Physical Properties Of Gelatin Research Articles

Effect of wet- and dry-salting with various salt concentrations on pork skin for extraction of gelatin

Gelatin was extracted from pork skin by applying both wet- and dry-salting, and its physical properties were evaluated. The salting-out effect was identified in the dry-salted pork skin groups using 9% and 12% salt. Protein degradation, overall extraction yield, emulsifying activity index, and gel strength of the wet-salted groups tended to increase with increasing saline solution concentration; however, the trend was opposite in the case of dry-salted groups. In contrast, the fat absorption capacity and emulsifying stability index of the gelatin samples showed opposite tendencies. The protein content of gelatin in all salted groups was significantly lower than that of the control group (p < 0.05). The pH of the wet- and dry-salted samples was lower than that of the control sample. The viscosity of gelatin in all salted groups was higher than that of the control group, and the dry-salted groups had higher viscosity than the wet-salted groups, except the wet-salted group with 12% saline solution. Overall, our findings verified that for gelatin extraction from pork skin, both wet- and dry-salting can improve the extraction yield and several physical properties of the gelatin. • Salting-in effect occurred when wet- and dry-salting for extraction of gelatin. • Confirmed that salting-in effect improved gelatin extraction from pork skin. • Physical properties of gelatin were improved when applicated wet- and dry-salting. • Physical properties of gelatin affect negatively when excessive salt addition levels.

Structure and physical properties of gelatin from bovine bone collagen influenced by acid pretreatment and pepsin

Effects of different acids and pepsin on the properties of gelatins extracted from bovine bone collagen were investigated. Pretreatment of bovine bone by different acids (hydrochloric acid, acetic acid, and citric acid) with and without pepsin was performed at 70 °C for 7 h to extract gelatin. Under the different acid treatments, the yield of gelatin was significantly different (hydrochloric acid, 4.76%; acetic acid, 4.26%; citric acid, 6.00%). Compared to no pepsin incubation group, bovine bone collagen treated with pepsin presented a higher yield (P < 0.05). Scanning electron microscopy analysis showed that citric acid disrupted more of the collagen structure compared with acetic acid and hydrochloric acid. Raman spectra revealed that all extracted gelatins had the similar secondary structure. Rheological analysis indicated that gelatin extracted with citric acid exhibited the highest maximum elastic modulus, gelling and melting temperature. Overall, the gelatin yield was affected by the type of pretreatment acid and more optimal gelatin extraction and gel properties were obtained when citric acid was used for extraction. Collagen pretreated with acid and pepsin was more efficiently extracted for gelatin compared to treatment without pepsin.

Extracellular Matrix Protein Coating of Processed Fish Scales Improves Human Corneal Endothelial Cell Adhesion and Proliferation.

PurposeCorneal transplantation can treat corneal endothelial diseases. Implanting cultivated human corneal endothelial cells (HCECs) via a cell carrier has clinical value as an alternative therapeutic strategy. This study was performed to compare the feasibility of fish scales and other biomaterials (gelatin and chitosan) as cell carriers and to investigate the effects of an extracellular matrix (ECM) protein coating to improve the cytocompatibility of fish scales.MethodsThe physical properties of gelatin, chitosan, and fish scales were compared. Immortalized HCECs (B4G12) were cultured on processed fish scales, which were coated with fibronectin, laminin, collagen IV, or FNC Coating Mix. Cell attachment and proliferation were evaluated by immunofluorescence, cell counting, and bromodeoxyuridine (BrdU) labeling assays. Immunoblots were used to examine the expression levels of integrin-linked kinase (ILK), phosphate-ILK, β-catenin, p63, and cell cycle mediators (cyclin D1 and p27Kip1).ResultsThe transparency of processed fish scales was better than that of chitosan, while the strength was higher than that of gelatin. The laminin, collagen IV, and FNC coatings facilitated B4G12 cell adhesion and proliferation, while fibronectin only facilitated cell adhesion. The laminin, collagen IV, and FNC coatings also upregulated phosphate-ILK and p63 expression. In addition, the FNC coating activated cell cycle mediators.ConclusionECM protein-coated processed fish scales can serve as a novel cell carrier to facilitate the development of HCEC transplantation.Translational RelevanceImproving the physical properties and cytocompatibility of fish scales as a cell carrier will facilitate the transplantation of HCECs into corneas for the purpose of cell therapy.

