Pulque production from fermented agave sap as a dietary supplement in Prehispanic Mesoamerica

Abstract

Although in modern societies fermented beverages are associated with socializing, celebration, and ritual, in ancient times they were also importa`nt sources of essential nutrients and potable water. In Mesoamerica, pulque, an alcoholic beverage produced from the fermented sap of several species of maguey plants (Agavaceae; Fig. 1) is hypothesized to have been used as a dietary supplement and risk-buffering food in ancient Teotihuacan (150 B.C. to A.D. 650). Although direct archaeological evidence of pulque production is lacking, organic residue analysis of pottery vessels offers a new avenue of investigation. However, the chemical components of alcoholic beverages are water-soluble, greatly limiting their survival over archaeological timescales compared with hydrophobic lipids widely preserved in food residues. Hence, we apply a novel lipid biomarker approach that considers detection of bacteriohopanoids derived from the ethanol-producing bacterium Zymomonas mobilis for identifying pulque production/consumption in pottery vessels. Gas chromatography-mass spectrometry selected ion monitoring (m/z 191) of lipid extracts of >300 potsherds revealed characteristic bacteriohopanoid distributions in a subset of 14 potsherds. This hopanoid biomarker approach offers a new means of identifying commonly occurring bacterially fermented alcoholic beverages worldwide, including palm wine, beer, cider, perry, and other plant sap- or fruit-derived beverages [Swings J, De Ley J (1977) Bacteriol Rev 41(1):1-46].

Keywords: Mexico; hopanes; pine resins.

Fig. 1.

(A) Maguey plant (Agave salmiana), (B) maguey sap (aguamiel) pooled within a maguey in the process of sap extraction, and (C) man transferring pulque to a 2.5-L container for sale in Apan, Mexico.

Fig. 2.

(A) Major complex hopanoids in ethanol producer bacterium Z. mobilis (16). (B) Possible diagenetic products and transformations of complex hopanoids (17).

Fig. 3.

Partial gas chromatograms of total lipid extracts from pottery from the locality of La Ventilla. (A) Crater: characteristic distribution of plant waxes (LV-058). (B) Amphora: abietic acid derivatives (LV-014). Drawings of representative (C) crater and (D) amphora vessels. A, n-alkane; F, fatty acid methyl ester; OH, n-alkanol; OH C₃₂, biomarker of maize (21); IS, internal standard. Lipid extracts were run in different GC temperature programs to improve chromatographic peak resolution.

Fig. 4.

Biomarker distributions observed in potsherds from Teotihuacan, projected as scores on the first two components from principal components analysis.

Fig. 5.

GC-MS selected ion monitoring (m/z 191) showing hopane distributions (C₂₉–C₃₄) in (A) amphora from La Ventilla (LV-100), (B) replica pot and (C) alumina saturated with pulque after incubation, and (D) alumina (blank). Chromatographic peak denoted by a filled star corresponds to diploptene, another bacteriohopanoid present in pulque; however, it is highly susceptible to degradation and is thus absent in the archaeological amphorae.