Numbing extracts are not meant for eating. Or are they? This paper explores the history of defining 麻 as a chemical flavor in the mid-twentieth century. For scientists who studied the tongue, “spice” was not a category of taste. Yet, 麻 and 麻辣 remained as a robust category of sensation in varieties of “East Asian” foods. To claim the particular characteristics of this sensation, chemists distilled juices from the skin of the pepper tree (or Xanthoxylum piperitum as it was known at the time) and named it hydrosanshoöl, in which hydro and sanshoöl together roughly meant “pepper tree water.” In the naming of tree-bark juice, chemists had maintained sanshoöl from the characters 山椒, which was a version of peppercorn similar to those scattered across the mountainous valleys of Shanxi. Given that national discourses that often obscure multifaceted origin stories of plants and plant products (such as Mao’s announcement that the red pepper was the true revolutionary food, when the pepper had historically made its way to his home province of Hunan via Spanish and Portuguese trade routes in the seventeenth century), this paper instead introduces a new cast of characters working in the laboratories, gardens, and kitchens of Gifu and Tokyo. I treat peppercorn neither as a revolutionary food nor an object enmeshed in discourses of Sichuan authenticity and instead argue how varieties of the plant and versions of its extracts transformed beyond national discourses in the People’s Republic.