Adipocere (Forensic Science)
The production of adipocere by a body generally requires an anaerobic surrounding (that is, one without free oxygen), a sufficient quantity of body fat (that is, adipose containing connective tissue with lipids present), and any of a variety of bacteria that take oxygen away from other compounds and thus assist in the hydrolysis of the fats. The material was first recognized and described in the seventeenth century, when Sir Thomas Browne wrote in Hydriotaphia, Urne Buriall (1658) of encountering the substance while relocating previously buried individuals from an English cemetery. The process of adipocere formation is called saponification, which literally means “soap making” (in times past, soap was made with a combination of animal fat, water, and lye, which produced a grayish-white material that was similar to adipocere in appearance and texture). Because adipose tissue, or body fat, can be either white or brown, adipocere may appear grayish-white or tan in color. It was not until the use of microscopes became widespread during the seventeenth century that scientists began to understand the chemical process of saponification.
Adipocere is an artifact of the decomposition process, and because its formation requires that lipids (fats) be present, it is more commonly seen among animal remains containing comparatively high levels of fat. Among humans, this means that adipocere is found most frequently on the bodies of women,...
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Further Reading (Forensic Science)
Gill-King, Herrell. “Chemical and Ultrastructural Aspects of Decomposition.” In Forensic Taphonomy: The Postmortem Fate of Human Remains, edited by William D. Haglund and Marcella H. Sorg. Boca Raton, Fla.: CRC Press, 1997.
O’Brien, Tyler G., and Amy C. Kuehner. “Waxing Grave About Adipocere: Soft Tissue Change in an Aquatic Context.” Journal of Forensic Sciences 52, no. 2 (2007): 294-301.
Spitz, Werner U., ed. Spitz and Fisher’s Medicolegal Investigation of Death: Guidelines for the Application of Pathology to Crime Investigation. 4th ed. Springfield, Ill.: Charles C Thomas, 2006.
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Adipocere (World of Forensic Science)
Also known as "grave wax," adipocere (from the Latin, adipo for fat and cera for wax) is a grayish-white postmortem (after death) matter caused by fat decomposition, which results from hydrolysis and hydrogenation of the lipids (fatty cells) that compose subcutaneous (under the skin) fat tissues.
Although decomposition of fatty tissues starts almost immediately after death, adipocere formation time may vary from two weeks to one or two months, on average, due to several factors, such as temperature, embalming and burial conditions, and materials surrounding the corpse. For instance, the subcutaneous adipose (fatty) tissue of corpses immersed in cold water or kept in plastic bags may undergo a uniform adipocere formation with the superficial layers of skin slipping off.
Several studies have been conducted in the last ten years to understand and determine the rate of adipocere formation under different conditions. Other studies also investigated the influence of some bacteria and chemicals, present in grave soils, in adipocere decomposition. Although this issue remains a challenging one, the purpose of such studies is to establish standard parameters for possible application in forensic analysis, such as the estimation of time elapsed since death when insect activity is not present. In forensics, adipocere is also important because preserved body remains may offer other clues associated either with the circumstances surrounding or the cause of death. The ability of adipocere to preserve a body has been well illustrated in exhumed corpses, even after a century.
Adipose cells are rich in glycerol molecules and are formed by triglycerols (or triglycerides). Bacterial activity releases enzymes that break these triglycerides into a mixture of saturated and unsaturated free fatty acids, a process known as hydrolysis. In the presence of enough water and enzymes, triglycerol hydrolysis will proceed until all molecules are reduced to free fatty acids. Unsaturated free fatty acids, such as palmitoleic and linoleic acids, react with hydrogen to form hydroxystearic, hydroxypalmitic acids and other stearic compounds, a process known as saponification, or turning into soap.
This final product of fat decomposition, or adipocere, can be stable for long periods of time due to its considerable resistance to bacterial action. This resistance allows for slower decomposition of those areas of a corpse where adipose tissues are present, such as cheeks, thighs, and buttocks. When a corpse is exposed to insects, however, adipocere probably will not be formed, as body decomposition will be much faster because of the insects' action. Animal scavenging of a dead body will also prevent adipocere formation.
SEE ALSO Decomposition; Entomology; Forensic science.