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Everything you need to know about Koshu from Japan

If you like delicate wines, and you’re searching for the perfect partner for raw-fish dishes, then read our guide to Koshu – a grape from Japan that’s ideal for sushi.

Koshu is like a pinkier Pinot Gris or Gewürztraminer

While Japan works with a number of grape varieties, from widely planted hybrid red grape Muscat Bailey A to international varieties such as Merlot, Pinot Noir and Cabernet, and in whites, increasing amounts of very good Chardonnay, it is the Koshu grape that’s become the primary focus for Japanese vignerons looking to stand out in the market at home and abroad.

Why? Because Koshu is distinctive, uniquely Japanese, and a brilliant wine match for the flavours in Japanese cuisine, from the subtle characters of sea bass sashimi to the strong, umami flavours found in sea urchin.

And, if you want to test this out for yourself, come to a masterclass this Monday, at London’s Asia House, to see how a range of Koshus complements Japanese food, from salmon nigiri to scallop sashimi, beef teriyaki to pickled ginger – or, just to show Koshu’s versatility, a spoon of the finest Caspian Caviar.

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So where does Koshu come from?

Koshu is believed to have arrived in Japan via the Silk Road from the Caucasus around 1,000 years ago, but it wasn’t until the 1870s that the grape was used to make wine – it had previously been grown for eating.

But the use of Koshu is inextricably linked to the birth of the Japanese wine industry, because the country’s first bottles of wine were made with the grape, and hailed from the city of Kofu – in the heart of the Yamanashi wine region, where to this day, 95% of all Koshu is grown.

What is Koshu?

It is a hybrid grape, believed to have originated naturally by a crossing of the European Vitis vinifera and an Asian Vitis species – although Koshu contains over 70% of the former.

It excels in Japan’s humid conditions, due to its naturally thick-skins, and produces wines of finesse. In 2009, Koshu of Japan was founded to champion the grape, and in 2013 it was recognised by the OIV, adding greater impetus to Japanese wine producers to promote the variety more widely.

What does it look like?

There is something so distinctly Japanese about the way Koshu looks. With beautiful deep-pink berries, it complements the slightly paler shades of the cherry blossoms that Japan is so famous for. In essence, Koshu’s colouring is similar to Pinot Gris or Gewürztraminer, albeit with a slightly deeper pink.

Where is it grown?

Almost all of Japan’s Koshu is grown in the Kofu basin beneath Mt Fuji, in the Yamanashi Prefecture

Koshu’s primary growing area is Yamanashi, which is a basin-shaped viticultural region, with vines on the lower slopes of the surrounding mountains. Landlocked, the area is protected from the Pacific ocean’s prevailing winds, rainfall, and typhoons by the perfectly cone-shaped, snow-capped, volcanic wonder that is Mount Fuji – the most powerful visual symbol of Japan.

Nevertheless, this is a wet, humid region. While Yamanashi’s vineyards like on the 35th Parallel North, which runs through California, southern Spain and Italy, this part of Japan differs from these wine regions due to the incidence of summer rainfall, with around 80% of the 800-1000mm of precipitation of Yamanashi falling during the growing season. Furthermore, Yamanashi’s viticutlural heartland, Katsanuma, is one of the warmest places in Japan. Combine the heat, and summertime rainfall, and Yamanashi is more like Australia’s New South Wales, particularly Hunter Valley, than it is somewhere like Sonoma.

Koshu, however, thrives in Yamanashi, not only due to its rot-resistant skins, but also due to its natural adaption to the fertile clay soils of the area, which, importantly, overlay a free-draining volcanic base, preventing waterlogging.

How is it grown?

In keeping with Japan’s reputation for precision in technology, the country’s viticulturists go to extraordinary lengths to protect the Koshu grapes, choosing to train them high in pergolas, improving airflow around the bunches, while also shading the grapes from temperature extremes.

They also protect the Koshu grapes from summer rainfall with little wax paper hats stapled together above each bunch, ensuring that the water doesn’t get inside the bunches. Otherwise, the water might start the spread of rot, which would spread rapidly in this warm and damp climate.

It’s an effective, if quite expensive technique, not used anywhere else in the world. As for the rainfall that does wash onto the ground, the free-draining soils of the Yamanashi area, many of them volcanic in origin, ensure that the berries themselves don’t swell too much, preventing the resulting wines from suffering from dilution.

What does it taste like?

Koshu wines are often said to have a taste of citrus, like the yuzu ‘orange’ of Japan

Koshu-based wines are delicate. Naturally around 11% ABV – and rarely above 12% – they are never tiring to drink, or forceful in character, but deliver something subtly intriguing.

