Physicochemical properties of gelatin extracted from chicken deboner residue

A Review of Modified Gelatin: Physicochemical Properties, Modification Methods, and Applications in the Food Field

Gelatin is a significant multifunctional biopolymer that is widely utilized as a component in food, pharmaceuticals, and cosmetics. Numerous functional qualities are displayed by gelatin, such as its exceptional film-forming ability, gelling qualities, foaming and emulsifying qualities, biocompatibility and biodegradable qualities. Due to its unique structural, physicochemical, and biochemical characteristics, which enhance nutritional content and health benefits as well as the stability, consistency, and elasticity of food products, gelatin is utilized extensively in the food business. Additionally, gelatin has demonstrated excellent performance in encapsulating, delivering, and releasing active ingredients. Gelatin's various modifications, such as chemical, enzymatic, and physical processes, were analyzed to assess their impact on gelatin structures and characteristics. Hopefully, gelatin will be more widely used in various applications after modification using suitable methods.

Extraction and physicochemical characterization of native and broiler chicken feet gelatin

BACKGROUND

Poultry processing generates a large amount of industrial waste, which is rich in collagen content. This waste can be utilized for the extraction of valuable components such as gelatin, which can be used as an alternative to mammalian gelatin (porcine and bovine).

RESULTS

Gelatins were analyzed for their yield, proximate analysis, pH, color, viscosity, bloom strength, and texture profile analysis. The yield of broiler chicken feet gelatin (BCFG) was slightly higher (7.93%) as compared to native chicken feet gelatin (NCFG) (7.06%). The protein content was 85.92% and 82.53% for BCFG and NCFG. Both gelatin had moisture content in the standard range (< 15) as given by Gelatin Manufacturers of Europe (GME). Both gelatins showed higher bloom strength (326 g for NCFG and 203 g for BCFG) at 6.67% gelatin concentration, classified as high bloom. Fourier-transform infrared (FTIR) analysis showed amide I, amide A, amide B at 1636 cm-1, 3302 cm-1, 2945 cm-1 for NCFG and 1738 cm-1, 3292 cm-1, 2920 cm-1 for BCFG. At 6.67% gelatin concentration, hardness and cohesiveness values were also higher than commercial gelatin previously studied. The pH values for NCFG were 5.43 and BCFG was 5.31. Both NCFG and BCFG viscosities (4.43 and 3.85 cP) were in the optimum range of commercial gelatins (2-7 cP).

CONCLUSION

Hence, the present study concluded that both NCFG and BCFG have a huge potential to replace commercial mammalian gelatins (porcine and bovine) in the food industries. However further studies should be done to optimize the extraction process. © 2024 Society of Chemical Industry.

Textural, rheological, and structural properties of turkey and chicken gelatins from mechanical deboning residues

Large amounts of collagen-rich by-products are generated in poultry processing. In particular, gelatin from the by-products of turkey processing is limited. Gelatin extraction from turkey and chicken MDRs (mechanically deboning residue) was the purpose of this study. Both materials were modified at the highest swelling pH for chemical denaturation of collagen and hot water extraction of gelatin was performed at the optimum temperature-time, which was determined to be pH 1.0 and 80°C-6 h, respectively. In these conditions, yields of 9.90% turkey gelatin (TG) and 13.85% chicken gelatin (CG) were produced. They demonstrated similar viscosity, gel strength, and lightness values of 72-73 g, 2.5-2.7 mPas, and 31, respectively. These results are close to those of bovine gelatin (BG). TG with 239.78 g Bloom exhibited higher strength than CG (225.27 g) and BG (220.00 g). The melting and gelation temperatures of CG and BG were 21 and 30°C, respectively, while those of TG were 19 and 28°C. Imino acids (proline + hydroxyproline) of TG (22.82%) were higher than those of CG (20.73%). Fourier transform infrared spectroscopy (FTIR) analysis revealed secondary structure and functional groups of CG and TG similar to those of BG. CG displayed a higher thermal transition temperature than BG, while TG exhibited the highest temperature sensitivity, according to the differential scanning calorimetry (DSC) analysis. In conclusion, TG showed higher potential for effective utilization with higher bloom and imino acids. Overall, turkey and chicken MDRs are a promising and potential alternative source to produce gelatin with comparable properties to bovine gelatin for intended food applications as well as for pharmaceutical and cosmetic fields.

