[Gu Eun-mo's Sake Story] Capturing the Full Aroma of Yeoju Sweet Potato in Distilled Soju

<3> Gyeonggi Yeoju 'Kooksoondang Yeoju Myeongju'①

Grown in sandy soil with high starch content, ideal for brewing
Kooksoondang, Yeoju City, and sweet potato farmers unite to restore traditional liquor culture
Brewed with fresh sweet potatoes with less off-flavor, featuring rich aroma through low-pressure distillation
Softness and depth enhanced through traditional earthenware aging

Front View of Kooksoondang Yeoju Myeongju Distillery

[Asia Economy Reporter Eunmo Koo] During the Joseon Dynasty under King Yeongjo, the Silhak scholar Lee Jung-hwan mentioned several riverside villages as ideal places to live in his geographical book "Taekriji (擇里志)." Among them were Pyongyang by the Daedong River, Chuncheon by the Soyang River, and Yeoju in Gyeonggi Province, where the Namhan River flows through the Yeo River basin. Although the surrounding mountains of Yeoju are rugged, the interior consists of gently spreading plains, with the Namhan River running through its center. The fertile land receives ample sunlight without obstruction, making it undeniably a desirable place to live. It is also widely known that the Joseon royal family cultivated purple-colored rice called Jachae (紫彩) here under direct royal management.

These excellent natural conditions are not limited to rice farming; a prime example is sweet potatoes. Along the Namhan River in Yeoju, sandy soil spreads widely, making it suitable for cultivating high-quality sweet potatoes. Sweet potatoes grown in well-drained sandy soil in Yeoju have good coloration and dense flesh, and especially due to the large temperature difference between day and night during the harvest season in August and September, they have a high starch content. Although sweet potatoes grow well in any region of the Korean Peninsula, this is why Yeoju’s sweet potatoes are recognized for their superior quality.

Sweet potatoes are generally divided into two types: chestnut sweet potatoes and watery sweet potatoes. Chestnut sweet potatoes have less moisture and a dry, mealy texture, while watery sweet potatoes contain more moisture and have a softer, mushy texture. Typically, those with a starch content of 23?25% are classified as chestnut sweet potatoes, and those with 18?19% as watery sweet potatoes. Chestnut sweet potatoes, with their higher starch content, have a higher alcohol conversion rate and richer aroma when fermented for alcohol production.

'Goguma Distilled Soju Rye' Made from Top-Grade Yeoju Sweet Potatoes with High Starch Content

The sprouting of 'Kooksoondang Yeoju Myeongju' was precisely due to these characteristics of Yeoju sweet potatoes. Yeoju City and local sweet potato farmers proposed a traditional liquor project using sweet potatoes to Kooksoondang to expand the market for their carefully cultivated sweet potatoes. This proposal aligned perfectly with Kooksoondang’s goal to restore regional traditional liquor culture by developing alcoholic beverages using local specialties and to establish a win-win management model with rural communities, leading to concrete plans.

Thus, Yeoju City and sweet potato farmers provided the raw sweet potatoes, while Kooksoondang took charge of product development, marketing, and distribution. In April 2011, they jointly invested to establish the agricultural corporation Kooksoondang Yeoju Myeongju. Subsequently, Yeoju Myeongju built a distillery in Gangcheon-myeon, Yeoju City in 2012, began full-scale distillation in 2013, and in September 2016, launched its first product, the sweet potato distilled soju 'Ryeo (驪)'.

'Ryeo' derives its name from Yeoju (驪州), where Yeoju Myeongju is based, and from Goryeo (高麗), where distilled soju was first produced on the Korean Peninsula. The character 'Ryeo' in Yeoju means 'black horse,' and to express the stronger aroma and flavor of sweet potato soju compared to rice soju, the product label features a black horse symbolizing strength.

The image shows sweet potatoes, the raw material for sweet potato distilled liquor, being taken out after steaming.

Good Distilled Liquor Must Fully Embrace the Characteristics of Raw Materials

Park Yong-gu, CEO of Kooksoondang Yeoju Myeongju, emphasized that good distilled liquor should capture the characteristics of the raw materials well and possess distinctiveness based on the region and technology, along with diverse flavor personalities. He said, “Unlike traditional distilled soju centered on rice, Yeoju Myeongju uses sweet potatoes, a material that clearly reflects the characteristics of the Yeoju region, and through excellent methods and aging, produces liquor with depth and elegance. Our goal is to contribute to expanding the distilled soju market through Ryeo.”

Sweet potato distilled soju Ryeo is made exclusively from sweet potatoes. The sweet potatoes used are carefully selected from freshly harvested crops in the fields of 24 farmers who participated in establishing the company, choosing only those without damage. To eliminate off-flavors and maximize the unique aroma of sweet potatoes, only fresh products harvested within seven days are used. CEO Park explained, “The sweet potatoes we usually eat undergo a curing storage process to increase sweetness. While this makes them tasty when steamed, it reduces aroma when used for alcohol production. Therefore, only freshly harvested sweet potatoes are used here.”

The selected sweet potatoes have their two ends, which contain many fibers and cause bitterness, manually trimmed by 2?3 cm to use only the high-quality central parts, further enhancing the liquor’s aroma. After preparation, the sweet potatoes are washed, steamed in 500 kg batches, cooled to about 25°C, and then crushed with a grinder. The crushed sweet potatoes are transferred to a 3,000-liter fermentation tank for stirring, then moved to a 15,000-liter storage tank where fermentation occurs with yeast over a set period.

After fermentation, the mash is piped to a 5-ton brass distiller. Ryeo uses atmospheric distillation, which occurs at normal atmospheric pressure (1 atm), allowing various aromatic compounds to distill together, resulting in a rich aroma. In contrast, vacuum distillation, performed at lower pressure and temperature, produces a smoother product.

The distilled raw liquor is placed in traditional earthenware jars fired without glaze to allow the liquor to breathe during aging. Aging in these jars softens the harsh alcohol taste and deepens the sweet and fragrant flavors unique to sweet potatoes, maturing the liquor. Only after enduring more than 18 months of aging is the liquor finally released to the market. CEO Park stated, “Good distilled soju undergoes aging over time rather than relying on additives or shortcuts to achieve smoothness and harmonious flavor. Anyone who tastes aged distilled soju can clearly recognize that the longer it matures, the more valuable it becomes.”

Onggi jars inside the Guksundang Yeoju Myeongju aging room.

This content was produced with the assistance of AI translation services.