Are you familiar with coffee processing methods yet? If you want to know a few basics about coffee fermentation and the types of fermentation processes involved, read our blog on experimental fermentation.
We hope you gather all the knowledge of coffee you need to become an established coffee expert. We’d suggest you get yourself trained at our Barista Training Institute In Adelaide to get your hands-on experience in coffee making.
Why Do We Process Coffee?
The purpose of processing coffee is to remove the outer layer of the coffee fruit, de-pulp it completely and bring out the seed that is then washed, dried, stored and then sold.
The cherries have layers on top. This includes: outer skin pulp, pectin layer, parchment or silver skin which lasts behind the second layer which is surrounded by two beans. The Civet consumes these coffee cherries and excretes coffee beans that is used to make one of the world’s most expensive coffees – The Kopi Luwak coffee.
Its aim is to remove these layers, getting back to the essence of the product and drying it at optimum levels. Many attractive flavourful tastes are, however obtained from the fruits, juices, or pulp instead of the seeds themselves.
Local or intentional populations of yeast and bacteria will enter the fruit at the access point and begin to metabolize the sugars and acids inside the coffee fruit immediately, a process that can continue until the coffee is dried to the standard of 11% moisture.
What Is The Most Popular Coffee Processing Method?
The washed method is widely employed by coffee makers worldwide. This process consists of removing mucilage from beans and pulp using a machine. They’ll ferment in water for 12 – 36 hours, rinse in plenty of water then dry and remove parchment from the beans.
What Are The 3 Major Processing Methods?
The 3 major coffee processing methods include:
- The Washed Method
- The Natural Method
- The Honey Method
The Washed Method – Wet Process
Washed coffees are a staple of a number of countries, such as Brazil, Ethiopia, Indonesia and Yemen. All are well-known and well-respected for their coffee production. The washed process itself is also sometimes referred to as the “wet process” or “fully washed process”.
What Are The Steps Involved In Washed Coffee Processing?
- During the washing process, the whole fruit skin of beans is removed by machine before soaking the beans. It is possible to remove fruit flesh using an excavator or vacuum cleaner
- After de-pulping, they are put in water to allow fermentation and remove the remaining fruit flesh from the water
- The period for fermentation depends upon weather and altitude. In hotter locations fermentation can be done faster and vice-versa
- The fermentation usually takes 24 to 72 hours and is not beneficial to coffee’s flavour or aroma
- The coffee beans are now covered in mucilage and are set aside for further mucilage removal
- If the mucilage is left on, it will significantly alter the ultimate flavour of the bean because it is composed of a range of various sugars and alcohols
How Does Washed Coffee Taste?
When compared to natural coffees, many claim that washed coffees taste like white wine. The washing technique is favoured by many farmers and producers because, when done correctly, it lowers the possibility of faults and produces coffee that is more stable.
What Are The Steps Involved In Natural Coffee Processing?
Natural processing is also called the dry method that has been traditionally used to process coffee. Once the cherry is extracted from the cherries, it is spread in thin sections to cool down in the sunshine.
- In raised beds or on brick patios, drying is carried out in a manner similar to the washed method
- The beans are turned frequently in the natural process to ensure equal drying.
- Additionally, the beans can be mechanically dried, particularly in areas with insufficient sunshine or high humidity
- To prevent mould, fermentation and spoilage, cherries are rotated periodically
- After cherries have been thoroughly dried, the skin is removed by removing dried fruit skin and green coffee is stored before export
- Natural process coffees are often described to have red wine like flavours when compared to washed coffees
- Naturally process coffees can be useful for roasteries and baristas to showcase what coffee can taste like and appeal to open-minded consumers, but they won’t be suitable for those who don’t like fermented and wild flavours in the cup
The Honey Method – Pulped Natural Process
- The honey process involves selecting and sorting coffee cherries, removing the skins and pulps similarly with other varieties of coffee, and then drying the beans without removing the fruit’s sticky, sweet outer covering
- The honey production method is most widely employed in Central American countries, including Costa Rica and El Salvador. It is mechanically extracted but the de-pulper is set up for leaving a specified portion on the beans
- The soaked beans are then taken straight to an outdoor drying table for drying. As more beans are covered with skin it is easier to prevent excessive fermentation
- Honey processed coffee provides good characteristics from washed or natural coffee, the sweetness of natural products and brightness of washed coffee
What Does Honey Processed Coffee Taste Like?
