In the coffee world, fermentation processes contribute significantly to the flavor profile of coffee. In recent years, the "lactic fermentation" method in particular has attracted great interest among coffee producers and consumers. So how does lactic fermentation affect coffee? Under what conditions should it be applied? In this article, we will examine the effects of lactic fermentation on coffee, its application methods, and points to consider.
What is Lactic Fermentation?
Lactic acid fermentation is a biochemical process in which certain bacteria convert glucose into lactic acid in an anaerobic (oxygen-free) environment. These bacteria include species such as Lactobacillus and Pediococcus .
This process is particularly used in food production and is commonly seen in the preparation of products such as yogurt, pickles and sourdough bread. In coffee fermentation, the inclusion of lactic acid bacteria in the fermentation process can affect the coffee's characteristics such as sweetness, body and fruity aroma.
Stages of Lactic Fermentation
The lactic fermentation process allows coffee beans to go through certain stages to reach the desired flavor profile. Here is the lactic fermentation process step by step:
Step 1: Harvesting Coffee Cherries
For lactic fermentation to be successful, only fully ripe, top quality coffee cherries should be collected.
Harvesting can be done by hand or mechanical methods, but hand-harvested coffees offer a more uniform quality.
Stage 2: Pre-Selection and Cleaning
The harvested coffee cherries are placed in water tanks and the defective fruits remaining on the surface are separated.
Cleaning the coffee fruit from foreign substances ensures that the fermentation process can be controlled.
Stage 3: Controlled Fermentation
Coffee cherries are placed in fermentation tanks either whole or peeled.
The duration of the fermentation process can generally vary between 24-96 hours .
Control of the process can be achieved by adding lactic acid bacteria (LAB) .
Temperature and oxygen levels should be carefully monitored during fermentation. An oxygen-free environment is provided to prevent the formation of unwanted microorganisms.
Step 4: Supporting Fermentation with the Use of Salt
Fermentation experts like Lucia Solis recommend adding low amounts of salt to fermentation tanks.
Salt limits the growth of harmful bacteria while encouraging lactic acid bacteria to become dominant.
Stage 5: Completion of Fermentation and Drying
Once fermentation is complete, the coffee beans are washed and the remaining mucilage is removed.
The drying process is critical to balancing the coffee’s flavors. During this stage, the beans are usually dried on raised drying beds or concrete floors .
Drying time can vary between 15-30 days and the coffee beans are turned regularly to ensure homogeneous drying.
Stage 6: Resting and Storage
Once drying is complete, the coffee beans are left to rest in a cool, dry environment for 45 to 60 days .
This stage allows the flavors that develop after fermentation to settle and the coffee to reach a more balanced profile.
Effects of Lactic Fermentation on Coffee Flavor
Lactic fermentation contributes significantly to the flavor profile of coffee. This process can affect the following flavor components:
Sweetness: Lactic acid bacteria optimize the sweetness balance of coffee by converting sugars into lactic acid during the fermentation process.
Balance and Body: Lactic acid makes the body of the coffee creamy, providing a smoother drink.
Fruity and Complex Aromas: Esters and organic compounds formed during fermentation help tropical fruit, red fruit and citrus notes to stand out.
Acidity: Offers a lower and more balanced acidity profile compared to the washed processing method.
However, the fermentation time and conditions must be carefully controlled, otherwise unwanted vinegar or over-fermentation symptoms may appear in the coffee.
Lactic Fermentation and Comparison with Other Processing Methods
Let's take a look at the table below to see how lactic fermentation ranks among different coffee processing methods:
Processing Method | Sweetness | Acidity | Body | Fruity Aroma |
Washed Processing | Middle | High | Light | Middle |
Natural Processing | High | Middle | Busy | High |
Honey Processing | Medium-High | Middle | Balanced | Balanced |
Lactic Fermentation | Very High | Low-Medium | Creamy | Complex and Intense |
Leading Coffee Farms Producing Lactic Fermentation in the World
Lactic fermentation has been adopted and experimentally developed by many innovative coffee farms around the world. Here are some of the most prominent farms in this field:
Finca Deborah (Panama): Famous for its Panama Geisha coffees, this farm uses special lactic fermentation methods to give the coffee a unique complexity to its flavor profile.
El Vergel (Colombia): Known for its innovative fermentation processes, El Vergel is one of the producers that receives high marks for its lactic fermentation-processed coffees.
La Palma y El Tucan (Colombia): Known for its experimental processing techniques, this farm produces coffees with fruity and creamy bodies by precisely managing the lactic fermentation process.
Daterra (Brazil): Attaching importance to sustainable agricultural practices, Daterra is among the producers that develop different taste profiles with controlled fermentation processes.
Finca El Paraiso (Colombia): A farm that makes a difference in the coffee world with its experimental processes combining thermal shock and lactic fermentation.
These farms offer new taste experiences in the world of coffee by developing lactic fermentation processes at an advanced level.
Criticisms and Bad Practices of Lactic Fermentation
Although lactic fermentation is thought to give complex flavors to coffee, incorrect applications can negatively affect quality. Here are some points criticized by coffee experts:
Excessive Fermentation: Uncontrolled, prolonged fermentation can lead to overly acidic flavors and off-flavors.
Inadequate Hygiene Conditions: Failure to sterilize fermentation tanks may lead to the development of undesirable bacterial species.
Inadequate Control of Oxygen Levels: Extremely anaerobic environments can lead to unpleasant fermentation odors in coffee beans.
Excessive Use of Salt: Using salt above controlled levels can mask the natural flavors of the coffee, leaving unwanted salty notes.
Over-commercialization of the Market: Some manufacturers over-emphasize the process and exceed standard fermentation times, using lactic fermentation solely as a marketing strategy.
For these reasons, lactic fermentation must be applied correctly and based on scientific principles.
Lactic fermentation stands out as an innovative and effective method in coffee processing processes. When applied correctly, it enriches the flavor profile of the coffee and offers consumers a unique experience. While this method provides coffee lovers with a different taste experience in terms of sweetness and fruity aromas, producers need to carefully manage the fermentation process. There is no doubt that it will negatively affect the quality of the existing coffee in the other stages.
D.EMRE KURTULUS