In essence, the wines made from Koshu tend to have a combination of flavours, from citrus (particularly Japanese yuzu) to yellow fruit, and in general, to draw comparisons with well-known European whites, have some of the flavours of Muscadet, with its freshness and breadiness – the Japanese tend to give Koshu relatively extended lees contact – but also Albariño, with its lime-acid and peach fruit. Koshu also has something more unique, in the form of a gentle salty note, as though someone has added a drop of soy to the glass.

What are the main grapes Koshu is compared to?

Over the years, a number of comparisons have been drawn between Koshu and other European grapes. Most common among these are Muscadet’s Melon de Bourgogne, along with Semillon – particularly when sourced from Australia’s Hunter Valley – along with Albarino from Galicia in Northern Spain. Notably, all these grapes tend to come from damp, coastal regions. But Koshu can also resemble light, dry styles of Chenin Blanc from both the Loire and South Africa, as well as Pinot Blanc from Alsace. More obscure comparisons db has encountered from sommeliers and wine writers include Chasselas from Switzerland’s cool Alpine sloes, Arinto from the exposed vineyards of the Azores, and Feteasca Alba from Romania.

What are the styles of wines Koshu can produce?

Koshu does, however, produce wine in a range of styles, ensuring it matches different tastes, and rewards exploration. Some of this diversity relates to particular sites, where certain aspects and soils – particularly if they are free-draining – produce wines of great intensity and individuality. One of these is the Misawa vineyard in Akeno, where celebrated Koshu producer Grace makes the most of high altitude – coupled with, unusually, vertical shoot position training – to produce a remarkably intense, peachy Koshu. Another, the Isehara vineyard from brilliant Koshu producer Katsunuma, yields a sought-after example bursting with pink grapefruit, not unlike a top-end Sauvignon Blanc from the Loire.

However, much of the most obvious variations in Koshu wine style comes from practices in the cellar. As mentioned above, lees contact can be used to build in a bready complexity, as well as more texture to the naturally light-bodied wine, and with great success – much like the techniques used in Muscadet with the delicate Melon de Bourgogne grape.

Barrel fermentations and ageing, including new oak, albeit in low proportions, can yield surprisingly successful results with this subtle variety. The peanut character derived from high-quality barriques seems to marry well with the lemon and peach flavours of Koshu, in the same way sweet oak complements ripe Sauvignon Blanc in Bordeaux.

Grande Polaire produces a successful example, but in my view, the ultimate barrel-influence Koshu comes from Katsunuma Winery – called Aruga Branca Pipa. To carry with the oak-sourced flavours, this producer freezes the grapes to concentrate the peach and grapefruit notes in its best Koshus.

But it’s not just isolating particular plots or playing with lees and oak contact in the cellar that yields different expressions of Koshu. Some of the most notable wines come from extended skin contact – Koshu produces particularly good ‘orange wines’, coming in a range of hues, from light amber to egg-yolk coloured, cloudy wines. Gently grippy, often with aromas of smoked tea leaves, these are complex, versatile expressions that are gaining popularity in Japan, where there is a strong demand for ‘low-intervention’ wines (more so than organic or biodynamic certified products). Mercian and Lumière make particularly good skin-contact Koshus.

A further interesting and refreshing use for Koshu is in the creation of sparkling wines. Lumière crafts a delicious traditional method fizz with the grape, with the persistent mousse augmenting the citrus freshness of Koshu on the palate.

In short, there’s almost nothing that Koshu makers haven’t tried, with the new wave of winemakers now also looking to make Koshu with no added sulphur, as well as trialling new fermentation vessels, from concrete eggs to amphorae – yes, the experiments common in the cellars of Western Europe are also to be found in this far-Eastern outpost for winemaking.

What is Koshu’s food-pairing potential?

Sparkling Koshu and scallop sashimi is a brilliant combination

It’s not just curiosity that is motivating Japanese Koshu producers, whose spiritual home is Yamanashi, to try new things with this grape. They are driven by a desire to create wines that will pair successfully with the full range of flavours in Japanese cuisine, from the extremely delicate to the strong and challenging. One aspect that’s clear, however, is the brilliant combination of the salty-citric nature of Koshu and Japan’s raw-fish-based food.

This may be by accident, rather than design, but it is real; the tangy Koshu wines enliven the palate after sashimi, preparing the mouth for a dashi dish, or cutting through the residue of sticky rice in sushi. The Koshu helps with the consumption of such food, and the salty character of the dishes elevates the Koshu, bringing out more intensity.

