Monday, June 11, 2018

The Search for the True Blue — Part 4

Modern Production
Elsner's breakthrough was the cause of great excitement among those Jewish scholars involved in this field. As a result, the past fifteen years have seen a wealth of publications, both religious and scientific, on the implications of this newly-found tekhelet. Even so, tekhelet remained confined to the realm of the theoretical for many years. That changed in 1993 when a trio of individuals established the P’Til Tekhelet Foundation to provide the blue dye to the general public.

They developed a manufacturing process which conformed to the specifications set forth by ancient religious texts and Jewish law. The dye is produced using M. trunculus snails obtained off the coasts of Greece, Spain, and France where they are commercially harvested as a food source (Israeli law protects all invertebrates in its coastal waters thus the native M. trunculus cannot be used).

Organic Synthesis
[Full disclosure: the following section has been edited and updated since the original writing.]

One might wonder why such an intricate procedure is utilized in the production of so simple a product. The chemical structure of tekhelet is well-defined and an elementary organic synthesis using modern techniques could provide the exact same molecule at a reduced investment of time and money. Why do Jewish scholars insist on extracting the dye from M. trunculus?

In the times of the Talmud the exorbitant cost of authentic tekhelet lead to the development of a counterfeit dye. The Talmud warns that this dye, called kala ilan, may not be used in place of tekhelet and that prospective buyers should only purchase their dye from a trusted expert as the two dyes were identical in appearance and the only way to distinguish between them was through a complicated chemical assay.18 The literature describes kala ilan as a plant derivative and it has since been positively identified as indigotin, popularly known as indigo.19 The reader will immediately note why tekhelet and kala ilan looked alike — they are chemically identical. But, if they are truly one and the same molecule, how can they can be distinguished through a chemical assay?

Although nowadays it is possible to extract and purify indigotin from either mollusks or plants and have the resulting dyes be indistinguishable, this was not always the case. In the ancient world, the process for preparing tekhelet from mollusks was markedly different than the preparation of indigo from plants. Different chemicals and techniques were used to extract the dye and the final products were not 100% pure but rather contained traces of both the source material as well as other compounds used in the preparation. The tests described in the Talmud may have been designed to distinguish between tekhelet and kala ilan based on these differences.20

At any rate, the Talmud expressly forbids the use of kala ilan. It must therefore be concluded that as far as Jewish law is concerned, the source of the material and the way it is prepared play a more important role in determining its religious viability than do its actual physical properties. This argument rules out the possibility of using an artificial synthesis and justifies the current procedure of preparing the tekhelet from M. trunculus.

18 See Babylonian Talmud, Tractate Menahot, p. 40a and 42b (Aramaic). 
19 Herzog, I. The Royal Purple, Keter, 1987, p. 94-96.
20 Sterman, Baruch. "Recent Postings regarding Tekhelet." Avodah Mailing List, 10-7-2001. Web, accessed 5-30-2018.

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