Gelatin

Gelatin is a mixture of tasteless animal protein ( coll: protein ). The main component is denatured or hydrolyzed collagen, which is produced from the connective tissue of various animal species, especially pigs, and cattle.

Gelatin lacks the essential amino acid tryptophan, it does not apply as a full protein. In unpurified form gelatin is also known as animal glue.

• 3.1 food
• 3.2 Pharmaceutical Technology
• 3.3 Medicine
• 3.4 Technical Applications
• 3.5 Geigenbau
• 3.6 -products

Properties

Gelatin swells in water and dissolves when heated from about 50 ° C. It is a hydrocolloid, wherein the gel formed ( on cooling ) during the heating is liquid again. This gel / sol transition (see also: sol- gel process ) is thermoreversible and is also responsible for ensuring that gummy bears dissolve in the mouth ( and do not stick such as starch products). Gelatin is temperature sensitive. If heated longer period than 80 ° C, it is hydrolyzed and loses more and more its jelly strength (measured in Bloom).

Like all other proteins also has gelatin amphoteric properties. Therefore, there is a pH value at which the (positive) electric charge of the amino groups is as large as the (negative) charge on the carboxyl groups. The isoelectric point of the gelatin is of Production dependent (acid decomposition: pH 6.0-9.5, alkaline digestion: pH 4.7 to 5.6 ). At the isoelectric point of gelatin is the least soluble. This property can be utilized in determining the point.

As contained in mixtures in the food industry hydroxyproline only in gelatin in appreciable amounts (about 13%) can be estimated the amount of added gelatin well by quantitative determination of this amino acid. Is separated from the gelatin - collagen hydrolyzate is hydrolysed by enzymes and sold as a food supplement.

Production

In order to obtain the initially insoluble connective tissue ( especially) skin and bones of pigs and cattle, but also poultry and fish a pulping process (hydrolysis) is subjected, which splits the peptide bonds, resulting in the so- water-solubilized collagen can be extracted. The decomposition can be done by cooking ( preparing a bouillon in the kitchen ) or by treatment with acids and bases and subsequent extraction (industrial production). Gelatin may contain 1-2 % of inorganic substances and up to 15 % water.

Sources of raw materials

In Europe, used edible gelatin is produced about 70% of pigskin ( 5 kg pigskin yield 1 kg of gelatin ). 18% of the gelatin is made from animal bones, another 10% of hides. For the preparation of the remaining portion (2 %) of gelatin other raw materials are used.

Because of the BSE disease have been established by the European Commission guidelines for the production of gelatine in 1999.

Fish gelatin is made from the collagen found in fish skins, including order Jewish and Islamic dietary laws to comply (see Kosher and Halal ). Allergic reactions to fish are relatively common. On the other hand, there are no reports of clinical reactions to gelatin present in commercial foods. There are no adequate data from provocation studies with individuals who have an allergy to fish and have specific IgE to fish gelatine or respond positively to a skin prick test with fish collagen or fish gelatin. The EFSA assessed the 2004 data provided by the Swiss fragrance and flavor maker Givaudan inadequate. Givaudan had filed an application for approval of fish gelatin for encapsulation of flavors. On the other hand, it was said at the same time that it is not very likely that fish gelatin would trigger under the specified conditions of use, a severe allergic reaction in a majority of people with fish allergy.

Industrial manufacturing process

It describes the practice by most manufacturers process for the preparation of gelatin: The starting materials for the manufacture of gelatine are connective tissue (skins and bones, hide split ) of cattle, pigs, fish or poultry. For pretreatment, fat and inorganic components from the feedstock are roughly removed and the material crushed ( bones are not broken, degreased and freed during the maceration of calcium carbonate, calcium phosphate and calcium fluoride; these demineralized substance called osseine ). Depending on the starting material is a set of two treatment methods:

• (A ) Acid treatment: the material with less cross-linked collagen (eg from pig skin) is treated for one day with sulfuric acid or hydrochloric acid and then neutralized. After intensive washing out of the salts, the collagen is extracted.
• (B ) Alkaline treatment: the material with highly cross-linked collagen (eg, calf ) is treated for a period of several weeks to several months to form ammonia with milk of lime.

The pretreated material is now soluble in warm water ( broth) and extracted with up to 5 steps with increasing temperature. The temperature is decisive for the jelly strength (Bloom value ): the lower it is, the higher the gel strength, the extraction fractions last obtained with high temperature have the lowest Gelierkräfte. For purification, the extracts of residual fat and fibers are separated and filtered. Last calcium, sodium, remaining acid residues, and other salts are removed.

