A preliminary investigation of the stages of adipocere formation

Adipocere is a postmortem decomposition product which forms from a body's adipose tissue. This study aimed to chemically demonstrate the process of conversion from adipose tissue to adipocere. Samples of adipocere were collected from pig cadavers that were allowed to decompose for varying intervals. Samples of soil were collected from beneath the cadavers and analyzed to determine the leaching effect of adipocere. Gas chromatography/mass spectrometry (GC/MS) was used to quantify the fatty acid composition of pig adipocere. Fourier transform infrared spectroscopy (FTIR) was used as a confirmatory test and to identify other components such as triglycerides and calcium salts of fatty acids. The study demonstrates the process of adipocere formation and the stages of formation through which the process passes using chemical techniques.     

The effect of the burial environment on adipocere formation

Adipocere is a decomposition product comprising predominantly of saturated fatty acids which results from the hydrolysis and hydrogenation of neutral fats in the body. Adipocere formation may occur in various decomposition environments but is chiefly dependent on the surrounding conditions. In a soil burial environment these conditions may include such factors as soil pH, temperature, moisture and the oxygen content within the grave site. This study was conducted to investigate the effect of these particular burial factors on the rate and extent of adipocere formation. Controlled laboratory experiments were conducted in an attempt to form adipocere from pig adipose tissue in model burial environments. Infrared spectroscopy, inductively coupled plasma-mass spectrometry, and gas chromatography-mass spectrometry were employed to determine the lipid profile and fatty acid composition of the adipocere product which formed in the burial environments. The results suggest that adipocere can form under a variety of burial conditions. Several burial factors were identified as enhancing adipocere formation whilst others clearly inhibited its formation. This study acts as a preliminary investigation into the effect of the burial environment on the resultant preservation of decomposing tissue via adipocere formation.     

Preliminary quantitative investigation of postmortem adipocere formation

The accurate determination of postmortem interval (PMI) using the formation of adipocere presents a significant challenge to forensic scientists interested in determining the time of death. Several attempts have been made to determine the time since the occurrence of death. However, up to date, this has been difficult because previous approaches have been mainly qualitative, focusing on the later stages of degradation processes. This work presents preliminary results of an experimental model of postmortem adipocere formation using liquid chromatography. Three pig cadavers were submerged in distilled water, chlorinated water, and saline water. Fresh specimens resulting from the degradation in the subcutaneous fat were obtained from the pigs at two-week intervals for a period of ten weeks, and were subjected to chromatographic analysis. By correlating the ratio of the disappearance of hydrolyzed fatty acids with the formation of hydroxystearic and oxostearic acids after death, a simple, quantitative analytical method was developed for the determination of PMI. Experimental observation of the chemistry of adipocere formation indicated that adipocere can be formed only a few hours after an incidence of death and this continues until the saturation of oleic acid degradation after several weeks. Different time courses were obtained for cadavers immersed in distilled, chlorinated, and saline water, respectively. This work has not in any way solved the time since death problem. But it may be an approach to the problem that has not been adequately explored.     

Waxing grave about adipocere: soft tissue change in an aquatic context

When postmortem environmental conditions are "just right," according to the "Goldilocks Phenomenon," soft tissues (and associated fatty acids) are converted into and preserved as adipocere. To better understand this conversion process and the development of adipocere three human cadavers were immersed in outside, water-filled pits for over 3 months to observe adipocere formation in an underwater context simulating actual field conditions. Recordings of environmental conditions showed that temperatures were between 21 degrees C and 45 degrees C, a range sufficient for the growth of Clostridium perfringens. Chemical analysis of liquid and tissue samples revealed an increase in palmitic acid and decrease in oleic acid. This study tracked the remarkable gross morphological changes that can occur in human bodies subjected to an aquatic postmortem environment. The results support the "Goldilocks Phenomenon" and substantiate previous findings that the presence of bacteria and water is crucial for adipocere to form.     

