Gelatin

Product Overview

Gelatin is a large molecule hydrophilic colloid, a product of partial hydrolysis of collagen. Depending on its performance and use, it can be categorized into photographic gelatin, edible gelatin, and industrial gelatin. The quality requirements for gelatin vary according to its application. When used as an adhesive, bonding strength is the primary requirement. For applications in photography, food, and medicine, the purity of the product is emphasized.

Collagen molecules consist of three intertwined polypeptide chains forming a helix. Through processing, the helix is denatured and broken down into single polypeptide chains (α-chains), α-components formed by two α-chains, γ-components formed by three α-chains, and molecular chain fragments smaller than α-components or larger than γ-components. Therefore, gelatin is a polydisperse system with a certain molecular weight distribution, which varies with processing conditions and affects its physical and chemical properties.

Production Process

1. Gelatin is the product of moderate hydrolysis and thermal denaturation of collagen. The main raw materials for gelatin production include animal skins, bones, and leather industry by-products. Most commonly available gelatin in the market is prepared from cowhide, cow bones, or pigskin. In recent years, due to the emergence of mad cow disease and foot-and-mouth disease, many gelatin manufacturers have turned to producing gelatin from fish skin, fish scales, and chicken skin. Currently, the main production methods for gelatin include the alkaline method, acid method, and enzymatic method. The alkaline and acid methods are traditional production methods, with a longer production cycle of about 15 days, and the waste liquid discharged causes significant environmental pollution. Due to the lower production cost and higher safety of enzymatically produced gelatin, it has gradually replaced acid and alkaline-produced gelatin in the pharmaceutical and food fields.

1. Acid Method Production
2. The production of gelatin mainly consists of three processes: collection, preservation, and pretreatment of raw materials such as skins and bones, which are the preliminary steps in gelatin technology development. The degradation of collagen, or gelatin extraction, is the second process and the key part affecting yield. The final process includes filtration, evaporation, sterilization, and drying. The difference between the acid and alkaline methods lies in the chemical treatment methods used during the preliminary processing and gelatin extraction stages. The acid method typically uses hydrochloric acid, sulfuric acid, phosphoric acid, lactic acid, citric acid, acetic acid, or a combination of these acids for raw material swelling and further breaking of molecular cross-links and bonds with a weak or strong acid to dissolve polypeptides in acidic aqueous solution, a process also known as gelatin extraction.

Alkaline Method Production

In the alkaline method of gelatin preparation, collagen-containing raw materials are first pretreated by soaking in lime, washing, and degreasing. After pretreatment, the fat content is low, and the main component is collagen protein, which is gradually degraded into a mixture of polypeptides of varying molecular weights under the conditions of lime or sodium hydroxide and certain temperatures. After a series of treatments, including concentration, dehumidification, and drying, a solid powder is obtained. In terms of product yield, properties, and purity, the alkaline method can produce high-quality gelatin. Currently, more than 80% of domestic gelatin is alkaline gelatin. The lime and caustic soda methods are commonly used in the alkaline production of gelatin. The lime method for pigskin gelatin production typically involves raw material sorting, lime water pre-soaking, hydraulic degreasing, lime water soaking, washing and neutralizing, boiling gelatin, concentration, bleaching, and gelatinization.

Enzymatic Method Production

Enzyme-catalyzed collagen degradation to prepare gelatin greatly shortens the production cycle compared to the traditional alkaline method, which has been a focus of research for foreign gelatin scientists. Research on enzymatic gelatin production began in 1962 and has a history of over 50 years. It is well known that gelatin can be produced by degrading collagen with enzymes, but the resulting gelatin has a broader molecular weight distribution, with a higher content of high molecular weight components, making process control more difficult. These defects affect the quality of gelatin.

The enzymatic gelatin preparation method involves treating crushed bone or skin collagen with an enzyme solution, then stirring in an acidic solution to obtain a collagen solution, followed by neutralization to the isoelectric point of collagen or salt precipitation to obtain collagen fiber precipitate. After separating the precipitate and heating, gelatin is obtained. Another method is enzyme-based liming, where the enzyme solution replaces the lime milk used in the traditional alkaline method to treat collagen bone or skin, followed by completing the remaining steps according to the traditional method. This process is more suitable for bone gelatin preparation. The general enzymatic gelatin production process includes skin material pretreatment, enzymatic hydrolysis, enzyme inactivation, solubilization, separation, purification, and the final product.

