Embalming explained: Mastic verified in ancient embalming resins

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Ezine

  • Published: Dec 5, 2011
  • Author: Steve Down
  • Channels: Gas Chromatography
thumbnail image: Embalming explained: Mastic verified in ancient embalming resins


Mastic for mummies

When the ancient Egyptians embalmed their dead, they will have followed long-established procedures which have since been proven to stand the test of time. Mummies have exhibited an astonishing degree of preservation over several thousand years that allows us to study them intact today. Unfortunately for us, the recipes that were used were not recorded at the time.

The only records that have surfaced to date were written well beyond the age when mummification was at its height and are not particularly clear, so their value is limited. Physical examination by modern researchers has revealed the surgical techniques that were used, and chemical methods have helped to identify the materials used for embalming.

Plant oils and resins, wood distillates, beeswax and bitumen were all used at one time in the embalming process, as was mastic, which was confirmed in ancient embalming resins earlier this century. Mastic resin derives from the evergreen shrub Pistacia lentiscus and the key identifiers were characteristic terpene compounds. Many plants contain terpenes, and the specific compounds from mastic have been found in other plant species, but this shrub is thought to be the only plant available to the ancient Egyptians.

In order to confirm the use of mastic in mummification, a team of scientists in Germany has undertaken a comprehensive study of the terpenes present in mastic and compared them with the terpene signatures from several ancient Egyptian embalming resins. Klaus Albert and co-researchers from the University of Tubingen described their findings in the Journal of Separation Science.


Terpenes in ancient embalming resins

The team had access to six embalming resins all of which had been removed from the wrappings covering the heads of ancient mummies uncovered in a burial ground. One sample had been radiocarbon dated to 806-784 BCE and they presumed that the other five were of a similar age. Some of the resins were odourless but others had a tarry smell and their colours ranged from russet to very dark brown.

Each resin was extracted exhaustively with solvents of increasing polarity but only the results from analysing the first extract, using hexane, were reported. Portions of each extract were converted to the trimethylsilylated or methylated derivatives before analysis by GC/MS. A 5% phenyl methylpolysiloxane column was fitted to separate the various components for analysis by electron ionisation.

All samples contained a broad range of substances, the most abundant in five resins being free palmitic acid and stearic acid. In the sixth sample, the terpenoid components outweighed the total amount of fatty acids.

A comparison of the total ion chromatogram of one sample with that from an extract of a modern commercial mastic resin showed that they were very similar, strongly implying that this resin was also based on mastic. The equivalence of the major triterpenes was confirmed by comparing their mass spectra.

For further substantiation, structural studies using GC/MS and NMR spectroscopy were carried out to identify the principal triterpenes in each resin, including the modern one.


Major and minor mastic involvement

Four principal triterpenoid acids were identified both as their trimethylsilyl and methyl esters from their GC retention times and their mass spectral fragmentation patterns. They were moronic acid, oleanonic acid, masticadienonic acid and isomasticadienonic acid.

The ratios of oleanonic acid to moronic acid and of masticadienonic acid and isomasticadienonic acid in the modern mastic were 1.6 and 1.5, respectively. Similar ratios in some of the ancient mastic samples suggested that these consisted primarily of mastic.

Analysis of the surface and inner portions of one of these ancient mastics revealed that the relative abundances of the triterpenoids had decreased by about 50% but the triterpenoid ratios remained roughly the same and were not affected by weathering. So, this is a valid method for establishing the use of Pistacia resins in ancient samples.

In two other samples, these four triterpenoids were also detected but their relative abundances were markedly different to that of the modern resin. The researchers thought that this might be due to the burning of mastic as incense during the embalming process, during which thermal degradation would modify the composition.

However, the terpenoid composition of mastic after burning did not match that of these two samples, so it was proposed that the mastic resins were probably mixed with another type of plant resin. Further research into the various Pistacia species native to the Mediterranean area might throw some light on these other sources.

One positive spin-off from the incense diversion was that the triterpenoid compositions of ancient samples can be used to distinguish between the direct application of mastic during embalming and that burned as incense during the embalming process.

The identification of specific terpenes in the ancient Egyptian embalming resins, their relative proportions, and comparison with modern mastic has established criteria which can be used to confirm the use of mastic as an important embalming component.

 

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

 
The presence of mastic in ancient Egyptian embalming resins from mummies has been confirmed by scientists in Germany who were able to discount its use as incense during embalming, so that direct application to the body as a resin was the most likely source 

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