Gelatin Extraction Research Articles

Meat & bone meal extract and gelatin as renewable flocculants

Readily available proteins were tested as renewable flocculants, and their actions were compared to that of anionic PAM, a common, commercial flocculant that requires the coaddition of a calcium ion source. Two soy proteins, a whey fraction, a porcine gelatin, and a meat & bone meal (MBM) extract were used in the flocculation test. It was found that MBM extract and porcine gelatin promoted clay flocculation, and flocculation was complete by 24 h with or without the addition of calcium chloride. The other tested proteins did not promote clay flocculation, but all of the proteins were found to be adsorbed to clay. The protein adsorptions were well described by the Langmuir model, and gelatin and MBM extract had higher maximum adsorption capacities than the other proteins. Zwitterionic buffer solutions at pH 5.5, 7.0, and 10.0 were tested in the flocculation experiments. Addition of the pH 5.5 buffer caused the two soy proteins to become clay flocculants and lowered the concentration of gelatin and MBM extract necessary to promote complete flocculation by 24 h. Calcium chloride was not required for flocculation. Under optimal testing conditions, the dried weight of gelatin or MBM extract was 2.6 and 17 times higher, respectively, than the weight of anionic PAM required for complete flocculation at 24 h.

Effect of EDTA, HCl, and Citric Acid on Ca Salt Removal from Asian (Silver) Carp Scales Prior to Gelatin Extraction

Pretreatments with different chemicals at different concentrations to remove Ca compounds were studied to determine their effects on gelatin extraction from silver carp (Hypophthalmichthys molitrix) scales. During Ca removal with HCl, citric acid, and EDTA, all 3 chemicals were able to decalcify (>90%) scales; however, protein losses with EDTA were lower than with HCl and citric acid (P < 0.05), and protein losses with citric acid were lower than with HCl (P < 0.05). Ca removal with HCl yielded a solution where 4% to 5% of the protein was Hyp, with estimated gelatin losses from 0.9% to 2.5%. After 0.20 mol/L HCl was used for Ca removal, the extracted gelatin solution was 15.4% of the initial scales weight and gave a gel strength of 128 g. After using 1.2 g/L citric acid for Ca removal, the extracted gelatin solution was only 9% of the scales and the gel strength was 97 g. Using 0.20 mol/L EDTA for Ca removal gave a yield of 22% and a gel strength of 152 g. These data suggest that EDTA at 0.20 mol/L provides the best Ca removal with minimal collagen/gelatin removal (estimated gelatin loss was less than 0.013%) during the Ca removal step, and subsequently gave a high gelatin yield and gel strength. Fish gelatin has generally been extracted from fish skins and occasionally fish bones. This article focuses on removing the Ca compounds in fish scales and then producing fish gelatin with a good gel strength and yield. With further studies, this study may help the fish industry to have a new source of fish gelatin for food and pharmaceutical applications.

Extraction and Physicochemical Characterization of Greater Lizardfish (Saurida tumbil) Skin and Bone Gelatin

Type A gelatins were extracted from skins and bones of lizardfish and analyzed to determine their functional and chemical properties. Lizardfish skin gelatin had ash content of 2.2 +/- 0.3% while bone gelatin had ash content of 12.2 +/- 0.2%. Gel strength was 159.1 +/- 14 and 135 +/- 7.9 g, respectively, for skin and bone gelatins compared to 224.3 +/- 7.7 g for porcine gelatin. Gelatin from skin exhibited higher viscosity and lower setting time than bone. Skin gelatin had higher imino acid content than bone gelatin. The total imino acid content was 21.71% and 19.83% for skin and bone, respectively. Both skin and bone gelatins contained more alpha chains than beta and gamma components. Both bone and skin gelatins also contained low molecular weight (< alpha) peptides. The differences in functional properties between the skin and bone gelatins appeared to be related to differences in amino acid composition and molecular weight distribution of the gelatins.