Functions and Benefits

Gelling agent, stabilizer, emulsifier, thickener

Applications:

Candy Additive:

It's reported that over 60% of the world’s gelatin is used in the food and candy industry. In candy production, gelatin is used to make caramels, marshmallows, gummy candies, and more. Gelatin has water-absorbing and structure-forming properties. Once dissolved in water, gelatin particles attract each other and intertwine, forming a layered network structure that solidifies as the temperature drops. This allows the sugar and water to fill the gel's gaps completely, enabling soft candies to maintain their shape even under significant load. Generally, the amount of gelatin used in candy ranges from 5% to 10%. In crystal gummy candies, a 6% gelatin concentration is optimal. Gummy candies typically contain 6.7% gelatin, while nougat contains between 0.6% to 3% or more. For thick syrup-based candy, the gelatin content ranges from 1.5% to 9%. Ingredients like lozenges or date candies require 2% to 7% gelatin. Compared to starch or agar, gelatin provides greater elasticity, toughness, and transparency in candy production, especially in producing elastic, full-shaped gummy candies and caramels, where high-quality gelatin with strong gelling strength is needed.

Frozen Food Improver:

In frozen foods, gelatin can be used as a gelling agent. Gelatin gels have a low melting point and easily dissolve in warm water, creating a melt-in-the-mouth sensation. It’s often used in the production of table jellies and grain jellies. Gelatin can also be used in making jellies, as it does not crystallize in warm syrup that hasn’t yet melted, and the warm jelly can reform after being stirred into a gel. As a stabilizer, gelatin is used in ice cream and frozen treats. Gelatin’s role in ice cream is to prevent the formation of large ice crystals, maintain a delicate texture, and slow the melting process. The ideal amount of gelatin in ice cream ranges from 0.25% to 0.6%. Any gelatin with gelling strength can produce good ice cream, but the strength must correspond to the appropriate concentration.

Meat Product Improver:

Gelatin, as a gelling agent, is added to meat products such as sausages, canned ham, veal, ham pies, canned meats, and more, to improve yield and quality. Gelatin also serves as an emulsifier in some meat products, such as emulsified meat pastes and cream soups, preserving the original characteristics of the product. In canned foods, gelatin also acts as a thickener, often added as powdered gelatin or as a concentrated gel made of one part gelatin to two parts water.

Beverage Clarifying Agent:

Gelatin can be used as a clarifying agent in the production of beer, wine, fruit wine, almond milk beverages, and more. The mechanism involves gelatin forming flocculent precipitates with tannins, which then adsorb, coagulate, and settle with the cloudy substances, which can be filtered out. In different beverages, gelatin can be used with other substances to achieve specific effects. For example, in mulberry juice production, gelatin needs to work with tannin and silica gel as clarifying agents. In almond milk beverages, gelatin can be used with sodium alginate as a composite thickener to create a beverage with unique flavor and texture. The amount of gelatin added varies depending on the beverage. In fruit juice drinks, the gelatin content ranges from 2% to 3%; in clarifying bayberry juice, a 1% gelatin solution is used. For beer clarification, a 0.5% gelatin solution is used. In wine clarification, the gelatin amount is 0.1 to 0.3 g/L. In tea beverages, gelatin can be combined with different substances to improve the quality, such as using gelatin and silica gel in black tea to prevent cloudiness from long-term storage, or mixing gelatin with polyvinylpyrrolidone in green tea production for a smoother taste in cold drinks.

Food Coating Material:

In recent years, Japan and other countries have increasingly used gelatin as a food coating. Coating food with gelatin has the following advantages: (1) It can inhibit browning when combining two different foods; (2) It prevents moisture absorption and hardening, as gelatin-coated powdered or granular sugars resist moisture absorption and clumping; (3) It adds shine to food surfaces, improving quality; (4) It prevents food spoilage and oxidation. A 10% to 15% gelatin coating is suitable for hams, cured meats, sausages, and cheeses, preventing spoilage and extending shelf life; (5) Gelatin acts as a stabilizer, preventing shrinkage and deformation of products; (6) It preserves freshness, as gelatin solutions added to sugar syrups used for soaking fruits and vegetables form a protective film on the surface, maintaining the freshness and natural flavor of the produce.

Gelatin is also used in cake production and various sugar coatings. Thanks to its stability, these coatings do not seep into the pastry even in hot weather when the liquid phase increases, and it also controls the size of sugar crystals. Gelatin can also be used to produce colorful beads in ice cream and sugar-free canned goods. In food packaging, gelatin can be synthesized into gelatin films, also known as edible packaging films or biodegradable films. These films have good tensile strength, heat sealability, and high resistance to gas, oil, and moisture, making them ideal for preserving fruits, meats, and other foods or even for direct consumption.

Adhesive for Cast-Coated Paper:

Due to the high cost of casein used in cast-coated paper production, research and factory tests have shown that hydrolyzed and bleached low-grade industrial gelatin can be used as an adhesive for cast-coated paper.

