed the presence of α- and β-chains, indicating it as type I. Furthermore, X-ray diffraction, Fourier-transform infrared spectroscopy, and circular dichroism spectra analyses revealed that the extraction method did not adversely affect the triple helix structure of the collagen. Moreover, the fibrillar structure of the collagen samples was verified through scanning electron microscopy analyses. Notably, the LF collagen exhibited a high thermal denaturation temperature owing to its elevated imino acid content. The collagen samples exhibited high solubility in acidic pH but low solubility in high salt concentrations. The present findings signified that sonication with USP can effectively enhance the yield of collagen from LF without compromising its quality. PRACTICAL APPLICATION: This study showed that ultrasonication enhanced the collagen concentration without disturbing the integrity of lamb feet collagen. We expect that lamb feet collagen can be used for industrial processes and consumer products thanks to unique product properties.

Mechanism behind the deterioration in gel properties of collagen gel induced by high-temperature treatments: A molecular perspective

This study aims to elucidate the mechanism behind the deterioration in the gel properties of collagen gel resulting from high-temperature treatment. The results show that the high level of triple-helix junction zones and related lateral stacking contribute to the dense and orderly collagen gel network with high gel strength and storage modulus. The analysis of the molecular properties of heated collagen shows that high-temperature treatment leads to serious denaturation and degradation of collagen, resulting in the formation of gel precursor solutions composed of low-molecular-weight peptides. The short chains in the precursor solution are not easy to nucleation and can limit the growth of triple-helix cores. To conclude, the decrease in triple-helix renaturation and crystallization abilities of peptide components is the reason for the deterioration in the gel properties of collagen gel induced by high temperature. The findings presented in this study add the understanding of texture deterioration in high-temperature processed collagen-based meat products and related products, and provide a theoretical basis for establishing methods to overcome the production dilemma faced by these products.

Effects of Pig Skin Collagen Supplementation on Broiler Breast Meat

This study aimed to enhance the quality of broiler breast meat by adding pig skin collagen to feed. A total of 50 Ross 308 broilers were classified according to the following feeding regime for two weeks: basal diet (NC), basal diet+0.1% fish collagen (PC), basal diet+0.1% pig skin collagen (T1), basal diet+0.5% pig skin collagen (T2), and basal diet+1.0% pig skin collagen (T3). The moisture content was the highest in the PC group, and the protein content was the lowest in the T1 group (p<0.05). The fat content was higher in the T1 and PC groups, whereas the ash content was higher in the T3 group (p<0.05). Drip loss was the highest in the NC group and the lowest in the T2 group (p<0.05). Lightness was low in groups T2 and T3, redness was low in groups T2 and PC, and yellowness was low in groups T1, T2, and PC (p<0.05). The collagen content of the chicken breast was the highest in the T3 group, and that of the skin was the highest in the T1 group (p<0.05). The texture characteristics of springiness, cohesiveness, chewiness, and hardness were the highest in the T3 group (p<0.05). In conclusion, the supplementation of a broiler diet with pig skin collagen was found to increase the collagen content of the breast meat, indicating the improved quality of the broiler breast meat.

Collagen based electrospun materials for skin wounds treatment

Materials used for wound care have evolved from simple covers to functional wound dressings with bioactive properties. Electrospun nanofibers show great similarity to the natural fibrillar structure of skin extracellular matrix (ECM); therefore, by mimic, the morphology of ECM, nanofibers show high potential for facilitating the healing of skin injuries. Besides morphology, scaffold composition is another important parameter in the production of bioactive wound dressings. Collagen type I is the main structural protein of skin ECM is biocompatible, biodegradable, and its extraction from animal sources is relatively simple. The fabrication of electrospun wound dressings based on collagen and its blends have been studied for skin tissue engineering applications. This review focus on the new advances of collagen electrospun materials for skin wound treatment. It summarizes the recent research on pristine collagen, collagen blends, and collagen surface modifications on nanofibers mats. Finally, the strategies for three-dimensional nanofibers production will also be discussed.

