Shoyu-brewing

Do you know how shoyu (soy sauce) is traditionally made? Rob and I had the chance last Saturday to have an inside look at one of the shops that specialises in shoyu. Since soy sauce features a lot in many Asian dishes, it was very insightful to learn how it is traditionally made. The lady shopowner was very animated and genki (energetic) and that certainly made it an interesting visit. Although the soy sauce sold in this shop is quite expensive (a small 150mL bottle fetches around 250yen (~AU$2.50)), the stuff tastes good and is very full-flavoured.

First, the soybeans are steamed/boiled and the wheat are roasted, and then blended together on a large table. A type of 'yeast' called koji (the same koji used for brewing sake) is then incorporated to the soybean/wheat mixture.

Boiling the soybeans and straining them:


Roasting the wheat and then processing the wheat using a grinding machine:


Combining the boiled soybeans, the roasted wheat and the koji, and airing/cooling the mixture on a table:


The soybean/wheat/koji mix is then kept in a dark room to allow the koji to grow, and when enough growth has taken place (a few days), the mix is poured into large tanks and mixed with brine. The atmospheric condition is quite critical for the growth, so the growth process is not usually done during the hot and humid summer. Then, usually the resulting moromi is then left to ferment for six months, but this particular shop has a fermentation process that takes two years. No wonder the stuff is very flavourful! This shop has 12 fermentation tanks (about 2m high), and no one goes in this area once the moromi are placed in them.

The 'growth' room:


and the huge fermentation vats:


So fast forward to two years later, and the fermented moromi is removed from the fermentation tubs and placed inside this 'rowing' contraption where it is compressed and the liquid extracted from the solids. We tasted both the liquid (shoyu) and the by-product cake and they were good. The solids tasted a little bit like miso (this part is usually discarded but some customers do request them).

That's our animated host demonstrating how to use the machine to extract the liquid


and the other side of the machine where the good stuff drips out:


After the demonstration, we were treated to some yummy shoyu-flavoured gelato - sounds like a weird combo, but it was quite nice. The shoyu flavour was very mild, and the gelato was pleasantly sweet. This visit was certainly the highlight of the day.