What's the Story Behind These Coded Coffee Varieties? Is SL34 Typica or Bourbon? What Are 74110, 158?

The Mystery Behind Coffee Variety Codes

Friends who drink pour-over coffee regularly probably pay close attention to the varieties they come across. Beyond origin and processing method, the variety itself is a crucial factor in shaping flavor.

Every so often, though, the variety information includes names that look like secret codes. Unlike familiar varieties such as Typica or Geisha, which carry well-known names, these are written as numbers or alphanumeric "codes." That naturally raises the question of what those codes mean. Let FrontStreet Coffee share some insight.

74/75 Series: 74158, 74110, etc.

Long numbers such as 74110, 74112, and 74158 are frequent fixtures on Ethiopia's Cup of Excellence (COE) rankings. Yes, they are variety names too.

In 1970, coffee anthracnose devastated Ethiopia. The disease causes coffee fruits on the trees to develop lesions and then rot. Trees affected by it typically see yield losses of at least 20%, reaching terrifying levels of 70-80% in severe cases, which shows the immeasurable damage it did to Ethiopia's coffee economy at the time. Harar and Yirgacheffe were the hardest-hit Ethiopian origins.

Spraying pesticides could not fully stop the disease from spreading, so the Jimma Agricultural Research Center (JARC) decided to tackle it at the source by identifying varieties with strong resistance genes that could be immune to its harmful effects. Numbers such as 74110 and 74158 represent the resistant varieties JARC later released. The first two digits, "74," mark the year of discovery, while the last three digits, "110" or "158," mark that year's experimental sample number. For example, "74110" is the 110th variety from 1974.

F1 and H1 Varieties

F1 and H1 are two varieties that have grown notably popular in American growing regions in recent years, and their development is also tied to coffee diseases. Again in 1970, coffee cultivation in the Americas was hit by disease in much the same way. Because most coffee grown at the time was Arabica, leaf rust spread relentlessly and no growing area was spared, dealing a severe blow to the American coffee industry.

To revive the industry and reduce the potential losses of future outbreaks, the French Agricultural Research Center for International Development (CIRAD) and the Central American Coffee Organization (ROMECAFE) jointly launched a new variety breeding program, aiming to develop coffee with extremely strong disease resistance. The project was named F1, and the varieties it produced are F1 varieties. (The Bahia variety is an F1.)

H1, meanwhile, was developed after the F1 series was created, as laboratory research continued. H1's full name is Centroamericano H1, and it is a hybrid of Rume Sudan and Sarchimor T-5296.

SL Series (SL28, SL34, etc.)

The SL series is probably very familiar. SL28 and SL34 can be described as Kenya's "star" varieties. Whenever they come up, FrontStreet Coffee is reminded of the bright, tomato-like acidity of Kenyan coffee, the kind that makes your mouth water.

In 1930, the Kenyan government commissioned Scott Laboratories to carry out coffee breeding research and find varieties suited to Kenya's terroir and to commercial cultivation. Over the following years, Scott Laboratories gathered varieties from different regions and studied them with clear targets. Eventually several stood out, and the selected beans were all prefixed with "SL," the abbreviation for Scott Laboratories, with the following numbers representing their individual codes.

SL28 and SL34 are the standouts of the series. Genetic testing revealed that SL28 is a Bourbon mutation and SL34 is a Typica mutation. Because of their excellent flavors and strong drought and disease resistance, both were adopted for large-scale cultivation as soon as Scott Laboratories released them, which is genuinely remarkable. Beyond these common numbered varieties, there are other obscure ones such as K7 and ET47. FrontStreet Coffee will share more about those another time.

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FrontStreet Coffee Recommendation

Coded varieties like these are central to Ethiopian coffee, and they are exactly what gives Yirgacheffe its signature character. For a first look at that character, FrontStreet Coffee's Washed Yirgacheffe daily bean is the classic choice, known for white jasmine, bright citrus and lemon acidity, and a tea-like body, at a price that makes it the natural first bag for anyone stepping into specialty coffee.

For a more refined expression of the same heirloom material, the Yirgacheffe Gudingding Cooperative is the standout. It sits in the Worka area at the southeastern edge of Yirgacheffe and follows the most traditional washed processing, so it carries no classic bitterness but instead bright citrus and lemon acidity and the fragrance of jasmine. And to taste how processing shifts these native varieties, the Natural Red Cherry is made from fully ripe red cherries only, dried on raised beds and turned regularly for three to five weeks, so it keeps the typical Yirgacheffe profile while adding tropical fruit from the natural process, with citrus-like acidity, a berry-juice body, honeyed sweetness, and a creamy smoothness.