What is sudachi?

Sudachi (Citrus sudachi Hort. ex Shirai)

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What is sudachi?

Sudachi (Citrus sudachi Hort. ex Shirai) is a small but mighty citrus fruit that is widely cultivated in Tokushima Prefecture, adjacent to Kochi Prefecture, famous for its yuzu citrus. The exact origins of sudachi are not fully known, it is believed to be a mutation of the yuzu citrus (C. junos), a hybrid of the ancient citrus papeda (C. ichangensis) and mandarin (C. reticulata), or a hybrid of yuzu and Tachibana orange.

While yuzu is the most popular citrus fruit in Japan, sudachi (すだち) is a close second, and for good reason. Its unique tart and refreshing flavour makes it a versatile ingredient in Japanese cuisine, particularly in ponzu sauce, sashimi, and grilled meats. The compact size and thin skin also make it easier to handle and use in cooking.

In Tokushima Prefecture, sudachi cultivation is a significant part of the local economy. Farmers take great care to grow high-quality sudachi fruit, which has helped drive the annual sales of this citrus fruit to 2.2 billion yen or 16 million USD. With its distinct flavour and versatility, sudachi is a valuable part of Japanese culinary culture.

At a glance
Family: Rutaceae
Botanical name:
Citrus sudachi Hort. ex Shirai
Native to: Japan
Common names: Sudachi, Japanese sour citrus
Lifespan: Evergreen tree
Mature height: 3 – 5 metres
Type of citrus: Sour citrus, Japanese fragrant citrus
Flower colour:
White
Leaf colour:
Green
Fruit colour: Green to orange
Bloom time: Spring and summer
Soil: Free-draining
Humidity: High
Propagation: Cuttings
Care level: Moderate

 

Sudachi is a small, green fruit that weighs about 40 grams, roughly the size of a golf ball. It is famous for its tangy and sour taste and refreshing aroma, which make it a prized ingredient in Japanese cuisine. Sudachi juice is commonly used to enhance the flavour of sashimi, grilled fish, and ponzu sauce, which is a popular dipping sauce made with soy sauce, mirin, and sudachi juice.

The unique aroma of sudachi is due to the presence of limonene and terpene hydrocarbons, which are responsible for its characteristic citrus scent. In addition to its culinary uses, sudachi is also valued for its high levels of vitamin C, making it a popular ingredient in drinks and health supplements.

The name sudachi loosely means ‘vinegar citrus’ and is a contraction of the word sutachibana, which means ‘vinegar Tachibana, which refers to the fruit’s tart and acidic flavour, which is similar to vinegar.

History

Sudachi has a rich history dating back to the Edo period (1603-1867), where it was grown in home gardens and vacant land. It was described under the name “Reman” by the renowned Japanese philosopher Ekiken Kaibara.

Commercial production of sudachi began in the 1960s and with the introduction of greenhouses and long-term cold storage in the 1970s, it became available year-round. The Tokushima Prefecture government even supported local growers of unshu mandarin oranges to switch to sudachi as the price of mandarins had slumped.

The significance of sudachi in Tokushima Prefecture is evident with the designation of its fragrant, white flower as the prefecture flower on October 4, 1974. Sudachi-kun, a citrus-fruit-headed mascot of Tokushima Prefecture, was also developed and introduced at the 48th National Athletic Meet in 1993 and has remained a beloved mascot ever since.

In Kamiyama Town, a 200-year-old sudachi tree still bears fruit, a testament to the resilience and longevity of this citrus fruit.

What is the difference between sudachi, yuzu and kabosu?

Kabosu and sudachi side by side
Kabosu (left) and sudachi (right)

Sudachi is the smallest fruit among sudachi, yuzu and kabosu, with an average width of 4 cm. It has a tart and acidic flavour and is used when still green as a seasoning, garnish and to compliment dishes such as sashimi, grilled fish, and of course ponzu.

Yuzu has a more complex flavour profile with a mix of tartness, bitterness and sweetness. It is used to add a citrus flavour to dishes, sauces, marinades and dressings.

Sudachi is also confused with kabosu due to their similar appearance, however, kabosu, which is cultivated in Oita Prefecture, is considerably larger, weighing in between 80 – 150 grams and approximately the size of a tennis ball.

Despite its lime-like appearance, sudachi is a different species of citrus from lime and is classified as a ‘sour citrus‘, or in Japan, where it, along with yuzu and kabosu, are collectively referred to as Kosan Kankitsu, which means ‘flavorful acid citrus‘.

What does sudachi taste like?