One of gelatin’s most important properties is its ability to form a reversible gel, which has significant applications in film production, fabrics, coatings, and capsules. Patents have been filed for using this gel to create molds for automotive parts. Due to its foaming properties, gelatin can be used in fire retardants, crop protection covers, coating substrates, dust suppression materials, and in the production of sound-absorbing foam cement compounds, thermal insulators, and fireproof materials. Gelatin-based leather glue, known for its adhesiveness, is more commonly used and environmentally friendly than synthetic glues and is used as a sizing agent in paper manufacturing, for producing sandpaper, and adhesive tape paper. NASA developed a powerful collagen adhesive for bonding aluminum sheets in aircraft exteriors, stronger than any riveting or bonding method. Gelatin’s emulsifying properties can be used as a protective colloid and flocculant in cosmetics and coatings, and the higher the Bloom value of gelatin, the better its emulsifying ability. Gelatin’s oil absorption properties are useful for recovering oil spills, while its water absorption properties can be applied in controlled-release pesticide systems in agriculture.

Other Applications:

Gelatin, starch, algin, and carrageenan can be used as shell materials in high-concentration capsule detergents with excellent storage stability, descaling effects, and biodegradability. Japanese research has reported that gelatin reacts with lauroyl chloride in alcoholic solutions to form peptide-lauric acid salts, which can be used as surfactants with good solubility in hard water, low odor, and good foaming properties. Another Japanese report discusses using water-insoluble N-acylated gelatin to encapsulate cosmetic pigments, preventing direct skin contact while providing moisturizing benefits.

Photographic Industry:

Gelatin's unique properties make it vital in traditional photosensitive materials, and it is also used in new photosensitive materials. Some researchers have developed inkjet printing receptor layers containing photosensitive silver halide microcrystals using gelatin. These materials include a base layer with a photosensitive layer containing silver halide on one side and an ink-absorbing layer with various hydrophilic colloids on the other. This material allows inkjet printing immediately after washing the photosensitive material and has good ink affinity at high temperatures.

With the rise of digital cameras, inkjet paper for color photo hard copies has started to be sold, where one or both sides of the paper are coated with a gelatin layer.

Cosmetic Industry:

Gelatin, collagen hydrolysates, and their derivatives are used in cosmetics for their protective, moisturizing, and cleansing properties for the skin and hair, but these additives only show significant effects when used in conjunction with specific cosmetic ingredients.

Protein complexes with sodium lauryl ether sulfate protect the eyes. Neutral and acid-soluble collagen solutions can be combined with synthetic soaps, and other detergents can prevent harmful effects (like irritation) from detergents on the skin. This is because gelatin, collagen hydrolysates, and their derivatives form micelles around the detergents, making synthetic soaps and other detergents milder. Simultaneously, they can enhance the cleansing power of detergents without reducing or only slightly reducing foam activity. Protein-containing soaps and detergents also have excellent moisturizing effects and emulsify certain oils, such as eyebrow dye oils, lipsticks, and eye creams, leaving the skin feeling soft, non-dry, and non-sticky after washing.

Protein-containing hair cosmetics can increase hair tensile strength and elasticity, making them commonly used in perming, styling, rinsing, and drying cosmetics. Proteins are often added to conditioners to reduce the damage of surfactants, alkalis, and peroxides to hair. Common hair care products include moisturizing shampoos, hair conditioners or lotions, wool-protein conditioners, protein fixatives, and more.

Paper Making

Gelatin plays an important role in the paper industry. It is used in handcrafted paper and almost all high-quality paper, especially those made from rags. It is also applied in paper made from wood pulp or rags and wood pulp paper as a sizing agent, either alone or in a gelatin-starch mixture. For handcrafted paper, a gelatin solution containing 3%–5% alum is generally used for sizing; for high-quality paper made from rags, wood pulp, or Spanish grass, the sizing solution contains 4%–8% gelatin, 3%–5% alum, and 0.1%–0.75% formaldehyde to ensure the gelatin forms a film upon drying.

After gelatin sizing, paper surfaces become smooth, durable, and less prone to staining, with a distinctive sound when handled. Gelatin-sized banknote paper can withstand frequent folding over the years. Barium-coated paper has a layer of barium oxide to give the paper a specific hue. To create paper that holds permanent prints, a mixture of gelatin, formaldehyde, glycerin, and alum is applied. Paper treated with gelatin, glycerin, and formaldehyde is dense and resistant to gas and liquid leakage. Gelatin, lithium chloride, and formaldehyde treatment produces conductive materials and transparent layered materials. Adding gelatin and guanidine resin to the pulp enhances the paper's water resistance. Gelatin is also used in the production of office paper, carbon paper, and drafting paper. In summary, gelatin is highly useful in the paper industry. For use as an adhesive in paper making, gelatin with low freeze-thaw stability and low viscosity is generally preferred, and bone gelatin may be used to ensure the adhesive penetrates the surface of the material, improving bonding effectiveness.

Packaging and Storage:

Storage Conditions: Store in a sealed, light-proof container, away from high temperatures, in a dry, cool, and well-ventilated place.

Packaging: Bulk packaging in 25 kg cardboard drums, small samples in 1 kg aluminum foil bags, or according to customer requirements.

Transportation: Via courier or logistics. Domestic courier delivery within three days, logistics within five days. Prices typically include domestic shipping costs.

Shelf Life: Two years