Tetujin·Vinegar Co.
Every bottle that leaves the Shigaraki brewery carries a paper trail — an independent Certificate of Analysis, a JAS audit record where applicable, and a scannable QR code that opens the brewing notes for that exact lot. This page is the long-form version of that promise, written for the visitor who reads the small print.
We do not ask you to take the vintage on faith. Acidity, amino-acid density, residual sugar, and the absence of caramel, preservatives, and dilution water are measured by an external laboratory and shipped inside every case. The koji mother culture that begins every fermentation has been continuously propagated in our cellar since 1817; the lot number on your bottle points to the brewer who signed off on its release.
Below: the four Certificates of Analysis indexed by product line, the methodology behind every figure, the JAS certification applied to one line only, and the three-step portal that takes you from a bottle in your hand to the brew record it came from.
Four product lines, each with its own COA template and acceptable-range table. The lot number printed on every bottle resolves to a single PDF in the archive below.
The flagship 12-month cedar-aged brown rice vinegar. Acidity tested at 4.8–5.0%; amino-acid density 1,420–1,580 mg/L. Six lots per year.
36-month cypress-aged unpolished rice vinegar. The single JAS-certified line in the catalogue (Cert. No. JAS-2024-1841-06). Gold Medal, Japan Vinegar Awards 2024.
Pressed from Aomori apples, fermented with the same Shigaraki-Hatchi koji culture, aged 18 months in chestnut. No "mother" added post-bottling.
The byproduct of first-press umeboshi, naturally fermented 14 months. Acidity sits higher than rice vinegar owing to the fruit's malic acid contribution.
Only the Junmai Black line currently holds JAS Organic certification (Cert. No. JAS-2024-1841-06), audited annually by the Shiga Prefecture Agricultural Inspection Office. The other three lines are produced to the same family-house standard but are not marketed under the JAS Organic claim.
Sampling is drawn at the bottling line, not at the aging barrel — a deliberate choice that captures the vinegar as the consumer receives it, after every transfer and adjustment the brewery permits itself. Three bottles are pulled per lot; the second bottle is shipped under chain-of-custody to the Shiga Food Sciences Institute in Kusatsu, twenty-two kilometres from the brewery.
The Institute measures five parameters against a published acceptable range: titratable acidity by 0.1 N NaOH titration; amino-acid density by the ninhydrin colorimetric method (reported as mg/L of total free amino acids); residual sugar by the Lane-Eynon titrimetric method; pH by calibrated electrode; and a qualitative absence screen for caramel colour (E150a-d), sorbate and benzoate preservatives, and added dilution water inferred from a deviation between measured Brix and labelled solids.
Results are returned to the brewery as a signed Certificate of Analysis within seven business days. A copy is bound to the lot record; a second copy is folded into the shipping carton; a third is published to the lot portal against the bottle's QR code. No bottle leaves the brewery without a passing COA on file. No COA is edited after signing — if a parameter falls outside the published range, the lot is held and either re-aged or re-blended under the brewmaster's annotation.
The methodology itself is not proprietary. It is published in full on this page so that any technical buyer, importer, or food laboratory may repeat the measurement against any Tetujin bottle and arrive at a comparable figure within the documented tolerance of the instrument.
The QR code printed on the back label of every bottle resolves to a lot-specific page in the Tetujin archive. Below is what the visitor sees on the other end of the scan.
A 12 mm quiet-zone code is printed beneath the lot number on every bottle. It encodes the lot string only — no personal data, no analytics — and resolves to a static HTTPS page in the archive.
The portal page opens with the lot string, the bottling date, the brewmaster's signature, the cedar or cypress barrel ID, and the month count from pressing to release. Below, the matching Certificate of Analysis is embedded as a downloadable PDF.
Each portal page links to the published lab methodology and lists the five parameters measured for the lot — acidity, amino-acid density, residual sugar, pH, and the absence screen — so the consumer can compare the figures printed on the label to the figures the lab measured.
You have now seen the four Certificates of Analysis, the JAS scope, the lab methodology, and the lot-portal flow. The next step is to read the same figures on a bottle in your own kitchen.
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