The effect of the method of burial on adipocere formation

A controlled laboratory experiment was conducted in order to investigate the effect of the method of burial (i.e. the presence of coffin and clothing) on the formation of adipocere. This study follows previous studies by the authors who have investigated the effect of physical conditions on the formation of adipocere present in a controlled burial environment. The study utilises infrared spectroscopy to provide a preliminary lipid profile of the remains following a 12 month decomposition period. Inductively coupled plasma-mass spectrometry was employed as a technique for determining the salts of fatty acids present in adipocere. Gas chromatography-mass spectrometry (GC-MS) was used as the confirmatory test for the identification and determination of the chemical composition of adipocere which formed in the controlled burial environments. The results suggest that coffins will retard the rate at which adipocere forms but that clothing enhances its formation. The results concur with previous observations on adipocere formation in burial environments.     

Adipocere Formation in Subtropical Climate of Northern India: A Retrospective Study

Adipocere formation depends upon multiple environmental factors. In comparison with temperate countries, it usually develops early in the subtropical climate. We have studied a retrospective data of 31 cases with adipocere formation at Department of Forensic Medicine at All India Institute of Medical Sciences, New Delhi. Most of the cases were recovered during the month of May to October from closed rooms at home, open grounds, open forest areas, various water sources, and riverbanks. The time duration of recovery from the time of death was from 12 h to 7 days 12 h. In 10 cases, adipocere formation was seen within 2 days, and in four male cases among them, the adipocere formed within a day. Most of the bodies showing adipocere formation within 2 days were recovered from land. These facts showed that subtropical climate having hot and humid weather promotes early adipocere formation compared to temperate climate.     

Adipocere: what is known after over two centuries of research

This paper reviews over two centuries of research focusing on various issues relating to adipocere. Adipocere is a crumbly, soap-like postmortem product that forms from soft tissue in a variety of environments. The timing of the formation and degradation of adipocere depends largely on the environmental circumstances. Once formed, adipocere can persist for hundreds of years, acting as a preservative. In this way, some define it as a process of mummification. This type of persistence can be useful in a forensic context as it can preserve evidence. Sustained interest in adipocere prompted many investigations into the composition and conditions of formation. More recent investigations, aided by technological advances, build upon the knowledge gained from prior studies as well as delve into the chemical composition of adipocere. This in turn provides new information on detection and documentation of constituent substances.     

The effect of soil type on adipocere formation

Adipocere refers to a postmortem product which forms from body fat in the later stages of decomposition. Factors present in the surrounding decomposition environment will influence adipocere formation and may accelerate or retard the process of conversion. One such factor important in burial environments is the type of grave soil in which the burial has taken place. This study was conducted to investigate the influence of various soil types on the formation of adipocere in grave soils. X-ray diffraction and particle size analysis were used to characterise the soils which were essentially chosen on the basis of grain size. Infrared spectroscopy, inductively coupled plasma-mass spectrometry, and gas chromatography-mass spectrometry were used to investigate the lipid profile and chemical composition of adipocere developed from decomposing tissue. The results suggest that adipocere is able to form in various soil types and that particular soil environments may accelerate its formation.     

The Initial Changes of Fat Deposits During the Decomposition of Human and Pig Remains

Abstract:  The early stages of adipocere formation in both pig and human adipose tissue in aqueous environments have been investigated. The aims were to determine the short-term changes occurring to fat deposits during decomposition and to ascertain the suitability of pigs as models for human decomposition. Subcutaneous adipose tissue from both species after immersion in distilled water for up to six months was compared using Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry and inductively coupled plasma-mass spectrometry. Changes associated with decomposition were observed, but no adipocere was formed during the initial month of decomposition for either tissue type. Early-stage adipocere formation in pig samples during later months was detected. The variable time courses for adipose tissue decomposition were attributed to differences in the distribution of total fatty acids between species. Variations in the amount of sodium, potassium, calcium, and magnesium were also detected between species. The study shows that differences in total fatty acid composition between species need to be considered when interpreting results from experimental decomposition studies using pigs as human body analogs.     

