What Makes Yeast-Processed Red Label Geisha Coffee Beans Special? How Much Does a Cup of Red Label Geisha Coffee Cost?

The Art of Coffee Fermentation

In daily life the word "fermentation" often brings to mind dough for flatbreads or fried dough sticks, or thoughts of spoiled and moldy food. It has found so many uses that it has become ordinary: we enjoy fermented foods of every kind, from French wine to homemade pickles and Swedish surstromming. Everyone knows these come from fermentation.

In English, "fermentation" derives from the Latin "fervere," originally meaning "to boil" or "to bubble." It describes the phenomenon when yeast acts on grape juice or wort, creating a gentle foaming or an intense activity resembling a boil.

Beer Fermentation

Beer is unquestionably made through fermentation. The best-known fermentation reaction in alcoholic drinks is sugar producing alcohol and carbon dioxide through the action of yeast. But beer fermentation is far more complex than just making alcohol. Many flavors, pleasant and unpleasant alike, require precise human control over the fermentation environment and conditions so that the good ones are maximized and the bad ones minimized.

Whether making dough or brewing alcohol, both processes rely on the life activity of microorganisms under aerobic or anaerobic conditions, whether to prepare the microorganisms themselves or their direct and secondary metabolites.

Interestingly, during beer fermentation the yeast stays hungry in the later stages. By then the fermentable sugars may be exhausted, and the various fermentation by-products become food for the yeast.

This is where brewers control the process so that more unpleasant flavors are consumed and fewer pleasant ones are eaten - shifting from addition to subtraction. It is also why red wine often tastes better with age: unpleasant flavors diminish and the wine becomes clearer and cleaner.

Coffee Fermentation

Different biological changes occur during coffee's natural fermentation. Yeast produces enzymes, and lactic acid bacteria break down the sugars in the coffee pectin. Lipids, proteins and acids in the sugars degrade and transform. The coffee's aroma, color and pH change, and the makeup of the pectin shifts as well.

The core of any processing method lies in fermentation. During fermentation, different participants (coffee skin, pulp, pectin, the types and distribution of microbes), different environments (with or without water, aerobic or anaerobic, the pH), and different drying methods (container material, sun drying, drying equipment, turning frequency) together create different post-processing flavors and textures.

The basic coffee chain runs from cultivation to green-bean processing to roasting to brewing. At the green-bean stage, however, every processing method is inseparable from fermentation.

We commonly see dry and wet fermentation, but how do the recently popular anaerobic and yeast processing methods work?

Yeast Processing Method

From any angle, adding yeast during fermentation is a bold approach.

In 2017 in Gothenburg, Sweden, French biology PhD Camille Delebeque gave a presentation at Re;co. His company controls microorganisms during coffee fermentation to change coffee flavor, making coffee less bitter, less astringent and sometimes even less acidic. He calls the product "cultured coffee" or "microbial coffee."

Their approach selects specific yeasts or microorganisms for a so-called secondary fermentation to enhance good flavors or reduce unwanted ones. Although he revealed neither which microorganisms he used nor how the secondary fermentation works, and gave no information about origin or variety, his pricing was anything but cheap: 5 ounces (148 g) for $29.

El Salvador's most renowned coffee farmer, Aida Batlle, collaborated with the American roaster Equator to test yeast's effect on flavor by adding yeast to the fermentation tanks for Bourbon beans from the Buenos Aires farm in El Salvador, comparing the results with a traditional washed process without yeast. In 2017 they experimented with two different yeasts and found that each produced different results: one increased sweetness, balance and consistency, while the other enhanced brightness and fruit. Yeast processing added flavors that traditional washed processing rarely achieves - sugarcane, lemon, nutmeg and sage.

According to official information, this year's Panama Geisha estate auction yeast-processing series (ES-Y) consists of four lots and nine boxes of Geisha beans with unique flavors, processed with the new "yeast fermentation method."

One of the biggest highlights of the auction was the addition of the yeast-processing lots: fermented in tanks with special yeast for 48 hours before washing, then dried on beds for 4 days. Adding yeast during post-processing makes the fermentation faster and more thorough while creating special flavors.

Different wine-like characteristics emerge depending on the yeast used. Compared with yeast B, yeast A shows more obvious red wine flavors, and its red wine character is more refined, presenting the Geisha qualities more beautifully, which is why Y-1 is more expensive.

Lot ES-Y-1: processing method - yeast A added, fermented for 48 hours, then washed, followed by 4 days of drying on racks. Auction price: $340 per pound.

Lot ES-Y-2: processing method - yeast B added, fermented for 48 hours, then washed, followed by 4 days of drying on racks. Auction price: $111 per pound.

According to estate manager Rachel Peterson, this yeast fermentation method represents the estate's experiment with processing, to observe how Geisha beans perform after yeast-inoculated fermentation.

Processing: fully ripe red fruits are hand-picked, undersized beans are screened out, and after water floatation selection the cherries are soaked in clean water. Fermentation lasts about 48 hours with yeast added, followed by sun drying. The cherries are spread in one to two layers on sun-drying beds for 4 days of exposure, at an average daily temperature of 16-23°C and a nightly temperature of 10-15°C, achieving a completely different, unique flavor.

After cupping the yeast-processed Red Label, we were delighted to find that the method enhanced Geisha's performance across the board - aroma, body, acidity and aftertaste - and that it is quite different from naturally processed Geisha. Overall it sits closer to anaerobic fermentation: it produces excellent Geisha in terms of aroma and flavor, smooths out the harshness and excessive acidity of washed coffee, brings balance and rich layers, and adds red-wine-like flavors.

FrontStreet Coffee Recommendation

For anyone drawn to the yeast-processed lots, the natural reference point is Esmeralda Red Label Geisha. FrontStreet Coffee's Red Label, formally "Esmeralda Special," is grown at 1600-1800 meters, and every lot is cupped above 90 points, each carrying its own lot number and coming from a single small plot - FrontStreet's own Red Label comes from the Jaramillo block, which lets drinkers compare the fine differences between closely related lots.

Yeast inoculation tends to push Geisha toward darker, wine-like fruit and a rounder structure, so it is worth tasting alongside a more conventional representation of the same estate. Esmeralda Green Label Geisha, originally "Private Collection," blends lots from several plots to express the estate's signature high-altitude Geisha character without emphasizing individual plot detail, which keeps it more affordable and makes it an excellent value. FrontStreet Coffee also keeps Panama Boquete Geisha, an entry-level Geisha that brings out the classic Panamanian orange-blossom-honey note, an oolong-tea sensation and a fine, layered fruit acidity at a friendly price for readers who simply want to see what the estate's name is all about.