НАУЧНОЕ ОБОСНОВАНИЕ ФИЗИЧЕСКИХ СВОЙСТВ РЫБНОГО ЖЕЛАТИНА

The article presents the advantages of fish gelatin available for nutritional purposes in comparison with gelatin of mammals. Factors forming the basic physical properties of gelatin as a structure-forming agent have been identified. The analysis of melting temperature of jelly and the dynamic viscosity of fish gelatin solutions has been carried out. The melting temperature of jelly prepared from fish gelatin is 4°C lower than the minimum normalized value for mammalian gelatin, which is stipulated by the specific features of their amino acid composition. There has been found an increased value of the parameter “dynamic viscosity” (on average 30 mPa·s) in comparison with the standard value of gelatin of animal origin (on average 23 mPa·s). The molecular weight composition of fish gelatin has been determined. Gelatin has been stated not an individual substance, but a multiphase system consisting of a mixture of linear polypeptides and their aggregates. In the molecular weight distribution of fish gelatin 81.7% falls to a high molecular weight fraction with a mass higher than 100 kDa. Compared with gelatin obtained from the skins of cattle fish gelatin has higher content (by 34.7%) of molecular weight fractions (β- and γ-chains) and lower content (by 36.2%) of α-chains. The predominance of high molecular weight fractions in the composition of fish gelatin causes high rates of dynamic viscosity of its solutions. It was established that the interval of temperature transition ‘fibril-globule’ in fish gelatin is 20-25°C, and in animal gelatin - 28-30°C. It has been inferred that the thermal dependences of the rheological properties of fish and animal gelatin are different. It has been substantiated that collagens of different origin give gelatin with different properties. Physical properties of fish gelatin depend on the amino acid composition of a gelatin molecule, which is determined by the nature of collagen, and on the molecular weight distribution of α-, β-, γ-fractions of gelatin, which is determined by technological factors of gelatin production.

Effects of concentration on nanostructural images and physical properties of gelatin from channel catfish skins

Physical properties are crucial to gelatin utilization and the physical properties are determined by structure. Therefore, it is important to investigate the nanostructure and physical properties of gelatin over the full range of concentrations which are widely applied in research and industry. Nanostructure of gelatin can be investigated by atomic force microscopy (AFM). However, it is hard to obtain reliable AFM images of gelatin with high concentrations (1–6.67%). In this study, methods for imaging gelatin with high concentration were explored and developed, which mainly included six steps. Then the relationships among concentration, nanostructure and physical property of gelatin extracted from channel catfish skins ( Ictalurus punctatus) were studied. The high-resolution AFM images show fibril structure in gelatins with concentrations from 1% to 6.67%. However, in low concentrations (<1%), most nanostructures of gelatin were spherical aggregates and fibril structure only existed occasionally. Correspondingly, there were no significant differences of gel strength, texture profile and viscosity among several groups of gelatin when the concentration was lower than 1%, in contrast, these properties changed dramatically when the concentration was greater than 1%. It indicates that there must be some close relationships among concentration, nanostructure and physical property of gelatin. The illustration of nanoscale transition would help us understand the macroscale changes of physical properties.

Change in Molecular Weight Distribution and Physical Properties of Gelatin by a High Pressure Slurry Jet Pump Unit

Change in Molecular Weight Distribution and Physical Properties of Gelatin by a High Pressure Slurry Jet Pump Unit

Examination of the Influence of the Physical Properties of Gelatins on Their Gelling Characteristics

AbstractIn order to study the relationship between the gelling characteristics and the physical properties of gelatin, five gelatin samples having different properties were prepared by ultrasonic wave irradiation of the original gelatin. The setting times of these modified gelatins were measured by means of the thermal sensor method. The empirical expression (1), which was previously obtained' from the setting time (t), the concentration of the gelatin solution (C) and the cooling temperature (T) was applied to study the gelling characteristics of gelatin.t = a-(T/C) + b (1)As a result of studying the relation between the coefficients a, b and the physical properties of the gelatins, it was found that the coefficient a depended on the percentage of high molecular components in the gelatin. It was clear that the viscosity of the modified gelatins irradiated with the ultrasonic wave influenced their gelling characteristics.

The Chemical Structure and Physical Properties of Gelatin

(1955). The Chemical Structure and Physical Properties of Gelatin. The Journal of Photographic Science: Vol. 3, No. 2, pp. 60-67.

The Isoelectric Point of Gelatin in Relation to its "Minimum Physical Properties."