Influence of gelatin type on physicochemical properties of electrospun nanofibers

This study explores the fabrication of nanofibers using different types of gelatins, including bovine, porcine, and fish gelatins. The gelatins exhibited distinct molecular weights and apparent viscosity values, leading to different entanglement behavior and nanofiber production. The electrospinning technique produced nanofibers with diameters from 47 to 274 nm. The electrospinning process induced conformational changes, reducing the overall crystallinity of the gelatin samples. However, porcine gelatin nanofibers exhibited enhanced molecular ordering. These findings highlight the potential of different gelatin types to produce nanofibers with distinct physicochemical properties. Overall, this study sheds light on the relationship between gelatin properties, electrospinning process conditions, and the resulting nanofiber characteristics, providing insights for tailored applications in various fields.

Optimization of Gelatin Extracting Condition from Korean Native Black Goat Skin and Quality Comparison with Commercial Gelatin

The practical use of Korean native black goat skin as a source of gelatin extraction is limited. The objective of this study was to optimize the extraction temperature and time of gelatin from Korean native black goat skin, and to compare the quality characteristics of goat skin gelatin and other commercial gelatin products. Response surface methodology was applied to optimize the extraction temperature and time of gelatin obtained from native Korean black goat skin. The effects of temperature (50°C-70°C) and time (2-4 h) on extraction yield and gel strength were investigated using a face-centered central composite design with 13 experiments. Gelatin extraction from Korean native black goat skin was prepared through the serial processes of alkali pre-treatment, bleaching, neutralization, hot-water extraction, and freeze-drying. Using the optimization plot of Minitab software, the optimized conditions for extracting temperature and time of goat skin gelatin were 59.49°C and 3.03 h, and the optimized values of extraction yield and gel strength were 12.52% and 263.37 g, respectively. Based on a quality comparison of goat skin gelatin with commercial gelatin, the pH value of gelatin extracted from Korean native black goat skin was 5.57. The color of gelatin extracted from Korean native black goat skin was darker than that of commercial gelatin (p<0.05). Higher emulsifying properties and gel strength of goat skin gelatin were observed when compared to those of commercial gelatin (p<0.05). Therefore, the results of this study indicate that Korean native black goat skin may be a valuable source for gelatin extraction.

Gelatin-based cellular solids: Fabrication, structure and properties

Although most cellular polymers are made from thermoplastics using different foaming technologies, gelatin and many other natural polymers can form hydrogels and convert them to cellular solids using various techniques, many of which differ from traditional plastic foaming, and so does their resulting structures. Cellular solids from natural hydrogels are porous materials that often exhibit a combination of desirable properties, including high specific surface area, biochemical activity, as well as thermal and acoustic insulation properties. Among natural hydrogels, gelatin-based porous materials are widely explored due to their availability, biocompatibility, biodegradability and relatively low cost. In addition, gelatin-based cellular solids have outstanding properties and are currently subject to increasing scientific research due to their potential in many applications, such as biocompatible cellular materials or biofoams to facilitate waste treatment. This article aims at providing a comprehensive review of gelatin cellular solids processing and their processing-properties-structure relationship. The fabrication techniques covered include aerogels production, mechanical foaming, blowing agents use, 3D printing, electrospinning and particle leaching methods. It is hoped that the assessment of their characteristics provides compiled information and guidance for selecting techniques and optimization of processing conditions to control material structure and properties to meet the needs of the finished products.

Rheological and functional characterization of gelatin and fat extracted from chicken skin for application in food technology

Chicken skin is a major byproduct of the poultry industry. This study was undertaken to extract and characterize fat and gelatin from chicken skin. To do this, the chicken skin was wet-rendered at different temperature-time combinations and the yield and properties of the extracted gelatin and fat were determined. Gelatin and fat were recovered at yield ranges of 0.74%-2.03% and 24.01%-27.91%, respectively. The time and the interaction of time-temperature had a positive effect on gelatin yield (p < .05); however, the fat yield was not affected by the extraction condition. Protein, ash, and hydroxyproline content of gelatin and unsaponifiables and free fatty acids contents, peroxide value, and induction period of oxidation of the fat were affected by the extraction condition. Functional and rheological analyses showed chicken skin gelatin gel/solution had a higher bloom value, viscosity, foaming capacity, storage and loss moduli, and melting and gelling points than the commercial bovine gelatin. Oleic (42.13%), palmitic (24.6%), and linoleic (17.53%) acids were the main fatty acids of chicken skin fat. The storage modulus of chicken skin fat was higher than the loss modulus up to 31°C; however, because of a low slip melting point (22.74°C) and solid fat content, it was fluid at room temperature. The findings of this research can be useful in the development of processes for the extraction and application of chicken skin gelatin and fat.