Sudachi is tart and sour with a slightly sweet aftertaste, with a taste often described as a cross between a lime and a grapefruit. The juice is used to enhance the flavour of dishes, and the fruit is generally too tart to eat raw.

Limonin is a compound present in the pulp and peel of sudachi responsible for the bitter taste of sudachi. It is a type of limonoid that acts as a defense mechanism to deter herbivores and insects from feeding on the plant.

What type of citrus is sudachi?

While sudachi has a similar appearance to that of a lime, it is actually a sour citrus, or Japanese fragrant citrus (vinegared mandarin oranges). There are 40 types of Japanese fragrant citrus, including amanatsu, banpeiyu, budoukan, buntan, chukanboke, daidai, mikan, kinkan, okitsu, ponkan, sanbokan, shikwasa and yuzu. These citrus varieties are sour, highly fragrant and typically not eaten raw, but used as seasoning by squeezing the juice into dishes.

Uses

Sudachi uses
Soba with the slice of Citrus sudachi

Sudachi is a versatile fruit that can be used in place of lemon or lime to add acidity to dishes. In Japanese cuisine, it is used as a garnish or added to sauces and dressings. Sudachi juice adds tartness to sashimi to compliment the fresh flavour of raw or cooked fish. It can be added to a dipping sauce or garnish for soba and udon noodles as well as tempura and used as a replacement for vinegar. Finely grated or sliced sudachi are served as condiments. In Tokushima Prefecture, sudachi is added to miso soup and sake (Japanese wine) to add flavour.

Ponzu sauce is a popular citrus-based sauce made up of sudachi, yuzu, lime and orange juice, soy sauce, rice vinegar and sugar. It is commonly used as a salad dressing, a dipping sauce or a marinade for chicken or seafood. Sliced sudachi is served with grilled Pacific saury, smoked and fermented skipback tuna (katsuobushi), horse mackerel (aji) and Japanese butterfish (boze).

In recent years, sudachi has also been used in hard candy, gummies and in shochu, a Japanese distilled beverage.

Western uses:

Sudachi peel offers a versatile and zesty addition to a range of culinary creations. When candied, this fragrant peel can be a delicious inclusion in cakes, and muffins, or even used as a topping for fresh yogurt or ice cream. Sudachi can serve as a refreshing substitute for lemons or limes in cooked fish, offering a unique flavour profile to meringue pies, marmalades, and sorbets.

For an Italian-inspired twist, Sudachicello (a Sudachi-based limoncello) can be a delightful addition to any liquor cabinet, while sliced and dried wheels can infuse alcoholic and non-alcoholic beverages with a subtle yet tangy citrus flavour. For a finishing touch on sashimi, combining the dried peel with salt produces a distinctively flavoured seasoning.

Sudachi recipes

Sudachi Citrus Salad Dressing
Ingredients:

  • 1/4 cup sudachi juice
  • 1/4 cup olive oil
  • 2 tbsp honey
  • 1 tbsp soy sauce
  • 1 tbsp grated ginger
  • Salt and pepper to taste

Instructions:

  • In a small bowl, whisk together sudachi juice, olive oil, honey, soy sauce, grated ginger, salt, and pepper.

Notes:

Serve with chicken or fish.
Sudachi Marinated Grilled Chicken
Ingredients:

  • 4 boneless, skinless chicken breasts
  • 1/4 cup sudachi juice
  • 1/4 cup soy sauce
  • 2 tbsp honey
  • 2 tbsp minced garlic
  • 1 tbsp grated ginger

Instructions:

  1. Mix sudachi juice, soy sauce, honey, minced garlic, and grated ginger in a bowl.
  2. Add chicken breasts, coating them well in the marinade.
  3. Marinate for at least 30 minutes or up to 2 hours.
  4. Preheat grill to medium-high heat. Grill chicken for 5-6 minutes per side, or until cooked through.
  5. Let rest for a few minutes before serving.

Notes:

Serve with steamed rice, steamed vegetables, Asian coleslaw, noodles and cucumber salad.
Sudachi Citrus Vinaigrette
Ingredients:

  • 1/4 cup sudachi juice
  • 1/2 cup extra virgin olive oil
  • 1/4 cup white wine vinegar
  • 2 tbsp minced shallots
  • Salt and pepper to taste

Instructions:

  1. In a small bowl, whisk together sudachi juice, extra virgin olive oil, white wine vinegar, minced shallots, salt, and pepper.
  2. Drizzle over your favourite salad or use as a marinade.
Sudachi Citrus Salsa
Ingredients:

