Edited by Haruhiko Nakayama
The story of Black Vinegar
Outside fermentation and earthenware crocks

In the backyard of our black vinegar manufacturer, Ohyama Foods, there is a peculiar vista where a number of earthenware fermentation crocks partially buried outdoors making their half-appearance from earth (pictured left). The outdoor fermentation of vinegar by making use of warm climate is very unique and is only possible in the southern region of Japan, especially in Miyazaki and Kagoshima prefectures. Ohyama has been practicing outdoor vinegar manufacturing since their business was established in 1930.


The vinegar production at Ohyama Foods takes place semiannually: spring and autumn. For the first six months vinegar is fermented in crocks. After the crock fermentation, the vinegar is transported to an inside tank where it is aged for another six months. The shape of the Japanese ceramic crocks (wider opening with slim base) are mostly suitable for the fermentation –though they cannot stand on their own. This is why Ohyama buries crocks in the ground so the crocks can stand on its own. Burying crocks in the ground also generates a convective flow inside the crocks which enables the liquid temperature to stay convectively-cooled even over the summer time when the surface temperature on the crocks gets hot.  


Speaking of a little anecdote about vinegar making outside, a 5 Yen coin (made of copper and zinc) is placed on a paper lid at the very beginning of the vinegar production, and as the acetic fermentation advances, patina starts appearing on the coin (because copper and zinc get oxidized by acid generated by vinegar). Actually the condition of the 5 yen coin (how much it is being covered by patina) is the barometer to tell the completion of the acetic fermentation; the 5 yen completely being covered by patina is the sign that vinegar is ready for the next step, aging.

Two different Kojis


Ohyama Foods uses two different kinds of koji for different use applications. In the West, vinegar is meant be used mainly for cooking but here in Japan diluted vinegar is also consumed as a healthy drink. Ohyama uses white koji for vinegar intended for cooking use and black koji (an ancestor of white koji) for vinegar intended for drinking. Black koji makes vinegar more full body and becomes ideal drinking vinegar (you can use it for cooking if you want to bring out richness).

Black Koji

Spring water from the laurel forest

Another interesting feature is about the quality spring water Ohyama Foods uses for their mother water when making vinegar. Much of Aya, where Oyama Foods is located, is covered by the laurel forest (subtropical forest); as a matter of fact, it is the largest laurel forest existed in Japan. This laurel forest plays an important role as the water source forests, and Aya’s spring water was named as one of the 100 best spring waters by the Japanese government. According to Ohyma Foods, Aya’s spring water is categorized as soft water whose pH is 6.5 and it is very suitable for fermentation mother water.



Naturally-derived amino acids

In speaking about the health benefits by consuming black vinegar, there are two key components: amino acids and citric acid. The important fact is both are naturally-derived and not chemically-extracted. Black vinegar is said to abound in amino acids, and among them BCAA (branched-chain amino acids), which directly metabolized in the muscles, is highly regarded as sport nutrition. Combining with aerobic exercise, amino acids are said to help burn body fat.




Rich in citric acid that relieves fatigue


The other key component is citric acid. Vinegar in general contains acetic acid, and this acetic acid turns into citric acid when it enters the human body. Lactate, converted from sugar during exercise, is considered to restrict blood flow, and is found to be the cause for fatigue. Citric acid is said to function as fatigue reliever to help improve outherwise restricted blood flow. There are many other benefits with the combination of amino acids and citric acid (easing constipation, works to prevent arteriosclerosis process, and more). Although these are not scientifically-proved facts, the bottom line is black vinegar has been respected as a healthy food in Japan for generations.


Past, present and future

Oyama Foods not only produces black vinegar traditionally,  but also   incorporates their signature black vinegar in the hybrid products that are appealing to a wide range of individuals. Such products range from various types of flavored drinking vinegars and vinegar-related cooking condiments to supplements and a sport/energy drink. As the sky is their creative limit, the future of the traditional vinegar maker holds a silver lining.