Optimising conditions for enzymatic extraction of edible gelatin from the cattle bones using response surface methodology

SummaryThis work was initiated to optimise the factors affecting the enzymatic extraction of edible gelatin from the cattle bones using response surface methodology. A central composite rotatable design was used to evaluate the effects of the enzyme concentration, time of enzymatic treatment and extraction temperature on the yield of extraction, gel strength, apparent viscosity and absorption at 420 nm. The R2 values of regression models for all the response variables were higher than 0.9. Data analysis showed that all the process variables significantly (P &lt; 0.01) affected the gel strength and apparent viscosity of extracted gelatin, whereas the effect of extraction temperature on both yield of extraction and absorption at 420 nm was not significant (P &gt; 0.05). Graphical optimum conditions for the extraction yield, gel strength, apparent viscosity and absorption at 420 nm were determined as 6.1 ppm, 15.6 h, 70 °C; 9.1 ppm, 11.9 h, 70.3 °C; 7.86 ppm, 14.9 h, 77.5 °C and 2.8 ppm, 10 h, 60 °C, respectively. For all the response variables, the experimental values were very close to the predicted values and were not statistically different (P &lt; 0.05).

Extraction of collagen and gelatine from meat industry by-products for food and non food uses

Short tendons of slaughtered cattle, which consist of relatively pure collagen, were cleaned of lipoid substances and non-collagen proteins using a commercial enzymatic preparation. Diluted acetic acid was used to separate the acid-soluble collagen (M(N) approximately 300 kDa) for a yield of around 5%. The residue was extracted with water and the extraction conditions were derived to produce gelatine with a gel rigidity of 350-410 degrees Bloom and a yield of 55-60%. Prolonged extraction time, as well as increased extraction temperature, led to a deterioration in the gelatine quality and, therefore, the residue after aqueous extraction was processed by enzymatic hydrolysis into a collagen hydrolysate of M(N) = 500-1000 Da. Such hydrolysates can be utilized in industry as humectants in cosmetic skin-care preparations or as a secondary industrial raw material for producing surfactants of acylamino-carboxy acid type, which are known for their favourable dermatological effects. Apart from a maximum of 7% lipoid substances the proposed procedure produced no further waste so it may be regarded as a 'clean technology'.

Characterization of fish gelatin from surimi processing wastes: Thermal analysis and effect of transglutaminase on gel properties

Fish gelatin extraction from wastes of fish Herring species ( Tenualosa ilisha) was carried out by a series of pretreatment with 0.2 M Ca(OH) 2 followed by 0.1 M citric acid and final water extraction at 50 °C for 3 h. The resulting fish gelatin preparation was evaluated for its dynamic viscoelastic properties, gelling and melting temperatures and gel strength. The gelling and melting temperatures of gelatin samples (at 6.67%, w/v) were obtained from differential scanning calorimetry and rheological studies. The melting temperature of extracted fish gelatin (EFG) obtained ranged from 16.2 to 16.7 °C compared to that of commercial fish gelatin gel (CFG), from 23.7 to 25.6 °C and halal bovine gelatin (HBG), from 26.5 to 28.7 °C. On the other hand, gelling temperatures of EFG, CFG and HBG ranged from 5.1 to 5.2 °C, 11.9 to 17.46 °C, and 12.6 to 19.33 °C, respectively. EFG gave gels with a considerably lower G′ values than CFG and HBG. The bloom strength of EFG gels at 6.67% (w/v) was 69.03 g which was much lower than HBG (336.2 g) and CFG (435.9 g). Enzyme transglutaminase was added in the amounts of 0.5, 1.0, 3.0 and 5.0 mg/g gelatin to modify the gel properties of the extracted fish gelatin. The modified EFG gels obtained had higher gel strengths of 101.1 g and 90.56 g with added transglutaminase of 1.0 and 3.0 mg/g, respectively. However with addition of 5.0 mg/g enzyme the gel strength increased only up to 75.06 g. SDS-PAGE of extracted gelatin gel showed protein band intensities for α1-chains and 53 kDa but in gels added with higher concentration of transglutaminase, these protein band intensities seemed to disappear.

