Gelatin is a protein produced by partial hydrolysis of collagen extracted from the bones, connective tissues, organs, and some intestines of animals such as the domesticated cattle, and horses. The natural molecular bonds between individual collagen strands are broken down into a form that rearranges more easily. Gelatin melts when heated and solidifies when cooled again. Together with water, it forms a semi-solid colloid gel. Gelatin forms a solution of high viscosity in water, which sets to a gel on cooling, and its chemical composition is, in many respects, closely similar to that of its parent collagen. Gelatin solutions show viscoelastic flow and streaming birefringence. If gelatin is put into contact with cold water, some of the material dissolves. The solubility of the gelatin is determined by the method of manufacture. Typically, gelatin can be dispersed in a relatively concentrated acid. Such dispersions are stable for 10-15 days with little or no chemical changes and are suitable for coating purposes or for extrusion into a precipitating bath. Gelatin is also soluble in most polar solvents. Gelatin gels exist over only a small temperature range, the upper limit being the melting point of the gel, which depends on gelatin grade and concentration and the lower limit, the ice point at which ice crystallizes. The mechanical properties are very sensitive to temperature variations, previous thermal history of the gel, and time. The viscosity of the gelatin/water mixture increases with concentration and when kept cool (≈ 4 °C).
The worldwide production amount of gelatin is about 300,000 tons per year (roughly 600 million lbs.) . On a commercial scale, gelatin is made from by-products of the meat and leather industry, mainly pork skins, pork and cattle bones, or split cattle hides. Recently, by-products of the fishery industry began to be considered as raw material for gelatin production because they eliminate most of the religious obstacles surrounding gelatin consumption . Contrary to popular belief, horns and hooves are not used. The raw materials are prepared by different curing, acid, and alkali processes which are employed to extract the dried collagen hydrolysate. These processes may take up to several weeks, and differences in such processes have great effects on the properties of the final gelatin products .
Gelatin can also be prepared at home. Boiling certain cartilaginous cuts of meat or bones will result in gelatin being dissolved into the water. Depending on the concentration, the resulting broth, when cooled, will naturally form a jelly or gel. This process, for instance, may be used for the pot-au-feu dish.
While there are many processes whereby collagen can be converted to gelatin, they all have several factors in common. The intermolecular and intramolecular bonds which stabilize insoluble collagen rendering it insoluble must be broken, and the hydrogen bonds which stabilize the collagen helix must also be broken . The manufacturing processes of gelatin consists of three main stages:
Common examples of foods that contain gelatin are gelatin desserts, trifles, aspic, marshmallows, and confectioneries such as Peeps and gummy bears. Gelatin may be used as a stabilizer, thickener, or texturizer in foods such as ice cream, jams, yogurt, cream cheese, and margarine; it is used, as well, in fat-reduced foods to simulate the mouthfeel of fat and to create volume without adding calories.
Gelatin is used for the clarification of juices, such as apple juice, and of vinegar. Isinglass, from the swim bladders of fish, is still in use as a fining agent for wine and beer. Beside hartshorn jelly, from deer antlers (hence the name "hartshorn"), isinglass was one of the oldest sources of gelatin.
Although gelatin is 98-99% protein by dry weight, it has less nutritional value than many other protein sources. Gelatin is unusually high in the non-essential amino acids glycine and proline, (i.e., those produced by the human body), while lacking certain essential amino acids (i.e., those not produced by the human body). It contains no tryptophan and is deficient in isoleucine, threonine, and methionine. The approximate amino acid composition of gelatin is: glycine 21%, proline 12%, hydroxyproline 12%, glutamic acid 10%, alanine 9%, arginine 8%, aspartic acid 6%, lysine 4%, serine 4%, leucine 3%, valine 2%, phenylalanine 2%, threonine 2%, isoleucine 1%,hydroxylysine 1%, methionine and histidine <1% and tyrosine <0.5%. These values vary, especially the minor constituents, depending on the source of the raw material and processing technique.
Gelatin is one of the few foods that cause a net loss of protein if eaten exclusively. In the 1970s, several people died of malnutrition while on popular liquid protein diets.
For decades, gelatin has been touted as a good source of protein. It has also been said to strengthen nails and hair. However, there is little scientific evidence to support such an assertion, one which may be traced back to Knox's revolutionary marketing techniques of the 1890s, when it was advertised that gelatin contains protein and that lack of protein causes dry, deformed nails. In fact, the human body itself produces abundant amounts of the proteins found in gelatin. Furthermore, dry nails are usually due to a lack of moisture, not protein.
Several Russian researchers offer the following opinion regarding certain peptides found in gelatin: "gelatin peptides reinforce resistance of the stomach mucous tunic to ethanol and stress action, decreasing the ulcer area by twice.
Gelatin has also been claimed to promote general joint health. A study at Ball State University, sponsored by Nabisco (the former parent company of Knox gelatin ), found that gelatin supplementation relieved knee joint pain and stiffness in athletes. These results have not yet been replicated by other researchers.
In addition to the raw material quality, also the production process itself is an effective quality assurance measure. In the production process a comprehensive monitoring system ensures that potential risks are minimized. In USA, the Food and Drug Administration (FDA), with support from the TSE Advisory Committee, has since 1997 been monitoring the potential risk of transmitting animal diseases, especially bovine spongiform encephalopathy (BSE). This study has scientifically proven that the gelatin manufacturing process itself is an effective barrier towards the proliferation of possible BSE prions.
The tests were based on a worst case scenario where the raw material came from BSE-infected cattle. No BSE prions could be detected in the gelatin produced by several manufacturing methods. Injections of these gelatins into the brain of experimental animals gave no establishment of TSE diseases. As a result of these experiments the FDA confirmed the safety of bovine bone gelatin. Prior to FDA, the Scientific Steering Committee (SSC) of the European Union (EU) in 2003 confirmed that the risk associated with bovine bone gelatin is close to zero. In 2006 the European Food Safety Authority (EFSA) stated that the SSC opinion was confirmed, that the BSE risk of bone-derived gelatin was very small, and that there was no support for the request of excluding the skull and vertebrae of bovine origin older than 12 months from the material used in gelatin manufacturing.
All reputable gelatin manufacturers today follow the Quality Management System according to ISO 9001 to comply with all required physical, chemical, microbiological and technical production and quality standards. In this way all process steps follow international laws and customer-specific quality parameters and are guaranteed and documented. For pharmaceutical grade gelatins strict regulations from the Food and Drug Administration (FDA), the European CPMP’s regulation and European Pharmacopoeia must be fulfilled. A detailed overview of the regulatory requirements for gelatin production can be found in the Gelatine Handbook, page 99-101 .