Most investigators are of the opinion that the physical properties of gelatin (viscosity, conductivity, osmotic pressure) are at a minimum at its isoelectric point and that its opacity is a maximum at this point. This erroneous conception is partly due to the notion that ash-free gelatin is necessarily isoelectric. Gelatin, whose high degree of purity is indicated by an exceptionally low conductivity when it is free from diffusible electrolytes is not isoelectric. Cataphoresis experiments show that purified gelatin derived from lime conditioned stock migrates to the anode in an electrical field, while gelatin from acid conditioned stock migrates toward the cathode. The former must therefore be a weak acid while the latter is a weak base. The physical properties of gelatin are at a minimum in pure gelatin and not in isoelectric gelatin, which is a salt of gelatin and more highly ionized than pure gelatin. Pure gelatin from any source should have the formula HONH3 × COOH (where × represents the main gelatin radical and the other groups are representative of its acid and basic groups) and should accordingly furnish the ions HO- NH3+ × COOH+. In the case of gelatin, which is a weak acid, the number of ionized groups furnishing H+ would be greater and in the case of gelatin which is a weak base the number of groups furnishing OH- ions would be greater, so that the 2 types of ionized gelatin may be represented by (HONH3 × COO)-H+ and HO- (NH3 × COOH)- respectively. It can be seen readily that the addition of an acid (HCl) to the type of gelatin (HONH3 × COO)- H+ will partly suppress its ionization and react with some of the OH groups of the molecule to form a chloride of gelatin ClNH3 × COOH which would dissociate to furnish the more highly ionized Cl- NH3+ × COO- H+, just as the addition of HCl to NH4OH forms the more highly ionized NH4Cl.

INFLUENCE OF THE CONCENTRATION OF ELECTROLYTES ON SOME PHYSICAL PROPERTIES OF COLLOIDS AND OF CRYSTALLOIDS

1. When a 1 per cent solution of a metal gelatinate, e.g. Na gelatinate, of pH = 8.4 is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain rate which can be measured by the rise of the level of the liquid in a manometer. When to such a solution alkali or neutral salt is added the initial rate with which water will diffuse into the solution is diminished and the more so the more alkali or salt is added. This depressing effect of the addition of alkali and neutral salt is greater when the cation of the electrolyte added is bivalent than when it is monovalent. This seems to indicate that the depressing effect is due to the cation of the electrolyte added. 2. When a neutral M/256 solution of a salt with monovalent cation (e.g. Na(2)SO(4) or K(4)Fe(CN)(6), etc.) is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain initial rate. When to such a solution alkali or neutral salt is added, the initial rate with which water will diffuse into the solution is diminished and the more so the more alkali or salt is added. The depressing effect of the addition of alkali or neutral salt is greater when the cation of the electrolyte added is bivalent than when it is monovalent. This seems to indicate that the depressing effect is due to the cation of the electrolyte added. The membranes used in these experiments were not treated with gelatin. 3. It can be shown that water diffuses through the collodion membrane in the form of positively charged particles under the conditions mentioned in (1) and (2). In the case of diffusion of water into a neutral solution of a salt with monovalent or bivalent cation the effect of the addition of electrolyte on the rate of diffusion can be explained on the basis of the influence of the ions on the electrification and the rate of diffusion of electrified particles of water. Since the influence of the addition of electrolyte seems to be the same in the case of solutions of metal gelatinate, the question arises whether this influence of the addition of electrolyte cannot also be explained in the same way, and, if this be true, the further question can be raised whether this depressing effect necessarily depends upon the colloidal character of the gelatin solution, or whether we are not dealing in both cases with the same property of matter; namely, the influence of ions on the electrification and rate of diffusion of water through a membrane. 4. It can be shown that the curve representing the influence of the concentration of electrolyte on the initial rate of diffusion of water from solvent into the solution through the membrane is similar to the curve representing the permanent osmotic pressure of the gelatin solution. The question which has been raised in (3) should then apply also to the influence of the concentration of ions upon the osmotic pressure and perhaps other physical properties of gelatin which depend in a similar way upon the concentration of electrolyte added; e.g., swelling. 5. When a 1 per cent solution of a gelatin-acid salt, e.g. gelatin chloride, of pH 3.4 is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain rate. When to such a solution acid or neutral salt is added-taking care in the latter case that the pH is not altered-the initial rate with which water will diffuse into the solution is diminished and the more so the more acid or salt is added. Water diffuses into a gelatin chloride solution through a collodion membrane in the form of negatively charged particles. 6. When we replace the gelatin-acid salt by a crystalloidal salt, which causes the water to diffuse through the collodion membrane in the form of negatively charged particles, e.g. M/512 Al(2)Cl(6), we find that the addition of acid or of neutral salt will diminish the initial rate with which water diffuses into the M/512 solution of Al(2)Cl(6), in a similar way as it does in the case of a solution of a gelatin-acid salt.