And the likes of sparkling Koshu is an ideal accompaniment to the more subtle styles of raw fish-based Japanese food, where traditionally promoted wine matches such as oily Pinot Gris or aromatic Gewürztraminer would overpower such cuisine. However, where the much more powerful dashi-flavoured fare is on offer, requiring something weightier, one can opt for a Koshu expression with extended lees-contact or some additional skin contact.

One remarkable pairing is the intensely salty, creamy sea urchin – called ‘uni’ – with a Koshu orange wine. Another extraordinarily successful discovery for me was roast Wagyu beef and ginger paired with the aforementioned Aruga Branca Pipa from Katsunuma – proving the versatility of this grape, grown in Japan for around nine centuries before its winemaking capabilities were realised.

However, wines made from Koshu tend to struggle to pair successfully with dishes incorporating butter and cream, two ingredients that may be common in the cuisine of France, but not used in Japanese cooking.

Where can you try Koshu in the UK?

Koshu is just starting to appear in restaurants in the UK as sommeliers discover its appeal. Pioneer for Koshu in the UK was the late Gerard Basset MS, MW, who once poured Koshu from Grace at his hotel in the New Forest, called Terravina. And that was by the glass. Today, thanks to research commissioned by db and provided by Wine Picker, one can find Koshu at the following places in the UK:

  • Sexy Fish, London
  • The Lion & Pheasant Hotel, Shrewsbury
  • La Trompette, London
  • Union Street Café by Gordon Ramsay, London
  • The Swan, Shakespeare’s Globe, London
  • Hide, London
  • Heddon Street Kitchen, London

As for national distribution, sadly there is no supermarket currently carrying a Koshu, although, until fairly recently, Marks & Spencer sold the Sol Lucet Koshu from Kurambon.

Why should you want to try or stock Koshu – a final thought?

Well, Koshu offers an intriguing combination: pale pink berries in the shadow of Mount Fuji, grown with painstaking attention to detail, and producing something that’s delicate, fresh and with a touch of umami.

It has a subtle appeal, complexity, and an ability to pair so successfully with one of the world’s most popular and revered cuisines – Japan’s raw-fish-based food.

It’s also the emblematic of Japan’s fast-emerging wine industry.

And, it is right on trend with demand in mature wine-drinking markets, where the call is for something light in body, low in alcohol, refreshing, and authentic.

Koshu – a summary

  • It is thought that Koshu’s origins in Japan can be traced back to 1186 when it was discovered growing wild at Katsunuma in Yamanashi prefecture.
  • It is a hybrid grape, believed to have originated naturally by a crossing of the European Vitis vinifera and an Asian Vitis species.
  • According to Wine Grapes (Robinson et al), Koshu’s DNA profile does not match any other known variety and its exact origin remains unknown.
  • Koshu produces medium-sized bunches of large, thick-skinned, pink-tinged berries.
  • The grape has been favoured for a long time in Japan’s humid climate because it is resistant to botrytis bunch rot. > Koshu is Japan’s most planted grape, and 95% of plantings are found in Yamanashi prefecture.
  • Koshu produces delicate white wines that rarely exceed 12% ABV.
  • The grape can also be used to produce richer versions when grown in low-yielding sites, or if cellar practices allow – with techniques including extended skin contact and/or lees contact, barrel fermentation and cryoextraction.
  • The grape can also be used to make quality sparkling wine.
  • Its range of styles, from the lightest to fullest, are particularly good complements to Japanese raw-fish cuisine, from subtle types to the salty, creamy sea urchin ‘uni’.
  • In 2009, Koshu of Japan was founded to champion the grape, and in 2013, Koshu was recognised by the OIV.

Koshu currently available to buy from wholesalers in the UK

The wines of Chateau Mercian are now imported to the UK by Boutinot

  • Château Mercian, Fuefuki Koshu Gris de Gris, 2018
  • Château Mercian, Yamanashi Koshu, 2018
  • Grace, Koshu Private Reserve, 2018
  • Haramo, Koshu, 2017
  • Katsunuma, Aruga Branca Issehara, 2017
  • Katsunuma, Aruga Branca Pipa, 2016
  • Kurambon, Natural Koshu, 2018
  • Kurambon, Sol Lucet Koshu, 2018
  • Lumière, Prestige Class Orange, 2018
  • Lumière, Sparkling Koshu, 2017
  • SoRyu, Curious Type N Koshu, 2018

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