Koshu

As time goes by – drinkability and aging of Sake by Kai Draeger

Oct. 02. 2020
by Kai Draeger

Japanese Sake**, to evolve patiently in the bottle or to drink quickly?  In other words, what is the most suitable time for consumption (drinkability)?  The simple answer is that the brewer decides the best time for you.  Sake reaches its drinkability when it is released to the market.  By then, the brewer has achieved his/her aim to craft a Sake with the characteristics he/she has been looking for.  And the brewer wants you to drink it just like it is without waiting for it to evolve further in the bottle.

But what happens if you keep a bottle for longer?  You may have noticed that a Sake bottle does not come along with an expiry date on its label.  Does this mean that a bottle of Sake lasts forever?  Certainly not.  Sake loses its aroma and flavor profile over the time, especially fragrant Sake types like Ginjō and Daiginjō.  Each Sake has a maximum shelf life period to enjoy its original characteristics and the length of this period depends not only on the Sake but also a lot on how a bottle is stored.

Temperature has a high impact on Sake and many people claim that the perfect temperature to reduce maturation is around -5℃.  However, the majority of consumers stores Sake in a normal household fridge and the distinction between pasteurized and unpasteurized Sake can be a good guidance how to maintain drinkability.  Unpasteurized Sake (Nama-Zake) is very prone to change during storage due to the still active enzymes, yeast and other micro-organisms that remain inside the Sake even after pressing (filtering).  To slow down the still ongoing fermentation process and to avoid the loss of its fresh and lively character, unpasteurized Sake should be kept refrigerated at around 5°C and consumed within three to six months, open bottles within a few days.  Pasteurized Sake is more stable and can be stored in a cool place below 15 °C but should ideally be kept refrigerated at or below 8°C.  It should be consumed within one year, and open bottles within some days and a week.  Another factor to be aware of when storing Sake, is the exposure to sunshine and bright artificial light.  Light degrades the amino acids, causes discoloration and unpleasant aromas like that of burned hair within only a few days.  Last but not least, bottles should stand upright to offer a lower oxidation surface and to avoid any interaction with the closure, which is usually a metal screwcap or a foil lined stopper and only in rare cases made from glass.

    The clock for the drinkability of a Sake starts from the bottling date that you will find on any bottle.  Another date you can find on a bottle indicates the brewing year (BY), which usually starts in July and ends in April of the next year.  You may have noticed that some bottles on the market carry a BY far beyond their bottling year.

In general, Sake is often matured for six months to one year or longer to round up the aroma and flavor profile before release (bottling date) and let the stifling odor disappear that some Sake have after pasteurization.  A real evolution in the sense of a gradual development from a simple to a more complex form of Sake happens if Sake is matured for some years.  But we should not speak about an “evolution" of the original characteristics but instead about the development of new characteristics that turn the unmatured product into a different style of Sake.  

Although it is a different style, aged Sake is not a new style.  Aged Sake was already mentioned during the Kamakura period (1185–1333) and during the Edo period (1603 to 1868) aged Sake was traded as a luxury good.  Between 1868 and 1945 aged Sake was rare in the market.  Allegedly, the reason was a change in the Japanese tax legislation whereunder the tax was tied to the time of production instead of sale, which gave the brewers less incentive to store Sake longer than necessary.  After this taxation rule was abolished in 1945, some breweries started again to sell aged Sake.  However, aged Sake still accounts for a very small part of the Japanese market due to the low demand and low production volumes of the few breweries that age Sake at all.  On the foreign market, aged Sake is rare to get albeit there are some efforts on the way to change this soon.

In the Japanese language, aged Sake is referred to as Koshu, old Sake, or Chōki Jukusei-Shu, long term matured Sake.  When speaking about aged Sake, the term Koshu is often used for very ripe products with deep color and pronounced aroma.  However, the term is a bit ambiguous. It can be also used to distinguish Sake of the last BY from Sake of the current BY or can stand for Sake that has been unintentionally left on the shelf and went more or less undrinkable.  The term Chōki Jukusei-Shu, on the other hand, is a little bit clearer because it carries the notion of deliberate aging. This term is often used for lightly ripened Sake that have still some of the original flavor and taste characteristics. 