Characterization and functional properties of gelatin from goat bone through alcalase and neutrase enzymatic extraction

Background and Aim:

Gelatin is a dissolved protein that results from partial extraction of collagen, commonly from pig and bovine skin. There was no study on gelatin production from Kacang goat bones through enzymatic extraction. This study aimed to evaluate the chemical, physical, and functional properties of gelatin from bones of Kacang goat using alcalase and neutrase enzymes.

Materials and Methods:

Male Kacang goat bones aged 6-12 months and two commercial enzymes (alcalase and neutrase) were used for this study. Descriptive analysis and completely randomized design (one-way analysis of variance) were used to analyze the chemical, physical, and functional properties of gelatin. Kacang goat bone was extracted with four concentrations of alcalase and neutrase enzymes, namely, 0 U/g (AG-0 and NG-0), 0.02 U/g (AG-1 and NG-1), 0.04 U/g (AG-2 and NG-2), and 0.06 U/g (AG-3 and NG-3) with five replications.

Results:

The highest yield of gelatin extraction with alcalase obtained on AG-3 was 9.78%, and that with neutrase on NG-3 was 6.35%. The moisture content of alcalase gelatin was 9.39-9.94%, and that of neutrase gelatin was 9.15-9.24%. The ash and fat content of gelatin with alcalase was lower than that without enzyme treatment with higher protein content. The lowest fat content was noted in AG-1 (0.50%), with protein that was not different for all enzyme concentrations (69.65-70.21%). Gelatin with neutrase had lower ash content than that without neutrase (1.61-1.90%), with the highest protein content in NG-3 (70.89%). The pH of gelatin with alcalase and neutrase was 6.19-6.92 lower than that without enzymes. Melting points, gel strength, and water holding capacity (WHC) of gelatin with the highest alcalase levels on AG-1 and AG-2 ranged from 28.33 to 28.47°C, 67.41 to 68.14 g bloom, and 324.00 to 334.67%, respectively, with viscosity that did not differ, while the highest foam expansion (FE) and foam stability (FS) were noted in AG-1, which were 71.67% and 52.67%, respectively. The highest oil holding capacity (OHC) was found in AG-2 (283%). FS and OHC of gelatins with the highest neutrase levels in NG-2 were 30.00% and 265.33%, respectively, while gel strength, viscosity, FE, and WHC of gelatins with the highest neutrase levels did not differ with those without enzymes at all enzyme concentrations. B chain was degraded in all gelatins, and high-intensity a-chains in gelatin with alcalase and peptide fraction were formed in gelatin with neutrase. Extraction with enzymes showed loss of the triple helix as demonstrated by Fourier transform infrared spectroscopy.

Conclusion:

Based on the obtained results, the Kacang goat bone was the potential raw source for gelatin production. Enzymatic extraction can increase the quality of gelatin, especially the alcalase (0.02-0.04 U/g bone) method. This can be used to achieve the preferable quality of gelatin with a higher yield.

A novel extraction approach and unique physicochemical properties of gelatin from the swim bladder of sturgeon

BACKGROUND

Gelatin is traditionally produced from mammals and widely applied in the food industry. The production is tedious, time-consuming and environment-unfriendly, while the application is restricted because of zoonosis risk and religious sentiment.

RESULTS

Gelatin was extracted by hot water from sturgeon swim bladder after defatting with alcohol and hexane. The yield reached to 94.15% under the optimized conditions of 50 °C, 30 min and 10 mL g^-1 . Its amino acid and subunit profiles were similar to type I collagen. Compared to commercial porcine, bovine and piscine gelatins, it exhibited higher whiteness (3.38), emulsion activity (171.76 m² g^-1 ), gel strength (853.23 g), water-holding capacity (92.37%) and viscoelasticity (0.03). But the transmittance (40.56% at 450 nm and 59.07% at 620 nm), emulsion stability (30.09 min), foam expansion (203.00) and stability (26.92), gelling (16.88 °C) and melting temperature (21.80 °C) were lower. While the pH (6.87) and viscosity (28.60 mPa s) were moderate. Moreover, it made better hydrogels and nanofibers.

