A short review of chemical analysis of foodstuffs and vibrational spectroscopy of FCR

The first analysis of archaeological food residue occurred in the 1930s, when Johannes Grüss used basic chemical tests to identify blackresidue on a ceramic vessel as overcooked milk (Craig and Collins 2002). Food residue studiesgenerally analyze lipids, proteins, DNA, and other characteristic compounds ofresidues absorbed by pottery, but also include residues on flaked andground-stone tools.  A wide range of techniques are used includingchromatography, gas spectrometry, elemental analysis, optical and resonancespectroscopy, stable isotope analysis, X-ray diffraction and immunologicaltechniques (Malainey 2010)

The first applications of FTIR and Raman spectroscopy (knowncollectively as vibrational spectroscopy) to archaeological materials was inthe 1960s, though it didn’t really take off until the 1990s when the technologyadvanced enough to allow for relatively low cost and quick analysis.  These analyses have been conducted on a widevariety of substances including perfumes, cosmetics, beeswax, resins, tar,pitches, proteins and lipids in soils, pigments, ink, and paint (Evershed 2008).  In addition to identification orcharacterization of organic and inorganic components of artifacts and residue,it can be used to identify burning in bone and sediments (byrecrystallization), and is used for provenancing various minerals.  The relative cheapness, speed of processing,and non-destructive nature make it ideal for screening before more expensiveand laborious procedures, such as collagen extraction for isotope analysis, isperformed.  Finally, it is often used inconservation and heritage management to estimate damage and deterioration.  

There has been significantly less analysis of foodstuffs byvibrational spectroscopy than other methods, but we can use the range oftechniques to inform us about the best way to approach it with vibrationalspectroscopy.  Most FTIR food analysis isfocused on identification of unknown but potential food residues. Oudemans etal. (2007), for example, were able tocharacterize a number of visible residues by their chemical structure, but wasunable match them with a specific substance.  However, he noted that that “the FTIR spectra of the charred residuesclosely resemble those of experimentally headed modern foodstuffs”.  McGovern et al., also working with potteryresidue, has successfully used FTIR in combination with HPLC UV and GC/MS toidentify tartaric acid/tartrate as a biomarker for ancient wines in France (2013), China (2004)and Egypt (2009).

Ancient botanicals and foodstuffs are also frequentlycharacterized.  Isaksson (1999) characterized macrobotanicalsfrom historical sites, and was able to show that they grouped in patternedways.  Edwards et al. (2010) was able to demonstrate thatthe supposed mistletoe berries found in an Early Bronze Age burial from the UKwere actually phosphatic urinary stones, reflecting an aspect of diet and not mortuarycustoms.  McLaren and Evans (2002) study ancient bread.  Modern experiments showed a strongcorrelation between bread and flour, indicating that their cereal databasewould act as a good reference; subsequently they were able to link different breadsup to several hundred years old with wheat and rye flours. 

There have only been a handful of residue analyses focusedon cookstone technology, and none of them utilize vibrationalspectroscopy.  Quigg et al (2001) analyzed sandstone FCR fromSouth Texas, most believed to have been used for stoneboiling, and a fewgroundstone pieces.  They used FAME (GCMSfor fatty acids) and compared the results to a database of modern, butartificially aged raw and cooked plants and animals.  They were able to match some of the stoneswith the reference collection, both plant and animal, with varying degrees ofprecision (most were either identified as “plant” or “large herbivore”, butsome were identified as specific mixtures, such as “Fish/corn/mesquite beans”).

Buonasera utilized the same technique for cookstone (2005) and groundstone (2007).  Analyzing andesitic FCR from a rock shelterin central California, she found lipids on both on- and off-site rocks (inapproximately equal concentrations). Only three rocks had significantly higher quantities, which indicatedthat few or none of the rocks were in direct contact with a source of lipids.  Further depending on which database she used,she had different results:  “Usingthe criteria developed by Marchbanks (1989), residues were identified as plant(n = 4), fish (n = 4), and land animal (n = 1). According to the criteriadeveloped by Malainey et al. (1999a–c) residues were identified as beaver(n=7), fish, or corn (n=1); two residues did not conform to any category”

In Norway, gas chromatography-mass spectrometry (GC-MS) andbulk carbon isotope analyses were used to identify the function of severalslab-lined pits.  They were used to bulkprocess marine resources, probably rendering seal, walrus and/or whale blubberfor oil (Heron et al. 2010). Relatedly,though not pertaining to food residue, FTIR has also been used to source clayballs used for stone boiling (Simms et al. 2013).