Processing optimization and characterization of gelatin from lizardfish (Saurida spp.) scales

Abstract Response surface methodology (RSM) with a 4-factor, 5-level central composite design (CCD) was conducted to ascertain the optimum gelatin extraction conditions from lizardfish scales. The effects of concentration of NaOH (%, X 1 ), treatment time (h, X 2 ), extraction temperature (°C, X 3 ) and extraction time (h, X 4 ) were determined. The responses included extraction yield (%), gel strength (g) at 9–10 °C and viscosity (cP) at 25 °C. The results showed the optimum conditions for the highest values of the three responses when a concentration of NaOH at 0.51%, a treatment time at 3.10 h, an extraction temperature at 78.5 °C and an extraction time at 3.02 h. The predicted responses were 10.7% extraction yield, 240 g gel strength and 5.61 cP viscosity. The experimental values were 10.6 ± 0.82% extraction yield, 252 ± 1.21 g gel strength and 7.50 ± 0.28 cP viscosity. The physicochemical properties of the lizardfish scales gelatin were characterized and the results indicated high protein and low ash content. Texture profile analysis (TPA) with compression was carried out at 30% deformation. The lizardfish scales gelatin was found to contain 20.4% imino acids (proline and hydroxyproline). Furthermore, slightly loose strands of the gel microstructure were observed using scanning electron microscopy (SEM).

DEVELOPMENT OF AN USER-FRIENDLY VIRTUAL ENVIRONMENT FOR DESIGN AND SIMULATION OF FOOD PROCESSING PLANTS: APPLICATION TO THE VALORIZATION PROCESS OF FISH SKINS TO OBTAIN GELATINES

ISHS IV International Symposium on Applications of Modelling as an Innovative Technology in the Agri-Food-Chain: Model-IT DEVELOPMENT OF AN USER-FRIENDLY VIRTUAL ENVIRONMENT FOR DESIGN AND SIMULATION OF FOOD PROCESSING PLANTS: APPLICATION TO THE VALORIZATION PROCESS OF FISH SKINS TO OBTAIN GELATINES

Physico-chemical and film forming properties of giant squid ( Dosidicus gigas) gelatin

Giant squid ( Dosidicus gigas) inner and outer tunics were subjected to hydrolysis with pepsin prior to gelatin extraction (G1 gelatin) by a mild-acid procedure. Furthermore, a second gelatin extraction (G2 gelatin) was done using the collagenous residues that remained from the first extraction. Pepsin allows the collagen solubilisation and the extraction yield to increase by yielding extracts high in α-chains. G1 exhibited good gel forming ability but G2 showed poor viscoelastic behaviour and low gel strength, in agreement with the results for the molecular weight distribution, which showed a considerably higher content of low molecular weight components. In spite of these differences, both G1 and G2 showed good filmogenic ability and similar properties were found including the absence of colour, opacity, low water vapour permeability and high puncture deformation. Nevertheless, films made from G1 had a higher puncture force than films made from G2 as a result of the different molecular weight distribution.