Up to this point, the terminology is still vague and there is no legal or generally valid definition of what aged Sake is, how it must be aged and for how long.  At least the private Japanese association for long term matured Sake (Chōki jukusei-shu kenkyūkai), has established some guidance for its members.  To differentiate aging amongst others from refinement, a minimum aging period of three years is required for Chōki Jukusei-Shu.  The group distinguishes between three types of aged Sake.  Kojuku, that is aged at ambient temperature and develops an aroma and a taste that is extremely different from the unaged original.  This method is often used for rich Junmai and some Honjōzō Sake and stands for a style that people would also refer to as Koshu.  The second category is called Chūkan, that is aged in combination of low and ambient temperatures with the result of a medium ripe Sake that has still a bit of the aroma and taste of the unaged original.  Junmai Sake and Ginjō or Daiginjō Sake with a restrained aromatic expression are often available as Chūkan.  The group’s third category is called Awajuku and represents the most elegant aging style. Awajuku is usually used for fragrant and distinctive Ginjō and Daiginjō Sake that are matured at or below 0 ° C. And believe me, it is possible to retain the fruity aroma and flavor of a Ginjō or Daiginjō Sake (Ginjō-Ka) in the bottle, albeit in a new interpretation without the fresh peaks of the unaged original.

Is any Sake suitable for aging?  In general, Sake with a higher degree of residual sugar, higher acidity, especially in amino acids, are very suitable for aging. The reason is the so called Maillard reaction, whereunder the residual sugar reacts with the amino acids and creates a new variety of aromas and flavors.  Sake that are generally difficult to age are unpasteurized Sake (Nama-Zake) and naturally cloudy Sake that still contain rice, koji and yeast residues (Nigori-Sake).  However, it is not impossible to age these microbiologically fragile products.  Long time matured unpasteurized Sake can result in an aroma profile of hazelnuts, malt and bacon, which is called the nama-hine fault, or in a more positive way, nama-juku, aged unpasteurized Sake.  Nigori Sake may also develop interesting lactic and cereal-like aromas and flavors.  Important factors for aging are temperature and time.  The higher the aging temperature and the longer the storage period, the more the aroma and flavor and the more the color of the original product changes.  Due to the resulting yellow-brown to almost black, nitrogen-containing, organic compounds (melanoids), the color of the original product changes slowly to gold, amber and dark brown.  Bottles can in principle be stored for ages and will continue to develop their profile, which makes aged Sake interesting for collection.  Open bottles should usually be consumed within six months.  Aged Sake may be kept at room temperature not above 15 ° but cold storage below 8°C is recommended for at least Awajuku styles. Nama-Zake and Nigori Sake, should be continuously kept at or below 0°C.

Aged Sake is complex when it comes to the nose and palate and you will find a wide variety of aromas and flavors that ranges from sweet notes (honey, brown sugar, molasses, caramel, vanilla and dried fruit) to butter, chocolate and coffee and nutty notes (almond and walnut), to spices (anise, clove, cinnamon, pepper and nutmeg) and savory notes (soy sauce, shiitake, pickled vegetables and bouillon).  Have a try, especially if you like sherry, cognac, port wine or rum or other aged beverages.

Aged products are available in many retail stores and there are also some bars specialized in this magnificent beverage.  Whatever Sake is calling your taste buds – old or new – the masters of these bars will fill your mind with their wisdom on this topic, and your stomach with some great aged Sake. Enjoy!

* Kai Draeger is a Sake enthusiast who lives and works in Tokyo. He is a Certified Sake Professional (CSP) and holds the WSET Level 3 Award in Sake. He is currently looking into aged Sake products and wants to share some of his observations. You may contact him under kaidraeger@mac.com and read more about Aged Sake under www.aged-sake.com.

** Japanese Sake (“Nihon-Shu”), hereinafter referred simply as to Sake.

© Kai Draeger September 2020.