KAGOSHIMA, JAPAN: There's an explosion of black vinegar bars throughout Japan, as the beverage gains popularity as a health tonic.

You can choose from vinegar drinks mixed with fruit flavours, or even a glass of black vinegar laced with honey.

It's especially popular among young female office workers and it's because of its minerals and good balance of amino acid.

Many elderly Japanese are fast becoming fans as black vinegar is believed to help purify blood and cleanse arteries.

The brew from Kagoshima prefecture on the Southern tip of Japan is said to be among the best.

Tadaaki Kuramoto, Factory Chief of Sakamoto Brewery, said that some of the vinegar drinks have been brewed for more than a month. And the three ingredients are malted rice, steamed rice and fresh spring water.

All five senses are engaged in the production of black vinegar.

Mr Kuramoto said its colour is closely monitored, and workers must also ‘listen’ to the sounds made by the fermented brew, to tell just when to ‘harvest’ the vinegar.

But how different is black vinegar from the cheaper, and more readily available white version?

The black liquid is usually harvested after a year, double the fermentation period for the white liquid.

Kuramoto added: “We're using a process that dates back to the late Edo Period, to ensure that our vinegar tastes as good as it did long ago."

The vinegar is brewed in huge pots which can contain up to 30 litres of liquid each and Sakamota brewery has more than 50,000 of them.

With demand for black vinegar growing steadily, there're now eight breweries in the prefecture. -CNA/vm