Preparation of protein products from collagen-rich poultry tissues

Chicken stomachs are by-products obtained from the poultry processing in slaughterhouses. Their amount has been gradually increasing as a consequence of a continually rising poultry consumption. Since these animal tissues are still rich in proteins, mainly collagen, fat, and minerals, it is essential and beneficial to investigate the appropriate management and further processing. Collagen could be extracted from chicken stomachs and used as a raw material in the food, cosmetic, medical, and also pharmaceutical industry. This paper is to investigate possibilities of such extraction of collagen products, gelatines, or alternatively hydrolysates, from chicken stomachs after prior biotechnological treatment with the proteolytic enzyme Protamex. In this experiment, non-collagenous proteins were removed from stomachs using 0.03 M NaOH and 0.2 M NaCl. Subsequently, the tissue was defatted applying acetone and the enzyme Lipolase. Purified and dried collagen was then treated with the proteolytic enzyme Protamex. In the last step, gelatine was extracted from the tissue in hot water. The influence of selected processing parameters on the extraction efficiency and final product quality was monitored. The extraction conditions included the amount of the added enzyme (0.1 – 0.4%) and the extraction temperature of between 60 and 65 °C. The total gelatine yield ranged from 43.80 to 96.45% and the gel strength varied from 2 ±0 to 429 ±8 Bloom. The enzymatic treatment of the raw material is an economical and ecological alternative to traditional acid or alkaline treatments. Extracted gelatine with the gel strength of 100 – 300 Bloom would be suitable for the applications in the food industry in the production of confectionery, marshmallow, aspic or dairy products.

Sea Cucumber Derived Type I Collagen: A Comprehensive Review

Collagen is the major fibrillar protein in most living organisms. Among the different types of collagen, type I collagen is the most abundant one in tissues of marine invertebrates. Due to the health-related risk factors and religious constraints, use of mammalian derived collagen has been limited. This triggers the search for alternative sources of collagen for both food and non-food applications. In this regard, numerous studies have been conducted on maximizing the utilization of seafood processing by-products and address the need for collagen. However, less attention has been given to marine invertebrates and their by-products. The present review has focused on identifying sea cucumber as a potential source of collagen and discusses the general scope of collagen extraction, isolation, characterization, and physicochemical properties along with opportunities and challenges for utilizing marine-derived collagen.

Extraction and characterization of gelatin from black-bone chicken by-products

In this study, gelatins from black-bone chicken feet and skin (BCFG and BCSG) were extracted using different NaOH concentrations, and their physicochemical properties were characterized and compared to commercial bovine gelatin (BG). It was found that the yield of BCFG was higher than BCSG, however, it contained higher amount of ash. All studied gelatins were composed of two distinct α-chains, while β-chain and γ-chain were not present. The BCFG and BCSG were found to have lower pH, lower hydroxyproline content and lower thermal stability, but higher gel strength as compared with the BG. The colors of BCSG and BCSG were slightly darker than BG. The NaOH concentration did not show strong influence on physicochemical properties of the extracted gelatins, however, thermal stability and gel strength of BCSG tended to decrease with increasing of NaOH concentration. These findings suggested that black-bone chicken feet and skin could be a great source for the production of gelatin.

Biotechnological Preparation of Gelatines from Chicken Feet

In the European Union (EU), about five tons of poultry by-product tissues are produced every year. Due to their high collagen content, they represent a significant raw material source for gelatine production. The aim of the paper was the biotechnological preparation of gelatine from chicken feet. The influence of selected process factors on the gelatine yield, gel strength, viscosity, and ash of gelatine was observed; a two-level factor design of experiments with three variable process factors (enzyme addition, enzyme treatment time, and gelatine extraction time) was applied. After grinding and separating soluble proteins and fat, the purified raw material was treated in water at pH 7.5 with the addition of endoprotease at 23 °C and after thorough washing with water at 80 °C, gelatine was extracted. By the suitable choice of process conditions, gelatine with high gel strength (220–320 bloom), low ash content (<2.0%) and viscosity of 3.5–7.3 mPa·s can be prepared. The extraction efficiency was 18–38%. The presented technology is innovative mainly by the enzymatic processing of the source raw material, which is economically, technologically, and environmentally beneficial for manufacturers. Chicken gelatines are a suitable alternative to gelatines made from mammals or fish, and can be used in many food, pharmaceutical, and biomedical applications.