Extraction and electrospinning of gelatin from fish skin

Ultra-fine gelatin fibers were successfully fabricated by electrospinning from the solutions of Nile tilapia ( Oreochromis niloticus) skin-extracted gelatin in either acetic acid or formic acid aqueous solutions. The extracted gelatin contained 7.3% moisture, 89.4% protein, 0.3% lipid, and 0.4% ash contents (on the basis of wet weight), while the bloom gel strength, the shear viscosity, and the pH values were 328 g, 17.8 mPa s, and 5.0, respectively. Both the acid concentration and the concentration of the gelatin solutions strongly influenced the properties of the as-prepared solutions and the obtained gelatin fibers. At low acid concentrations (i.e., 15% (w/v) extracted gelatin solutions in 10 and 20% (v/v) acetic acid solvents or 10–60% (v/v) formic acid solvents), a combination between smooth and beaded fibers was observed. At low concentrations of the gelatin solutions in either 40% (v/v) acetic acid solvent or 80% (v/v) formic acid solvent (i.e., 5–11%, w/v), either discrete beads or beaded fibers were obtained, while, at higher concentrations (i.e., 14–29%, w/v), only smooth or a combination of smooth and beaded fibers were obtained. The average diameters of the obtained fibers, regardless of the types of the acid solvents used, ranged between 109 and 761 nm. Lastly, cross-linking of the obtained gelatin fiber mats with glutaraldehyde vapor caused slight shrinkage from their original dimension, and the cross-linked gelatin fiber mats became stiffer.

Characterization of Edible Film Fabricated with Channel Catfish (Ictalurus punctatus) Gelatin Extract Using Selected Pretreatment Methods

Farm-raised catfish are important to the economy of the southeastern states in the United States, and catfish processing produces about 55% of by-products for inexpensive sale. Therefore, the utilization of catfish by-products is of great interest to the catfish industry. The objectives of this research were to determine the optimum pretreatment method to extract catfish gelatin for edible film application, and to characterize physical, mechanical, and barrier properties of edible films fabricated with catfish skin gelatin. Catfish skins obtained from a local plant were treated with 6 selected pretreatment methods. The main extraction was performed with deionized water at 50 degrees C after pretreatment. The gelatin yield was calculated and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to characterize molecular weight (MW) profile. Color, tensile strength (TS), elongation, and water barrier property were determined to characterize the fabricated catfish gelatin films. From the results of gelatin yield, color, SDS-PAGE, as well as mechanical and barrier properties of the film, the pretreatment method with 0.25 M NaOH and 0.09 M acetic acid, followed by extraction at 50 degrees C for 3 h, was determined as the optimum extraction method. The catfish gelatin exhibited higher MW fractions than commercial mammalian gelatin. The catfish gelatin extracts possessed film-forming properties determined by TS, elongation, and water vapor permeability (WVP) comparable to those of commercial mammalian gelatin. The selected formula for catfish gelatin film was determined as 1% gelatin and 20% glycerol, resulting in greatest TS and lowest WVP.

Effect of extracting time and temperature on yield of gelatin from different fish offal

The aim of the study was to determine the optimal conditions for preparing gelatin from different kinds of fish offal: heads and backbones of Baltic cod, skins of fresh and cold-smoked salmon, and skins of salted and marinated herrings. The yield of gelatin extraction at 45 °C was 71–75% for fresh salmon skins or cod backbones, and 86%, for smoked salmon skins. When heating marinated herring skins for 15 min or salted herring skins for 45 min, about 100% of collagen was converted to gelatin. For fish skins, 45 °C and 15–60 min extraction time, depending on the kind of skins, were established as optimal conditions for preparing gelatin. The yield of gelatin extraction from the cod heads did not exceed 70%, even when a three stages process was used. In the case of backbones, 100% of collagen in the form of gelatin was isolated using this procedure. SDS-PAGE analysis showed that gelatin from fish skins was much less degraded than gelatin from pigskins.

A novel bone substitute composite composed of tricalcium phosphate, gelatin and drynaria fortunei herbal extract

