Ingredients, dishes and drinks from Japan by Ad Blankestijn

Monday, December 21, 2015

Shoyu

Shoyu:

Soy sauce. しょうゆ、醤油。

Soy sauce is the basic condiment in the Japanese kitchen and is used in all sorts of dishes, in marinades, dipping sauces and also at the table. Soy sauce is made from soy beans, roasted wheat, salt and koji. Soy sauce boasts a hearty aroma and contains 15% to 20% salt (there are also low-salt varieties).

Although soy sauce has ancient roots (in the form of a fish sauce which is still used in S.E. Asia, a product called hishio or uoshi in Japan), it was only in the middle of the 17th c. developed in its present form. In fact, soy sauce started as a by-product of miso production, in towns like Yuasa, Tatsuno and on Shodo Island in Western Japan. In the 18th c., the soy makers in Noda and Choshi (Chiba Prefecture) also came up, as they were close to Edo. Different from miso, which can be made by small producers, or even in individual households, for soy production large industrial presses are necessary, which asks for a more large-scale, industrial approach.

There are various types of soy sauce:

Usukuchi shoyu & koikuchi shoyu
  • Tamari consists only of soybeans without wheat or with very little wheat. It is a thick, sweet sauce that is especially suitable as dipping sauce for sashimi, as the basis for teriyaki sauce, for tsukudani or for the coating of rice crackers. This is the original soy sauce until the mid-Edo period: as also the name indicates, it was the liquid that runs off miso as it matures, a byproduct from the fermentation of miso. It was originally obtained by pressing miso, but nowadays the production method is the same as for soy sauce, with as only difference that little or no wheat is used. Mainly produced in the Chubu region (around Nagoya).
  • Koikuchi shoyu (with an equal amount of soy beans and wheat) is dark in color and has a strong taste. This standard type is good for 82% of all soy sauce. As a true versatile all-purpose sauce it is also used at the table. Koikuchi shoyu was developed in the late 17th c. in the Kanto area by improving tamari by adding wheat to the production process (this was done in 1697 by Higeta from Choshi). Koikuchi shoyu is now produced in the whole country, but the production in the Kanto area is still the highest, with companies as Kikkoman (Noda), Yamasa and Higeta (both Choshi) - in the past, these companies could transport their products easily to Edo over the River Tone. Another production center is on Shodo Island in the Inland Sea, where the climate is very suitable (Marukin). 
  • Usukuchi shoyu is lighter in color but (against expectation) also 10% saltier. This type is mainly used in the kitchen and is good for 15% of all soy sauce. Usukuchi soy sauce is especially popular in Kyoto and the Kansai area, for example in clear soups, udon soup and in simmered dishes (nimono). As it is lighter in taste and color it doesn't clash with the light cuisine of Kyoto (where dashi is made only with kelp, without the addition of katsuobushi). The production process is slightly different, too: the wheat is lightly roasted; during fermentation, less koji and more brine is used; and at the end amazake or mizuame (glucose) is added. The fermentation is shorter than for koikuchi shoyu. An important producer of usukuchi shoyu is Higashimaru in Tatsuno (Hyogo Pref.).
  • Saishikomi shoyu or kanro shoyu is "twice-processed" or "sweet" soy sauce. Both flavor and color are very rich. The koji is mixed with koikuchi shoyu instead of brine. This type was developed in the town of Yanai in Yamaguchi Pref., and is now mainly produced in the Sanin area and Kyushu. It is used for sushi and sashimi. 
  • Shiro shoyu or "white soy sauce." Is lighter in color than usukuchi shoyu, obtained by mainly using wheat and very little soy beans (so the opposite of tamari). Is rather salty and also very sweet, Suitable for simmered dishes (nimono), suimono (clear soups) and chawanmushi. Developed in Hekinan in Aichi Pref.  
  • Genen shoyu and Usushio shoyu are soy sauces with "reduced salt," and "light salt." The first one usually has 9% salt (half of normal koikuchi soy sauce) and the second one 13%. 
  • Sashimi-joyu or Ponzu-joyu etc. These are not pure soy sauces, but sauces on the basis of soy sauce. In the case of the first one tamari, sake and mirin have been added to koikuchi shoyu to make a dip sauce for sushi. The second one is the same mix, but with the important addition of the juice of citrus fruits like yuzudaidai or sudachi. Ponzu is used as a dipping sauce for one-pot dishes. There are many varieties in Japanese supermarkets of such mixed sauces.
The production process of koikuchi soy sauce is as follows:

1. Equal parts of steamed soy beans and roasted and shredded wheat are mixed together.
2. Koji spores (Aspergillus) are cultivated for 3 to 4 days on this mixture. Koji spores have a high proteolytic capacity, i.e. they break up proteins into amino acids, and produce all sorts of enzymes which are important later on in the process. Other microbes contained in this culture include yeast and lactic acid bacteria.
3. Next brine is added to make moromi, the main mash, which is fermented and aged in large tanks. Instead of brine, also dry coarse salt can be used for dry fermentation. The enzymes in the koji now start working and transform the proteins in the soy beans into amino acids. They also change the starch in the soy beans and wheat into sugars. Lactic acid bacteria produce lactic acid and yeast makes ethanol.
4. The moromi is aged for several months. Through aging and secondary fermentation numerous flavor compounds typical of soy sauce come into being.
5. After it has been sufficiently aged, the moromi is pressed so that the pure soy sauce is separated from the lees.
6. This soy sauce is next filtered and pasteurized.

It is possible to cut corners in soy sauce production by chemical processes (using acid-hydrolyzed soy protein instead of the time-consuming fermentation process - this takes only 3 days), so select soy sauce that has been labeled "honjozo" or "100% genuine fermented." When using soy sauce for Japanese dishes, use only soy sauce produced by a Japanese maker.