Effect of Orally Administered Collagen Peptides from Bovine Bone on Skin Aging in Chronologically Aged Mice

Collagen peptides (CPs) have demonstrated to exert beneficial effects on skin photoaging. However, little has been done to evaluate their effects on chronologically aged skin. Here, the effects of CPs from bovine bone on skin aging were investigated in chronologically aged mice. 13-month-old female Kunming mice were administered with CPs from bovine bone (200, 400 and 800 mg/kg body weight/day) or proline (400 mg/kg body weight/day) for 8 weeks. Mice body weight, spleen index (SI) and thymus index (TI), degree of skin laxity (DSL), skin components, skin histology and antioxidant indicators were analyzed. Ingestion of CPs or proline had no effect on mice skin moisture and hyaluronic acid content, but it significantly improved the skin laxity, repaired collagen fibers, increased collagen content and normalized the ratio of type I to type III collagen in chronologically aged skin. CPs prepared by Alcalase performed better than CPs prepared by collagenase. Furthermore, CPs intake also significantly improved the antioxidative enzyme activities in skin. These results indicate that oral administration of CPs from bovine bone or proline can improve the laxity of chronologically aged skin by changing skin collagen quantitatively and qualitatively, and highlight their potential application as functional foods to combat skin aging in chronologically aged process.

The effect of collagen hydrolysates from silver carp (Hypophthalmichthys molitrix) skin on UV-induced photoaging in mice: molecular weight affects skin repair

The use of collagen hydrolysates (CHs) as a nutraceutical agent in skin aging has gained increasing attention. Here, the effects of various doses and molecular weights of CH from silver carp skin on photoaging in mice were investigated. The ingestion of CH at 50, 100 and 200 mg per kg body weight led to a dose-dependent increase in the hydroxyproline, hyaluronic acid and moisture contents of the skin, but it had no significant effect on the mice body weight, or on the spleen or thymus index. Furthermore, ingesting CH with lower (LMCH, 200-1000 Da, 65%) and higher molecular weight (HMCH, >1000 Da, 72%) significantly increased the skin components and improved the antioxidative enzyme activities in both serum and skin (p < 0.05); LMCH performed better than HMCH. By contrast, gelatin (>120 kDa) ingestion did not bring a significant change compared to model mice. These results indicated that LMCH exerted a stronger beneficial effect on the skin than did either HMCH and gelatin, which supported the feasibility of using LMCH as a dietary supplement from silver carp skin to combat photoaging.

Extraction optimization of pepsin-soluble collagen from eggshell membrane by response surface methodology (RSM)

Response surface methodology (RSM) was used to investigate the effect of extraction-process variables on pepsin-soluble collagen (PSC) from eggshell membrane. A central composite design (CCD) was employed for experimental design and analysis of the results to obtain the best possible combination of NaOH concentration (X1: 0.4-1.2 mol/l), alkali treatment time (X2: 6-30 h), enzyme concentration (X3: 15-75 U/mg) and hydrolysis time (X4: 12-60 h) for maximum PSC extraction. The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis and analyzed by appropriate statistical methods. According to the results, optimum extraction conditions were as follows: NaOH concentration of 0.76 mol/l, alkali treatment time of 18 h, enzyme concentration of 50 U/mg and hydrolysis time of 43.42 h. The experimental extraction yield under optimal conditions was found to be 30.049%, which is in good agreement with the predicted value of 30.054%.