Maesil-ju (Korean: 매실주; Hanja: 梅實酒), also called plum wine, plum liquor, or plum liqueur, is an alcoholic drink infused with maesil (plums).The exact origins of Maesil-ju are unknown, but it is thought to date back to the Goryeo Dynasty (918-1392)^[1].^[2][3][4][5]

Maesil-ju is made with maesil (매실; 梅實; "plums"), preferably ripe hwangmae (황매; 黃梅; "yellow plums"), which are yellowish in color, fragrant and firm.^[6][7][8] Unripe cheongmae (청매; 靑梅; "green plums")—firmer and less fragrant—can also be used.^[8][9] Bruised or over-ripened plums may make the wine cloudy.^[8] Damaged fruits should be avoided, as direct contact of plum seeds with alcohol may produce a small amount of prussic acid, due to the amygdalin in plum seeds.^[10] However, toxicity vanishes after a year of maturation.^[10] Ripe plums have much lower amygdalin content.^{[citation needed]}

Typically, 3 litres (0.66 imp gal; 0.79 US gal) of soju (of 20% ABV) and 100–150 grams (3.5–5.3 oz) of sugar is used per 1 kilogram (2.2 lb) of plums.^[8] Sugar can be substituted with slightly more honey, and soju of 20% ABV can be substituted by 2 litres (0.44 imp gal; 0.53 US gal) soju (or any other unflavored spirit) of 30% ABV and 1 litre (0.22 imp gal; 0.26 US gal) of water.^[8]

Plums are washed in cold water and dried on a tray for a day.^[8] Dried plums and soju are added to a sterilized glass or earthenware jug and infused for about 100 days.^[8] The fruits are then removed by sieving, and sugar is added to the plum wine.^[8] The wine can be consumed immediately, but three to six months of maturation will greatly enrich the wine's flavour.^[8]

Popular maesil-ju products include Mae hwa soo,^[11] Matchsoon,^[12] and Seoljungmae.^[13]

• Maesil-cha, plum tea
• Maesil-cheong, plum syrup
• Umeshu, Japanese plum liqueur
• Suanmeitang, Chinese plum beverage