Mirin, a sweet sake mostly used for cooking, is known in Japan as the king of condiments in virtue of its fantastic power to draw out the flavours of ingredients, giving a wonderful richness and depth to all kinds of cooking.

The History of Mirin

The production of mirin began some 500 years ago in Japan, during the Muromachi period, when it was used exclusively like a drink much like a fortified wine. However, containing yeasts from sake, this mirin would quickly turn sour. It was when shochu, a traditional Japanese distilled alcoholic liqueur, was introduced from Okinawa and Southern Kyushu that mirin evolved into its present form.

Using shochu as a base ingredient, mirin could be produced without losing its flavour, and its popularity began to grow. During the Edo period (1603-1868), mirin began to be incorporated into all kinds of meals, and quickly became an indispensable part of traditional Japanese cuisine and Kyoto’s intricate banquet food, kaiseki ryori.

Within mirin production, the area in central Japan known at the time as Mikawa emerged as the well-known area of production for mirin of superlative quality. Mikawa means three rivers, as it marks a spot where three major estuaries flow into Nagoya bay, and the good water in this area as well as its temperate climate are key in the making of top-quality mirin. The area’s proximity to the sea ensured that it had priority access to all the crucial raw materials, as well as the country’s major markets.

The Production of Mirin

Clearspring’s Mikawa Mirin suppliers, the Sumiya family in Hekinan City of Aichi Prefecture (the new name for Mikawa), have owned their own mirin company since 1910, and are the only company ever in Japan to have been awarded the diamond award by the Japanese Alcoholic Seasoning Association. Simple and orderly, the Sumiya family’s traditional brewery is steeped in the delicious aroma of maturing mirin.

Quite different to the frantic sake making procedure, pure mirin takes up to one year to make. The Sumiya family is dedicated to the leisurely and gentle procedure of traditional mirin from pure ingredients, which they have been perfecting for almost one hundred years.

As with many other traditional Japanese foods, the secret of excellent mirin lies in the quality of the koji culture, which is the basis of its brewing process. It is this koji which brings out the taste of the glutinous sweet rice used for mirin. The Sumiya family also produce their own koji.

To do this, the rice is washed and soaked, then steamed and cooled to the required temperatures. Next it is inoculated with koji spores and incubated on wooden trays for 48 hours. The incubating room is initially heated, but the koji then begins to generate its own heat, of temperatures of up to 35 degrees centigrade, and the room must be carefully monitored to ensure it doesn’t rise too high.

This koji is then mixed together with sweet glutinous rice and two kinds of shochu, also produced on the premises using sake lees. This mixture, known as ‘mirin moromi’, is then pumped into large enamel vats. Since moromi is always made in the middle of winter, the vats are wrapped in rice straw mats to keep them warm, and thus encourage good, even fermentation.

After being kept for three months, with periodic stirring to aid the function of the koji, the moromi is removed and put into cotton sacks for pressing. The mirin that emerges is left to mature for a further 150-200 days, during which time further sedimentation takes place.

Finally, when the mirin is ready, it is siphoned off from the top of the tank, filtered through cotton and bottled. The result is a heavenly sweet, amber-coloured seasoning that adds a delicate gourmet touch to even the simplest meals – no wonder that it has been awarded so many awards by the Japanese Alcoholic Seasoning Association. Although it makes an outstanding seasoning, authentic mirin can also be enjoyed as a drink. Its flavour is immediately pleasant and refreshing, and leaves no aftertaste.