These and other experimental residue studies show that whilethe results are promising, analysts need to proceed with caution.  The most accurate studies utilize multiple methodsof chemical analysis with well-defined biomarkers and historical andpaleobotanical evidence to round it out. 

Other references of interest:

Edwards,HGM, and JM Chalmers

2005  Raman spectroscopyin archaeology and art history.

Smith,Gregory D, and Robin J.H. Clark

2004  Raman microscopy inarchaeological science. Journal of Archaeological Science 31(8):1137–1160.

Vandenabeele,Peter, Howell G. M. Edwards, and Luc Moens

2007  A decade of Ramanspectroscopy in art and archaeology. Chemical Reviews 107(3): 675–686.

Works Cited

Buonasera, Tammy

2005  Fatty acid analysis of prehistoric burned rocks: acase study from central California. Journal of Archaeological Science32(6): 957–965.

2007  Investigating the presence of ancient absorbedorganic residues in groundstone using GC–MS and other analytical techniques: aresidue study of several prehistoric milling tools from central California. Journalof Archaeological Science 34(9): 1379–1390.

Craig, OliverE., and Matthew J. Collins

2002  The removal of protein from mineral surfaces:Implications for residue analysis of archaeological materials. Journal ofarchaeological science 29(10): 1077–1082.

Edwards,Howell G. M., Janet Montgomery, Nigel D. Melton, Michael D. Hargreaves, AndrewS. Wilson, and Elizabeth a. Carter

2010  Gristhorpe Man: a Raman spectroscopic study of“mistletoe berries” in a Bronze Age log coffin burial. Journal of RamanSpectroscopy 41(11): 1533–1536.

Evershed,Richard P.

2008  Experimental approaches to the interpretation ofabsorbed organic residues in archaeological ceramics. World Archaeology40(1): 26–47.

Heron, CarlP., Gørill Nilsen, Ben Stern, Oliver E. Craig, and Camilla Nordby

2010  Application of lipid biomarker analysis toevaluate the function of “slab-lined pits” in Arctic Norway. Journal ofArchaeological Science 37(9): 2188–2197.

Isaksson,Sven

1999  Guided by Light: The swift characterisation ofancient organic matter by FTIR, IR-fingerprinting and hierarchical clusteranalysis. Laborativ arkeologi 12: 35–43.

Malainey,Mary E.

2010  A Consumer’s Guide to Archaeological Science. Ed.Mary E Malainey. Media(Chapter 5). Manuals in Archaeological Method,Theory and Technique: 201–218.

McGovern,Patrick E, Benjamin P Luley, Nuria Rovira, Armen Mirzoian, Michael P Callahan,Karen E Smith, Gretchen R Hall, Theodore Davidson, and Joshua M Henkin

2013  Beginning of viniculture in France. Proceedingsof the National Academy of Sciences of the United States of America 110(25):10147–52.

McGovern,Patrick E, Armen Mirzoian, and Gretchen R Hall

2009  Ancient Egyptian herbal wines. Proceedings ofthe National Academy of Sciences of the United States of America 106(18):7361–6.

McGovern,Patrick E, Juzhong Zhang, Jigen Tang, Zhiqing Zhang, Gretchen R Hall, Robert aMoreau, Alberto Nuñez, Eric D Butrym, Michael P Richards, Chen-Shan Wang,Guangsheng Cheng, Zhijun Zhao, and Changsui Wang

2004  Fermented beverages of pre- and proto-historicChina. Proceedings of the National Academy of Sciences of the United Statesof America 101(51): 17593–8.

McLaren, F,and J Evans

2002  The chemical identification of ancient britishbread flours: encountering and overcoming some of the obstacles. Civilisations49(1): 169–182.

Oudemans,TFM, JJ Boon, and RE Botto

2007  Spectroscopy of charred and non-charred solidorganic residues preserved in roman iron age vessels from the Netherlands. Archaeometry3(July 2006): 571–594.

Quigg, JMichael, Mary E. Malainey, Roman Przybylski, and Gregory Monks

2001  No Bones About It: Using Lipid Analysis of BurnedRock and Groundstone Residues to Examine Late Archaic Subsistence Practices inSouth Texas. Plains Anthropologist 46(177): 283–303.

Simms,Stephanie R., Francesco Berna, and George J. Bey

2013  A prehispanic Maya pit oven? Microanalysis offired clay balls from the Puuc region, Yucatán, Mexico. Journal ofArchaeological Science 40(2): 1144–1157.