AMPHOTERIC COLLOIDS

1. When we plot the values of osmotic pressure, swelling, and viscosity of gelatin solutions as ordinates over the pH as abscissae, practically identical curves are obtained for the effect of monobasic acids (HCl, HBr, HNO(3), and acetic acid) on these properties. 2. The curves obtained for the effect of H(2)SO(4) on gelatin are much lower than those obtained for the effect of monobasic acids, the ratio of maximal osmotic pressures of a 1 per cent solution of gelatin sulfate and gelatin bromide being about 3:8. The same ratio had been found for the ratio of maximal osmotic pressures of calcium and sodium gelatinate. 3. The curves representing the influence of other dibasic and tribasic acids, viz. oxalic, tartaric, succinic, citric, and phosphoric, upon gelatin are almost identical with those representing the effect of monobasic acids. 4. The facts mentioned under (2) and (3) permit us to decide between a purely chemical and a colloidal explanation of the influence of acids on the physical properties of gelatin. In the former case we should be able to prove, first, that twice as many molecules of HBr as of H(2)SO(4) combine with a given mass of gelatin; and, second, that the same number of molecules of phosphoric, citric, oxalic, tartaric, and succinic acids as of HNO(3) or HCl combine with the same mass of gelatin. It is shown in the present paper that this is actually the case. 5. It is shown that gelatin sulfate and gelatin bromide solutions of the same pH have practically the same conductivity. This disproves the assumption of colloid chemists that the difference in the effect of bromides and sulfates on the physical properties of gelatin is due to a different ionizing and hydratating effect of the two acids upon the protein molecule.

AMPHOTERIC COLLOIDS

1. The method of removing the excess of hydrobromic acid after it has had a chance to react chemically with gelatin has permitted us to measure the amount of Br in combination with the gelatin. It is shown that the curves representing the amount of bromine bound by the gelatin are approximately parallel with the curves for the osmotic pressure, the viscosity, and swelling of the gelatin solution. This proves that the curves for osmotic pressure are an unequivocal function of the number of gelatin bromide molecules formed under the influence of the acid. The cc. of 0.01 N Br in combination with 0.25 gm, of gelatin we call the bromine number. 2. The explanation of this influence of the acid on the physical properties of gelatin is based on the fact that gelatin is an amphoteric electrolyte, which at its isoelectric point is but sparingly soluble in water, while its transformation into a salt with a univalent anion like gelatin Br makes it soluble. The curve for the bromine number thus becomes at the same time the numerical expression for the number of gelatin molecules rendered soluble, and hence the curve for osmotic pressure must of necessity be parallel to the curve for the bromine number. 3. Volumetric analysis shows that gelatin treated previously with HBr is free from Br at the isoelectric point as well as on the more alkaline side from the isoelectric point (pH >== 4.7) of gelatin. This is in harmony with the fact that gelatin (like any other amphoteric electrolyte) can dissociate on the alkaline side of its isoelectric point only as an anion. On the more acid side from the isoelectric point gelatin is found to be in combination with Br and the Br number rises with the pH. 4. When we titrate gelatin, treated previously with HBr but possessing a pH = 4,7, with NaOH we find that 25 cc. of a 1 per cent solution of isoelectric gelatin require about 5.25 to 5.5 cc. of 0.01 N NaOH for neutralization (with phenolphthalein as an indicator). This value which was found invariably is therefore a constant which we designate as "NaOH (isoelectric)." When we titrate 0.25 gm. of gelatin previously treated with HBr but possessing a pH < 4.7 more than 5.5 cc. of 0.01 N NaOH are required for neutralization. We will designate this value of NaOH as "(NaOH)(n)," where n represents the value of pH. If we designate the bromine number for the same pH as "Br(n)" then we can show that the following equation is generally true: (NaOH)(n) = NaOH (isoelectric) + Br(n). In other words, titration with NaOH of gelatin (previously treated with HBr) and being on the acid side of its isoelectric point results in the neutralization of the pure gelatin (NaOH isoelectric) with NaOH and besides in the neutralization of the HBr in combination with the gelatin. This HBr is set free as soon as through the addition of the NaOH the pH of the gelatin solution becomes equal to 4.7. 5. A comparison between the pH values and the bromine numbers found shows that over 90 per cent of the bromine or HBr found was in our experiments in combination with the gelatin.