In vacuum dryers, the thin liquid gelatin solution is thickened to a honey-like consistency. The high-concentration gelatin solution is sterilized, cooled and dried, being gelled and the gelled composition can be extruded in a noodle shape to a dry band. The tape is then passed through a drying tunnel, at the end of the gelatin is dried to a water content of 10-15% and is even ground into particles of desired size. For the production of leaf gelatin is accordingly not extruded into noodle form, but a gelatin film produced serves a wide-meshed network for a dry band.

Use

Food

Gelatin is partially processed in bold products and light products such as low-fat margarine, low-fat butter and reduced-fat cheeses, as well. Gelling agent for the production of confectionery such as jelly babies, wine gums, soft caramels, marshmallows, foam waffles, licorice or chocolate kisses Furthermore, they can be used in baked goods ( glaze ), dairy products (such as quark, kefir and yogurt) and desserts (such as royal jelly ( vulgo jello ), Mädchenröte ), in meat, fish and sausages such as jellied meat and aspic mints and Christmas sweets, but are also used as fining agent in beverages such as wine, cider, vinegar, and all non- naturally cloudy juices, as well as in some countries in the beer used. For the removal of suspended solids and to reduce Gerbstoffanteils in winemaking is fish gelatin as a substitute of lysozyme and casein particularly since the advent of BSE, and because of Jewish dietary laws for use.

As a means for the encapsulation of vitamin supplements ( for example, in foods or effervescent tablets ) may be used gelatin. The vitamins are water soluble and thus included dissolve on contact with liquid.

Pharmaceutical Technology

Gelatin is used in the manufacture of hard and soft capsules. In such gelatin capsules of the medicinal substance, optionally processed with required excipients, filled. Gelatin can also be used as a thickener for increasing the viscosity of liquid drug formulations. Of the many types of gelatin only gelatin A virtually ( by acid digestion won ) or B gelatin used (obtained by alkaline digestion ). In medical gelatin is used, among other things, for coating implants such as vascular prostheses.

Bovine gelatin as a stabilizer in the form of polygeline is or has been included in several vaccines, as in those against TBE, Japan encephalitis, rabies, varicella and MMR vaccine. Although allergic reactions to vaccines with a frequency of about 1 Response to 500,000 doses of vaccine are rare, plays the allergy to gelatin (in combination with thimerosal ) as an allergic reaction of the immediate type ( up to anaphylaxis ) play an important role and applies to about half all related complications responsible, so that it is now increasingly removed from vaccines.

Medicine

In medicine, gelatin is used as a drug for the treatment of volume deficiency shock.

Technical Applications

Gelatin is included on the usual photographic film and photographic paper, in some photographic precious printing process, it represents the carrier of the pigment or chemicals layer dar. Many photo printing paper for inkjet printing have a gelatin coating and are therefore often of manufacturers classic photo papers produced.

In the make-up studio in film and theater or even in rescue exercises colored gelatin is used to realistic view of the wound. The institution, how do you get to see them, for example in hospital series are also often made ​​of gelatin. In addition, it is used in the sport of paintball as a shell for biodegradable ammunition. For the determination of income channels and penetration of a projectile ballistic gelatin is used.

Violin Making

Gelatin is used as a primer given in violin after heating in a water bath directly on the wood to ensure a uniform tint of the wood during the subsequent pickling.

By-products

In the gelatin production occur in addition to the gelatin, by-products, which are further used: meat and bone meal (for example, as animal feed or fertilizer ), bone grease ( for example for the production of soap ) and calcium carbonate (for example, for the manufacture of toothpaste ). Also, metals, adhesives and particularly resistant paper can be produced with the aid of gelatin.

Alternatives

Animal diseases such as BSE have led in the past to the fact that some consumers avoid gelatin (especially for food ). In addition, gelatin is not vegetarian.

The results of the replacement methods vary greatly in their comparability with gelatin products.

Herbal thickeners and gelling agents are mostly polysaccharides, eg, isolated from different algae alginates, carrageenans and agar - agar, pectin from fruits also continue arabic, gum, starch of different origin, guar gum, xanthan gum and locust bean gum.

Alternative methods for clarifying liquids working with clay, tannin, kieselguhr or asbestos. Instead of gelatin but also casein ( from milk ), chitin ( from the fishing - waste production and Biotechnology ) and isinglass ( swim bladder of a sturgeon ) are used here. When gelatin is used as an aid in the manufacture, it does not have to be declared as an ingredient. Their use can be used in these cases, if at all, only be clarified by direct product inquiries to the manufacturer. With products of the pharmaceutical industry and other industries may be used in part to gelatin-free products.