The Chinese herb, Gu-Sui-Bu (GSB) (Drynaria fortunei J. Sm.) has been anecdotally reported to enhance bone healing. We had previously confirmed in vitro the efficacy and safety of GSB in bone healing, and showed that it influenced both osteoblast and osteoclast activity. For clinically useful application of these bone regenerative effects, a satisfactory delivery system for GSB is required. In this study, we determined the optimal concentration of GSB for regenerative activity in rat bone cells via MTT, alkaline phosphatase (ALP), nodule formation and TRAP assays, and designed and tested a GSB-rich bone composite material. The composite was fabricated by mixing a biodegradable GGT composite, containing genipin cross-linked gelatin and tricalcium phosphate, with the predetermined concentration of GSB (GGT-GSB). Neonatal rat calvarial culture and animal implantation were employed to evaluate and compare in vitro and in vivo the potential of GGT-GSB and GGT in regeneration of defective bone tissue. The most effective concentration of GSB was 100 mug/mL, which significantly increased osteoblast numbers, intracellular ALP levels and nodule numbers, without influencing osteoclast activity. In vitro and in vivo tests also showed that GGT-GSB accelerated bone regeneration compared to GGT. GGT-GSB thus has great potential for improved bone repair.

2‐Step Optimization of the Extraction and Subsequent Physical Properties of Channel Catfish (Ictalurus punctatus) Skin Gelatin

To optimize the extraction of gelatin from channel catfish (Ictalurus punctatus) skin, a 2-step response surface methodology involving a central composite design was adopted for the extraction process. After screening experiments, concentration of NaOH, alkaline pretreatment time, concentration of acetic acid, and extraction temperature were selected as the independent variables. In the 1st step of the optimization the dependent variables were protein yield (YP), gel strength (GS), and viscosity (V). Seven sets of optimized conditions were selected from the 1st step for the 2nd-step screen. Texture profile analysis and the 3 dependent variables from the 1st step were used as responses in the 2nd-step optimization. After the 2nd-step optimization, the most suitable conditions were 0.20 M NaOH pretreatment for 84 min, followed by a 0.115 M acetic acid extraction at 55 degrees C. The optimal values obtained from these conditions were YP = 19.2%, GS = 252 g, and V = 3.23 cP. The gelatin obtained also showed relatively good hardness, cohesiveness, springiness, and chewiness. The yield of protein and viscosity can be predicted by a quadratic and a linear model, respectively.

Optimization of gelatine extraction from grass carp ( Catenopharyngodon idella) fish skin by response surface methodology

To establish the optimum gelatine extraction conditions from grass carp fish skin, response surface methodology (RSM) was adopted in this study. The effects of concentration of HCl (%, A), pre-treatment time (h, B), extraction temperature (°C, C) and extraction time (h, D) were studied. The responses were yield (%) and gel strength ( g). A = 1.19%, B = 24 h, C = 52.61 °C and D = 5.12 h were determined as the optimum conditions while the predicted responses were 19.83% yield and 267 g gel strength. Gelling and melting points were 19.5 °C and 26.8 °C, respectively. Moreover, grass carp gelatine showed high contents of imino acids (proline and hydroxyproline) 19.47%. RSM provided a powerful tool to optimize the extraction parameters and the results may be adapted for industrial extraction of gelatine from grass carp fish skins.

Improvement of gelatin extraction from bigeye snapper skin using pepsin-aided process in combination with protease inhibitor

Gelatin extraction from bigeye snapper ( Priacanthus tayenus) skin was developed using a pepsin-aided process in combination with a protease inhibitor. The extraction efficiency was augmented by an acid-swelling process in the presence of bigeye snapper pepsin (BSP) at a level of 15 units/g alkaline treated skin at 4 °C for 48 h followed by extraction at 45 °C for 12 h with a yield of 40.3%. The complete degradation of β, α1 and α2-chains was observed in the resulting gelatin. To inhibit the proteolysis of BSP treated skin, heat treatments at different temperatures (70–90 °C) were used. The results indicated that the degradation still occurred in the resulting gelatin. When protease inhibitors were added during the gelatin extraction, the degradation of the gelatin components was markedly prevented when soybean trypsin inhibitor (SBTI) at a concentration of 0.1 μM was incorporated. However, pepstatin A could not retard the degradation, suggesting that the pepsin used was not involved in the degradation. Hydroxyproline content and bloom strength of gels from gelatin extracted from bigeye snapper skin treated with BSP and with porcine pepsin were similar, but their bloom strength was greater than the gelatin extracted from bigeye snapper skin by the conventional process, which had a substantial degradation of gelatin components. However, gelatin from bovine bone exhibited a greater bloom strength than did bigeye snapper skin gelatins, possibly due to higher hydroxyproline content.