The effect of body coverings on the formation of adipocere in an aqueous environment

Adipocere is a postmortem decomposition product that consists of a mixture of fatty acids. The rate of formation of adipocere from pig adipose tissue in an aqueous environment has been monitored. The effect of various clothing and carpet material types on the process was investigated. The fatty acid composition of the adipocere was determined at regular intervals using gas chromatography-mass spectrometry. Examination of the changes to fatty acid concentrations allowed the degree of adipocere formation in the different environments to be estimated. The study demonstrated that the rate at which adipocere forms is particularly accelerated by the presence of coverings produced from natural materials. Elemental analysis by inductively coupled plasma-mass spectrometry revealed, for the most part, little change to the cations present in the adipocere formed. However, an increase in Ca concentration was observed for tissue wrapped in acrylic carpet, which was associated with a CaCO(3) additive used in the carpet manufacture.     

The formation of early stage adipocere in submerged remains: a preliminary experimental study

In some circumstances, the presence of adipocere may retard decomposition and complicate postmortem interval estimation. This article explores the correlation between Accumulated Degree Days (ADD) and early stage formation of adipocere. Sixty wild rabbit (Oryctolagus cuniculus) carcasses were used in this experiment; a control group (N = 30) deposited directly on the ground surface and an experimental group (N = 30) completely submersed in water in individual buckets. Data (water and inner body temperature, pH, and total body score) were collected every 100 ADD. Results indicated that early stage adipocere is correlated to ADD and that its formation on submersed remains is more likely to occur after 630 ADD. Skin sloughing promoted the formation of adipocere. No adipocere was formed on any of the control group rabbits. This study also highlights the fact that multiple factors influence adipocere formation and it is suggested that further research needs to be conducted into this area.     

Arid Climate Adipocere—The Importance of Microenvironment

Skeletal remains were retrieved from a cave in an arid desert environment. The submitted material consisted of dried grass, soil, and malodorous skeletal remains wrapped in leather. After examination, it was revealed that the smell had not been due to recent decomposition but to adipocere. The cause of death was listed as “undetermined” and a suggested date of death as “unknown.” Although adipocere usually requires a damp environment or submersion in water to develop, this case provides further evidence for the rare possibility of adipocere formation in an otherwise very dry environment. Wrapping of the body in leather material had produced an impermeable barrier which had sequestrated and preserved bodily fluids allowing anaerobic decay with fat hydrolysis and adipocere formation. Microenvironments may have potentially significant and quite idiosyncratic effects on decompositional processes which may initially confuse investigations.     

Evidence of adipocere in a burial pit from the foot and mouth epidemic of 1967 using gas chromatography-mass spectrometry

Gas-chromatography-mass spectrometry was used to characterise the fatty acids from soils and associated tissues excavated from a 1967 Foot and Mouth burial pit. Subcutaneous fats were mainly comprised of 55-75% palmitic acid, 17-22% stearic acid and 3-16% oleic acid as well as 5-7% myristic acid. The distribution of fatty acids confirmed that the tissues were decayed to adipocere. The loss of oleic acid to <3% in two of the decayed fats suggested advanced stages of adipocere. However, adipocere formation was limited in a third tissue sample recovered from greater depth. Inductively coupled plasma atomic emission spectrometry of the pore waters revealed a decrease in Ca concentration and concurrent increase in Na concentrations this suggested that insoluble calcium salt had formed through displacement of sodium. The use of fatty acid profiles from soils and soil interstitial pore waters provide complementary evidence of adipocere formation in foot and mouth burial pits.     