  • 1/2 cup sudachi juice
  • 1/2 cup chopped tomatoes
  • 1/4 cup finely chopped red onion
  • 1/4 cup chopped cilantro
  • 1 jalapeño, seeded and minced
  • Salt to taste

Instructions:

  1. In a medium bowl, combine sudachi juice, chopped tomatoes, red onion, cilantro, jalapeño, and salt.
  2. Mix well and serve with tortilla chips or as a topping for grilled fish or chicken.
Sudachi Citrus Pie
Ingredients:

  • 1 1/2 cups of finely ground digestive or hobnob biscuits
  • 100 g melted butter
  • 1 cup sudachi juice
  • 395 g can sweetened condensed milk
  • 3 large egg yolks
  • Whipped cream for topping

Instructions:

  1. Preheat oven to 350°F (175°C).
  2. Blend the digestive biscuits until they are crumbs, and transfer to a bowl.
  3. Add the melted butter and mix well.
  4. Press the biscuit mixture into the base of a 20cm quiche pan and
    refrigerate.
  5. In a medium bowl, whisk together sudachi juice, sweetened condensed milk, and egg yolks.
  6. Bake for 15-20 minutes, or until set.
  7. Remove from oven and let cool.
  8. Refrigerate for at least 2 hours before serving.
  9. Top with whipped cream.
Sudachi Ceviche
Ingredients:

  • 500 g fresh fish fillets, diced
  • 1/2 cup sudachi juice
  • 1/2 cup chopped tomatoes
  • 1/4 cup chopped red onion
  • 1/4 cup chopped cilantro
  • 1 jalapeño, seeded and minced
  • Salt and pepper to taste

Instructions:

  1. Combine diced fish and sudachi juice in a mixing bowl.
  2. Cover and refrigerate for at least 4 hours, or until fish is opaque and “cooked” by the citrus juice.
  3. Once the fish is ready, drain off excess juice and mix with tomatoes, red onion, cilantro, jalapeño, salt, and pepper.
  4. Serve chilled with tortilla chips or crackers.

 
Sudachi Glazed Salmon
Ingredients:

  • 4 salmon fillets
  • 1/4 cup sudachi juice
  • 1/4 cup soy sauce
  • 2 tbsp honey
  • 1 tbsp grated ginger
  • 1 tbsp minced garlic

Instructions:

  1. Preheat oven to 400°F (200°C).
  2. In a small saucepan, combine sudachi juice, soy sauce, honey, grated ginger, and minced garlic.
  3. Simmer over medium heat until slightly thickened, about 5 minutes.
  4. Place salmon fillets on a foil-lined baking sheet.
  5. Brush with the glaze and bake for 12-15 minutes, or until salmon is cooked through.
  6. Serve with rice, salad or steamed vegetables.
Sudachi Citrus Cooler
Ingredients:

  • 1/4 cup sudachi juice
  • 1/4 cup simple syrup
  • 1 cup soda water
  • Ice
  • Sudachi slices for garnish

Instructions:

  • Combine sudachi juice, simple syrup, and soda water in a glass.
  • Stir gently and garnish with sudachi slices.
Sudachi Citrus Sorbet
Ingredients:

  • 2 cups sudachi juice
  • 1 cup sugar
  • 1 cup water
  • 1 tbsp grated sudachi zest

Instructions:

  1. Combine sugar and water in a saucepan and heat over medium heat, stirring until sugar dissolves.
  2. Remove from heat and let cool.
  3. Once cooled, mix in sudachi juice and grated zest.
  4. Pour the mixture into an ice cream maker and follow the manufacturer’s instructions to freeze.
  5. Transfer to a lidded container and freeze until firm.
Sudachi Citrus and Soy Glazed Pork Chops
Ingredients:

  • 4 pork chops
  • 1/4 cup sudachi juice
  • 1/4 cup soy sauce
  • 2 tbsp honey
  • 1 tbsp minced garlic
  • 1 tbsp grated ginger

Instructions:

  • Combine sudachi juice, soy sauce, honey, minced garlic, and grated ginger in a saucepan and simmer over medium heat until slightly thickened, which should take about 5 minutes.
  • Preheat a grill or grill pan to medium-high heat.
  • Season pork chops with salt and pepper, and grill for about 4-5 minutes per side, or until cooked through.
  • During the last few minutes of cooking, brush the chops with the sudachi glaze.
  • Let rest for a few minutes before serving.

 

How to store sudachi

Store sudachi in a plastic bag in the crisper compartment of your fridge between 2 – 5°C. The skin may turn yellow, and the aroma and flavour may slightly decrease, however, this will have no impact on the taste. Sudachi can be juiced and stored in ice cube trays.