Extraction and characterisation of gelatine from Atlantic salmon ( Salmo salar) skin

Gelatine was extracted from Atlantic salmon and Atlantic cod skin by the acid extraction process. After filtration and ion exchange treatment the extracts were colourless and free from fishy odour. In three separate experiments the average yields of gelatine from salmon and cod skins were 39.7% (±2.2%) and 44.8% (±0.2%) respectively, on a dry matter basis. Gelatine from salmon contained slightly more hydroxyproline and proline (16.6%) than cod gelatine (15.4%), whereas the content of serine was lower (4.6% versus 6.3%). Salmon gelatine expressed slightly higher gelling temperature (12 °C) than cod gelatine (10 °C), and higher initial gel strength. During storage at 10 °C, gel strengths were increased and more so with gels made from cod than from salmon gelatine. Hence, gels made from cod and salmon gelatines extracted at 56 °C achieved the same gel strength (195 g) after 7 days of storage. Gelatines extracted at a higher temperature (65 °C) gave lower gel strengths.

Extraction of muscle proteins and gelatine from cod head

A simple method to extract proteins from minced cod head by mild chemical treatment has been developed. The major part of muscle proteins was recovered by successive extraction at room temperature in dilute NaOH (pH 11) and HCl (pH 2–2.6). Gelatine was extracted at acid conditions and elevated temperatures from residual connective tissues and bones. Almost half of the total protein (47.5%) was extracted from muscle and soft tissues, whereas 12% were recovered as gelatine from soft connective tissues and bones. Functional properties of the various gelatine fractions were compared with functional properties of gelatine extracted from cod skin. Gelatine extracted from soft head connective tissues had similar molecular weight, viscosity and gel strength as gelatine from cod skin. The higher temperatures and stronger acidity necessary to extract gelatine from the head bones, resulted in more hydrolyzed gelatine with poor gelling properties, but still viscosities were only moderately lower than the viscosity of gelatine extracted from soft connective tissues.

The effect of processing conditions on the properties of gelatin from skate ( Raja Kenojei) skins

Effects of several conditions (liming concentrations, extraction solution pH, extraction temperature and extraction time) to extract gelatin from skate skin on the yield and quality properties were investigated. The optimum conditions for gelatin extraction are as follows; place skin in a lime solution of 1.5% (w/v) calcium hydroxide, extract with three volumes of water (pH 6.0) for 4 h at 50%, filter gelatin through activated carbon (250–350 mesh, 3%) and freeze-dry the colloidal suspension. The functional properties of skate skin gelatin produced by optimum extraction conditions were: gelling point 16.12 °C; melting point 19.30 °C; isoelectric point 6.45; and turbidity 6.98.

Effects of Alkaline and Acid Pretreatments on Alaska Pollock Skin Gelatin Extraction

ABSTRACT:Pretreatments with different alkalis and acids at different concentrations were used to determine their effects on gelatin extraction from Alaska pollock skin. The alkaline pretreatments with the OH concentrations lower than 0.5 mol/L removed noncollagenous proteins without significant loss of skin collagen. The acid pretreatments caused loss of collagen, even using a weak acid with a low H concentration at a low temperature. The presence of proteases might cause degradation of gelatin extract, but the pretreatments with NaOH or Ca(OH)2 at 0.1 mol/L OH concentration, or acetic acid at 0.05 mol/L H concentration could significantly decrease the degradation by proteases. The combination of an alkaline pretreatment followed by an acid pretreatment not only removed the noncollagenous proteins, but also provided the proper pH condition for extraction, during which some cross‐linkages could be further destroyed but with less breakage of polypeptide chains.