CONCLUSION

Gelatin was extracted from sturgeon swim bladder using a clean and efficient approach, and exhibited unique properties and great potential for the food industry. © 2020 Society of Chemical Industry.

Chicken gelatin modification by caffeic acid: A response surface methodology investigation

Chemical modifications of gelatin from mechanically separated chicken meat (MSM) residue were practiced using caffeic acid as a cross-linker. The effects of oxidation period (OP), cross-linking temperature (CT), and caffeic acid (CA) concentration were investigated. Experiments were performed using Response Surface Methodology (RSM). The effects of 16 different cross-linking modifications on the physicochemical properties of chicken gelatin gels were investigated. Maximum gel strength was determined at 12.5 min OP, 50 °C CT and 2.5% CA concentration and this was 63% higher than the control (uncross-linked chicken gelatin). Temperature has an increasing effect on the degree of cross-linking value up to a certain degree. The highest degree of cross-linking was observed at between 50° and 55 °C. The color characteristics of gels were affected by cross-linking having more brown color. Overall this study demonstrated that caffeic acid has a potential to be an efficient natural cross-linking factor increasing the mechanical properties of chicken gelatin thermo-irreversibly.

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.

Thermal stability of prepared chicken feet gelatine gel in comparison with commercial gelatines

Gelatine is, due to its functional properties, currently widely used not only in the food industry (in the production of confectionery, dairy products, canned food) but also in pharmacy (soft and hard capsules) and cosmetics (creams, lotions) where it applies its ability to form thermoreversible gel stronger than most other gelling agents. What is more, it provides further excellent properties including emulsifying, foaming, stabilizing, film-forming, water and fat binding, texturizing, thickening, and adhesive attributes which makes it a very important hydrocolloid. Gelatine is obtained from the raw material of animal tissues containing collagen, usually mammalian skin or bones. For religious reasons in some countries, pork or bovine gelatine must be replaced by an alternative form, such as poultry or fish gelatine. The quality of gelatine is assessed mostly by the strength of gelatine gel which strongly depends on ambient temperature or humidity. Extraction conditions may also significantly affect the quality of gelatine. This study examined possible changes in the strength of gelatine gels prepared from laboratory-produced chicken feet gelatine and compared them with commercially available pork and beef gelatines at temperatures of 23, 29, and 35 °C at 60 and 80% humidity. While at 23 °C thermal stability of prepared chicken gelatine was monitored higher than in commercial gelatines, experiments at 29 and 35 °C provided equivalent results for chicken and commercial gelatines. Therefore, prepared chicken gelatine offers a significant potential to become an alternative to traditional gelatines. The information about gelatine gels thermal stability is of great importance for applications not only in the food; but also in the pharmaceutical industry.

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.

Evaluation of Pork Myofibrillar Protein Gel with Pork Skin Gelatin on Rheological Properties at Different Salt Concentrations

This study was performed to evaluate the physicochemical properties of myofibrillar protein (MP) gels containing pork skin gelatin at different salt concentrations. MP gels were prepared to the different salt levels (0.15, 0.30, and 0.45 M) with or without 1.0% of pork skin gelatin. Cooking yield (CY), gel strength, shear stress were measured to determine the physical properties, and SDS-polyacrylamide gel electrophoresis, scanning electron microscopy, fourier transform infrared spectroscopy, sulfhydryl group and protein surface hydrophobicity was performed to figure out the structural changes among the proteins. The addition of gelatin into MP increased CYs and shear stress. MP at 0.45 M salt level had the highest CY and shear stress, as compared to MPs at lower salt concentrations. As the salt concentration of MP gels increased, the microstructure became the compact and wet structures, and decreased the amount of α-helix/unordered structures and β-sheet. MP with gelatin showed a decreased amount of α-helix/unordered structures and β-sheet compared to MP without gelatin. The addition of gelatin to MP did not affect the sulfhydryl group, but the sulfhydryl group decreased as increased salt levels. MP mixtures containing gelatin showed a higher hydrophobicity value than those without gelatin, regardless of salt concentration. Based on these results, the addition of gelatin increased viscosity of raw meat batter and CY of MP gels for the application to low salt meat products.