Where is sudachi grown?

Sudachi is primarily grown in Japan, particularly in the Tokushima prefecture on the island of Shikoku, where it is considered a specialty crop. Tokushima Prefecture accounts for approximately 98% of sudachi production, with Tokushima City, Kamiyama Town, Sanagochi Village and Anan City as the main producers. Sudachi is available year-round in Japan, outdoor grown sudachi flowers from May to June, and the fruit is harvested when unripe, between the months of August and November. Sudachi is also grown in large greenhouses to provide fruit year-round. Due to its delicate nature, the fruit is harvested by hand.

Sudachi is graded according to rind quality, blemishes and size. Grade A is the highest, followed by B and C. Some fruit is ‘ungraded’ which means it has not been graded. Greenhouse-grown sudachi (house sudachi) is said to have thinner skin and less aroma than sudachi grown outdoors (outdoor sudachi or roji sudachi). There are four sudachi sizes; L, 2L and 3L. L is the largest, and 3L the smallest, 2L is the most popular size.

Despite its popularity in Japan, sudachi is still relatively unknown outside of Japan and is considered a speciality fruit. However, it is slowly gaining the attention of chefs around the world. Currently, sudachi is cultivated in California, United States and Piura, Peru. Hopefully, this fruit will become more readily available outside Japan as interest and demand increase. 

Health benefits of sudachi

Not only does sudachi taste great, it also contains a number of important phytochemicals that are great for our health. Sudachi is is rich in ascorbic acid (vitamin C), essential for boosting the immune system and maintaining skin health. Antioxidants protect the body against cellular damage and reduce inflammation.

Sudachitin is a polymethoxyflavone (special flavonoids in citrus fruits) isolated from the peel of sudachi that has been found to induce apoptosis (programmed cell death) in HaCaT cells, which raises the potential to be developed into drugs to treat various skin diseases. Another study found sudachitin inhibited the proliferation of a wide range of tumour cells, including liver, cholangiocarcinoma, pancreatic and colorectal cancers.

Sudachi is a rich source of polyphenols, which are plant-based compounds that have antioxidant and anti-inflammatory properties. Polyphenols protect the body against cell damage caused by free radicals which can cause cancer, heart disease and Alzheimer’s disease. Several types of polyphenols are present in sudachi including flavonoids, coumarins and limonoids. Flavonoids are a group of polyphenols that have anti-inflammatory, anti-cancer and anti-diabetic properties. Coumarins have been shown to have anti-tumour and anti-inflammatory properties. Finally, limonoids have been found to have anti-cancer properties.

One study involving 40 adults found that powdered sudachi peel significantly reduced triglyceride levels, body weight and waist circumference in participants with levels over triglyceride levels over 120 mg/dl.

Where to buy sudachi

Sudachi fruit is still almost impossible to purchase outside Japan, however, specialist nurseries sometimes have grafted sudachi trees for sale. It typically takes an immature citrus tree 3-4 years before it begins to produce harvestable fruit. Before this, any developing fruit should be removed to allow the tree to focus its energy on growing and not fruit production.

How to grow sudachi

Position Sudachi likes a minimum of six hours of sunshine a day, in a sheltered position, away from strong winds.
Water Water deeply when the top 5 cm (2 inches) twice a week, or more in hot weather.
Soil Sudachi trees need well-draining soil with a pH range of 6.0 to 7. They like moist soil, rich in organic matter, but overly wet or waterlogged soil can cause root rot. Sand or loam soils are ideal for citrus, if the soil is too heavy, add compost and gypsum.
Fertilisation Feed your sudachi with a good quality slow-release citrus fertiliser three times a year at the start of spring, summer and autumn.
Mulch Apply a 5 cm layer of mulch around the drip line of the citrus to retain moisture and keep weeds away. Do not apply directly around the trunk to prevent collar rot.

 

Notes:

Sudachi grows in similar conditions to other citrus varieties. As a tropical plant, citrus grows best in temperate to tropical climates and is not frost-hardy. Sudachi can be grown in the ground or in containers that are a minimum of 40 cm wide. Bear in mind that citrus grown in pots will produce considerably less fruit than those grown in the ground.

Sudachi can grow in cooler climates but must be brought indoors or placed in a greenhouse during the cooler months as it is not frost-hardy.

As a shallow-rooted tree, sudachi doesn’t like other plants around the root ball. Therefore it is important to remove weeds as they appear and mulch well.

Sudachi trees are grafted onto rootstock, occasionally suckers will develop below the graft which should be cut off as they take up nutrients and water from the grafted portion (scion).