Characterization of adipocere formation in animal species

Adipocere is a soft white substance formed postmortem from fatty tissue in a decomposing body. In this preliminary study the formation of adipocere in soil was investigated for a number of animal species. Adipocere was formed from the fatty tissue of pig, cattle, sheep and rabbit. It was found that adipocere did not form from the fatty tissue of chicken or kangaroo in the time frame investigated. The issues being considered are relevant to the forensic examination of remains whose origin is otherwise uncertain or which are, in some way, related to human remains. Infrared spectroscopy and gas chromatography-mass spectrometry were used to characterise the composition of adipocere formed in the various species after different burial durations. Adipocere was observed to form at different rates among the species, but there was no distinct evidence of the fundamental composition varying between species.     

Preservation of human tissue immersed for five years in fresh water of known temperature

Two human bodies were recovered from the waters of the Duluth, Minnesota harbor. Extensive adipocere formation resulted in remarkable preservation of gross anatomic features of internal organs. Total time of immersion could be precisely estimated at five years. Water temperature during those five years could also be accurately estimated by direct measurements taken during the year following recovery of the bodies and from information supplied by a local electric power generating company. Immersion occurred at the time of the year when water temperature was highest (70 degrees F [21 degrees C]) facilitating the rapid formation of adipocere. A proposed mechanism for formation of adipocere is described.     

The identification of adipocere in grave soils

Soil samples recovered from grave exhumations have been analysed in an attempt to identify and characterise adipocere contained in the samples. The soil samples were collected from different environments, including samples recovered from forensic grave sites. Gas chromatography-mass spectrometry (GC-MS) was employed to identify adipocere and characterise the fatty acid composition. X-ray diffraction was used to characterise the soil environments.     

Experimental adipocere formation: implications for adipocere formation on buried bone

Adipocere, or grave wax (adipo = fat, cere = wax), is a distinctive decomposition product composed primarily of fatty acids (FA) and their alkali salts. FA result from the bacterial enzymatic hydrolysis of body fats. Reactions with ammonia and alkali metals originating from body fluids and pore waters of the depositional environment produce alkali salts of FA (soap). Adipocere formation is generally associated with burial of corpses with ample adipose tissue available. No indications that adipocere can form on defleshed remains have been presented in the literature. At the termination of a long-term bone diagenesis experiment, several samples were found to possess growths of an unknown compound. Gas chromatography-mass spectrometry confirmed that the growths are adipocere. The results herein reveal that adipocere can indeed form on defleshed bones under the right conditions and that even residual adipose and lipids in defleshed bones are sufficient to produce adipocere growth on the surfaces of bone.     

Postmortem changes of human bodies on the bathyal sea floor--two cases of aircraft accidents above the open sea

Forensic taphonomy in the marine context recently received growing attention. However, only limited information is available about the fate of human bodies at greater sea depth. Following two fatal aircraft accidents (west of Namibia, south of Sicily) human remains were recovered from a depth of 540-580 m (both cases) after 3 months (Namibia)/34 days (Sicily). In the Namibia case fully skeletonized bones were lifted. In the Sicily case a complete, dressed body was found exhibiting a partially skeletonized skull, starting adipocere formation and pink teeth. The rate and mode of decomposition of human bodies in the deep sea varies considerably and is mainly influenced by the local faunal composition. Of special relevance for the understanding of both cases was the oceanographic observation that the highly efficient necrophageous lyssianassids are abundant off Namibia but are rare in the Mediterranean, emphasizing the importance of collaboration of forensic and marine scientists in such case work.     

Microbial production of hydroxy and oxo fatty acids by several microorganisms as a model of adipocere formation

Some varieties of aerobic or anaerobic microorganisms from the human stool and adipocere were separated and identified. These separated microorganisms together with other authentic ones produced 10-hydroxystearic acid from oleic acid. Some bacteria could convert oleic acid to 10-oxostearic acid as well as 10-hydroxystearic acid. These findings indicate that the microbial enzyme(s) catalyzes the hydration of oleic acid and probably the oxidation of this hydrated product. Aerobic bacteria as well as anaerobic microorganisms were found to be involved in the formation of adipocere.