Extraction and physicochemical characterization of broiler (Gallus gallus domesticus) skin gelatin compared to commercial bovine gelatin

Gelatin was extracted from broiler (Gallus gallus domesticus) skins and analyzed to compare its physicochemical properties with those of commercial bovine gelatin. The average yield of broiler skin gelatin was 6.5% on a wet weight basis. Broiler skin gelatin had more α1-and α2-chains than β-chain and contained high molecular weight (γ-chain) polymers. Glycine was the dominant amino acid in broiler skin gelatin (20.26%), followed by proline (Pro) (15.12%) then hydroxyproline (Hyp) (11.36%). Compared to commercial bovine gelatin, broiler skin gelatin had less total imino acids (Pro and Hyp) but a higher (33.65 vs. 31.38°C) melting temperature (P < 0.01). The differences in physical properties between the broiler and commercial bovine gelatins appeared to be associated with differences in their amino acid composition and molecular weight distribution. The sensory evaluation results revealed that broiler skin gelatin could be a potential alternative to commercial bovine gelatin, useful in various food products.

Gelation kinetics and characterization of enzymatically enhanced fish scale gelatin-pectin coacervate

BACKGROUND

Protein-polysaccharide complex coacervations have been considered extensively for the development of functional foods. The main problem of the complex coacervates is that they are highly unstable under different conditions and that cross-linking is necessary to stabilize them. In this study, the effects of pectin at different concentrations on the gel and structural properties of fish scale gelatin (FSG)-high methoxyl citrus pectin (HMP) coacervate enhanced by microbial transglutaminase (MTGase) were studied.

RESULTS

The gelation rates and gel strength of the MTGase-enhanced FSG-HMP coacervate gels decreased with increasing HMP concentration. However, the enhanced coacervate gels exhibited better thermal behavior and mechanical properties compared with the original gels. Also, TG-P₈ exhibited the highest melting point (27.15 ± 0.12 °C), gelation point (15.65 ± 0.01 °C) and stress (15.36 ± 0.48 kPa) as HMP was 8 g kg^-1 . Particle size distribution, fluorescence emission and UV absorbance spectra indicated that MTGase and HMP could make FSG form large aggregates. Moreover, confocal laser scanning microscopy of treated coacervate gels showed a continuous protein phase at low HMP concentrations.

CONCLUSION

FSG and HMP could form soluble coacervate, and MTGase could improve the thermal and mechanical properties of coacervate gels. © 2017 Society of Chemical Industry.

Comparison of rheological behaviors and nanostructure of bighead carp scales gelatin modified by different modification methods

In this study, microbial transglutaminase (MTGase) and pectin were compared to modify bighead carp (Hypophthalmichthys nobilis) scale gelatin. The functional properties of modified fish scales gelatin (FSG) were largely improved, including melting temperature and rheological behavior. While, modification methods decreased the triple-helix content and destroyed the single left-hand helix chain of modified FSG as investigated by X-ray diffraction. MTGase could induce the denser and finer gels network, but had none significant effect on nanostructural properties of fish gelatin. Pectin inserted itself into the fish gelatin gels network and caused aggregations, forming crystalline peaks and various nanostructures. In particular, compared with pectin modified FSG, MTGase produced FSG with lower storage modulus and apparent viscosity, but higher gel points and melting points.

Extraction and characterization of gelatin from the feet of Pekin duck (Anas platyrhynchos domestica) as affected by acid, alkaline, and enzyme pretreatment

The effects of different pretreatments on yield and composition of extraction, physicochemical, and rheological properties of duck feet gelatin (DFG) were investigated. Gelatins were extracted from the whole feet of Pekin duck with an average yield of 4.09%, 3.65%, and 5.75% for acidic (Ac-DFG), alkaline (Al-DFG), and enzymatic (En-DFG) pretreatment on a wet weight basis, respectively. Proteins at 81.38%, 79.41%, 82.55%, and 87.38% were the major composition for Ac-DFG, Al-DFG, En-DFG, and bovine, respectively. Amino acid analysis showed glycine as the predominant amino acid in Ac-DFG, followed by hydroxyproline, proline, and alanine for Ac-DFG, Al-DFG, and En-DFG, respectively. Rheological analysis indicated that the maximum elastic modulus (9972.25Pa) and loss modulus (4956.28Pa) for Ac-DFG gelatin were significantly higher than those of other gelatins. Extracted gelatins contained α₁ and α₂ chains as the predominant components, and enzymatic gelatin had low molecular weight peptides. Fourier transform infrared spectroscopy showed that the peak of the gelatins was mainly positioned in the amide band region (amides I, II, and III). A considerable loss of molecular-order triple helical structure was also observed after pepsin treatment. In summary, duck feet gelatin has potential to replace as mammalian gelatin in food and pharmaceutical industry.