"Ranjatai" aromatic wood that captivated rulers: The Imperial Household Agency Shosoin Office determines its fragrance components and age

The fragrance components and the age of the tree from which "Ranjatai" came have been determined. This log, stored at the Shosoin Repository, is said to have been coveted and cut by rulers such as Oda Nobunaga and Ashikaga Yoshimasa. Experts measured it using the latest equipment, including the large synchrotron radiation facility "SPring-8" and gas chromatography. The wood was from a tree that grew from the late 8th to late 9th centuries, and contained about 300 different components, including vanilla, mixed with the sweet fragrance of a plant called labdanum as a base. The Imperial Household Agency Shosoin Office stated that "based on these research findings, we would like to investigate other aromatic woods as well."

At the Shosoin Repository in Nara City, many treasures have been carefully preserved since the Nara period under the "Imperial Seal System" that manages the opening and closing of the treasure house doors with the Emperor's permission. Among these, Ranjatai is an aromatic wood with a history of being cut by various rulers and was originally known as "Ojukuko." It is a type of aromatic wood called "agarwood" that grows in the mountainous regions of Southeast Asia, weighing 11.6 kilograms and measuring 156 centimeters in length. The characters for "Todaiji Temple" are within the characters for Ranjatai, and it is believed to have been named through the wordplay that was popular during the Muromachi period.

The Shosoin Repository conducts the inspection, preservation, and recording of treasures, and began a project last year based on the question: "As this is an aromatic wood, it is also important that we record its fragrance. Can we somehow convey this to future generations?" Rikiya Nakamura, Head of the Conservation Division at the Shosoin Office, said, "When you get close to Ranjatai, you can faintly detect its fragrance. It's remarkable that it still has such a fragrance after more than 1,000 years. None of the other treasures retains any scent."

The items to investigate were identified as: the age of the aromatic wood, the source of its fragrance, the components of its fragrance, and how the fragrance is perceived. First, when the age was examined using radiocarbon dating, it was found that the tree had grown from the late 8th to late 9th centuries. Since the type of tree that Ranjatai comes from does not exist in Japan, it is believed to have been cut and brought from Southeast Asia by ship.

Next, the Shosoin Office commissioned researchers at Kyoto University to investigate which part of the wood produces the fragrance. Since the Shosoin Repository preserves fallen fragments of Ranjatai, they first made sections from the fragments and observed them under a microscope. Then, they brought the fragments to "SPring-8," operated by the RIKEN SPring-8 Center at Sayo Town, Hyogo Prefecture, and photographed the fine surface structure using micro X-ray CT.

As a result, it was found that the tissue called the "inner phloem," which differentiates from the vascular cambium formed during the secondary growth of plants, had been damaged, causing the synthesis of fragrance components. The vascular cambium is the meristematic tissue responsible for tree growth.

Component analysis was then conducted. When examined in detail using gas chromatography-mass spectrometry, 3-phenylpropionic acid was found to be the main component. 3-phenylpropionic acid is a substance that is difficult to dissolve in water but dissolves in ethanol. Since more than 300 other substances were detected, they were divided into those with fragrance and those without. Among the fragrance components, labdanum, which has a sweet scent, was detected in large quantities.

Finally, to recreate the fragrance, they relied on human olfaction. They sought the cooperation of experts called perfumers who blend fragrances. They had the perfumers smell Ranjatai's fragrance and memorize it. Based on that olfactory memory, they added sweet vanilla-type fragrances and spicy anise-type fragrances to the labdanum that was detected in large quantities, ultimately creating "Ranjatai's fragrance recreated in the Reiwa era."

Nakamura recalled: "The fact that we were able to recreate the fragrance means we can pass records down to future generations and preserve it. We have established a system that uses high levels of technology and accurate machinery, and the power of science was amazingly helpful." The Shosoin Repository preserves other materials used for scents, and it may be possible to use this method to analyze these too.

This "recreated fragrance" can actually be smelled at the special exhibition "Shosoin THE SHOW: Japanese Imperial Treasures. Experience the history and the miracle!" (September 20 - November 9) being held at the Ueno Royal Museum (Taito City, Tokyo Prefecture). Ranjatai Fragrance Cards" (880 yen) with the fragrance infused into paper will also be sold at the museum shop.