Eradication of Contaminant Starch Granules from Synthetic Calculus: A Decontamination Protocol for Ancient Starch Research

Dental calculus provides ancient starch research a niche where granules may be adsorbed to minerals, coated, overgrown, entrapped or protected from chemical degradation. While encapsulation offers protection from degradation, it does not shield the sample’s surface from contamination. The most common approach to retrieving microbotanical particles from archaeological calculus has been the direct decalcification of the sample, after a cleaning stage variously consisting of immersion in water, acids, and mechanical dislodgment via gas, sonication, and/or toothbrushes. Little is known about the efficiency of these methods for a complete removal of sediment/soil and unrelated microbotanical matter. In this paper, controlled laboratory experimentation leads to a decontamination protocol to eradicate starch granules that have been adsorbed to artificially created calculus. Several concentrations of acids, bases, and enzymes were tested at intervals to understand their potential to gelatinize and fully destroy starch granules; arriving at a procedure that effectively eradicates modern starch prior to dissolution without damaging the matrix or entrapped starch microremains. This is the first attempt at creating synthetic calculus to understand and systematically test effective decontamination protocols for ancient starch research. We recommend immersion of dental calculus in 1ml of sodium hydroxide of 2% w/v solution 24h for a complete eradication of contaminant starch granules.