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Gelatin viscosity

Viscosity reflects the internal friction caused by the relative motion of tiny fibrous peptide chain molecules when they are dissolved and dispersed in water. For dilute solution, because the number of molecules in the system is very small, the internal friction is almost zero, and the viscosity reflects the average molecular weight of the polypeptide chain system. Therefore, under the condition of fixed temperature and pH, the viscosity measurement of dilute solution is mainly used to determine the average molecular weight of gelatin system. In the case of concentrated solutions, the viscosity is mainly caused by the hydrodynamic interaction between the gelatin molecules. In the concentration range of concentrated gelatin solution, the main variables affecting viscosity are temperature, pH value and added salts; in addition, the average molecular weight and molecular weight distribution of gelatin also affect the viscosity of gelatin. The relationship between viscosity and concentration of commercial gelatin was determined in early studies as "viscosity is an exponential function of concentration"; subsequent studies found that the logarithm of viscosity versus concentration plot is always a curve, except that the curvature decreases with the increase of concentration. The viscosity of the concentrated gelatin solution is at its lowest value at the isoelectric point pH, while the viscosity of the solution at all pH values decreases correspondingly when the salt solution is added.

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Gel strength

When the warm gelatin aqueous solution is cooled, its viscosity gradually increases. If the concentration is large enough and the temperature is low enough, the gelatin aqueous solution will be transformed into a gel. Gelatin gel resembles a solid substance, is able to hold its shape, and has elasticity. Gelatin gels can reversibly transform back to the solution state after being heated. This is an unparalleled property of gelatin. The gelatin solution is cooled at low temperature until gelation occurs and aged at a certain low temperature for a certain period of time, and its stable gel strength value can be measured. The gel strength of gelatin is related to the molecular weight and its distribution, amino acid composition and process of gelatin, and the gel strength required by different uses of gelatin is also different. The freezing of the gelatin solution and its subsequent change in the gel network is caused by the partial reversion of the disordered gelatin molecules in the solution to the collagen structure.

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Gelatin surface activity

Polypeptide chains composed of amino acids have hydrophilic and hydrophobic regions, so that gelatin has appropriate surface activity as well as some surfactants. Studies have shown that the surface tension of gelatin solution is related to its concentration, temperature, pH and other factors. When the concentration of gelatin solution is 1% or less, the temperature is 10~45 ℃, and the solution is formed for less than 1 hour, it is found that the surface tension is the maximum between pH = 2~3, and the minimum surface tension occurs at the isoelectric point. The study also points out that the surface tension decreases linearly with temperature below 30 ℃, decreases more sharply between 30 and 40 ℃, and decreases further with the increasing temperature above 40 ℃, and its decline rate is greater than that of pure water. Where aging occurs, the surface tension will generally decrease with time.

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Physicochemical properties of gelatin

Gelatin is the product of collagen denaturation, belongs to the protein macromolecule category, it has similar characteristics with protein macromolecules, but because of the particularity of the molecular structure, determines its physical and chemical properties and unique

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Application of Gelatin

Gelatin is commonly used as a gelling agent for foods, drugs, or cosmetics. Gelatin is an irreversibly hydrolyzed form of collagen and is classified as a food product. It is commonly used in fudge as well as other products such as marshmallows, ice cream and yogurt. Gelatin is generally used in food in the form of tablets, granules or powder, and sometimes it needs to be pre-dissolved in water when used. Gelatin its E code for food additives is E441.

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Physiological function of gelatin

Gelatin is made by steaming collagen, a protein found in animal skin, hooves, connective tissue and bones. The cooking process breaks the bonds between proteins, resulting in smaller, more bioavailable structural blocks that your body can easily absorb.