Coffee connoisseurs have noticed that honey process coffee has a flavour profile that includes hints of cedarwood, chocolate, brown sugar, and spices.
How Long Does The Fermentation Process Take?
Normally, the fermentation process takes between 24 and 72 hours, and if the coffee beans are fermented for too long, the flavour of the coffee will suffer.
Such a process can take several hours or even many days, depending on the technique, washing station, environment, and many other elements.
Depending on the environment and altitude, fermentation takes a certain period of time. Fermentation will proceed more quickly in hotter climates and vice versa.
The coffee beans are washed to eliminate any remaining flesh once the fermentation is complete, and then they are ready to be dried. In brick patios, drying is carried out in a manner similar to that found in natural processes.
After being removed from the water, the coffee is dried in the sun or the shade. after wet processing, coffee beans are dried. Honey and natural pulp Both of these processing techniques are quite comparable to one another.
What Are The 4 Modern Coffee Processing Methods?
- Aerobic Fermentation
- Anaerobic Fermentation
- Lactic Process
- Carbonic Maceration
- Aerobic Fermentation: The only variables that are kept track of during aerobic fermentation are time and temperature. Freshly picked cherries are collected and placed in a tank with water that is exposed to the air for 16 to 20 hours, during which time they quickly decompose.
Close observation is necessary because the coffee is more exposed to the weather. The sugar-rich cherries attract atmospheric bacteria and yeasts, which can become out of control if not properly controlled.
This or a sharp rise in the exothermic heat produced by the breakdown might produce flavours resembling vinegar.
- Anaerobic fermentation: This method is gaining popularity in Costa Rica and all of Central America. The coffee cherry is put on a de-pulper and the separated seed is placed within fermenting containers that are airtight.In certain situations, pulps are included separately. After that, the tank must be closed and the oxygen turned off.
It may take 20 hours to complete this process. Due to the carbon dioxide produced during fermentation, the water pressure rises during this period.We carefully measured the sugar concentration, temperature, and pH levels. Before the fermentations may continue and produce alcohol, the reactions must halt.
- The Lactic process (processing with lactic acid bacteria): A coffee producer will choose cherries that are fully ripe and have the largest sugar content feasible for a lactic fermentation, then place those cherries in an anaerobic setting like a tank or sealed barrel.The producer will closely monitor and regulate temperature, pH levels, and oxygen availability throughout the subsequent fermentation process to provide the ideal circumstances for lactobacillus to thrive and take control of the fermentation.You may hear the term “lactic fermentation” used in conjunction with other processing techniques, such as “Lactic Washed,” which indicates that the coffee was pulped (to remove the cherry skin and fruit) before it was lactic fermented and then dried, or “Lactic Natural,” which indicates that the coffee was lactic fermented and dried with the cherry skin and fruit still intact. Lactic fermentation can be used for whole cherries or pulped beans.
- Carbonic Maceration: Carbonic maceration is a fermentation technology that was initially popularised in the coffee industry in 2015 and was adapted from the manufacturing of wine.Barista champion Sasa Sestic invented carbonic maceration when he employed it for a coffee that won the Barista Championship in order to produce a coffee with more aromatic complexity and a low concentration of acetic acid.After learning about its application in wine, “esti” created the method with the help of Colombian farmer Camilo Merizalde. In order to ferment the grapes without rupturing their skins and allow the fermentation to take place inside each grape individually, carbonic maceration in wine employs an injection of carbon dioxide (CO2). Rather than being triggered by yeast, the initial fermentation happens intracellularly, or from the inside out.
Harmful Effects Of Coffee Processing Industry Wastewater
Wet processing systems typically produce huge amounts of dirty effluent that can be easily dumped into a nearby stream or river since they utilise a lot of water. The by-products from the processing of coffee include pulp (43%), mucilage (12%), and parchment (6.1%).
According to Navitha and Kousar (2018) and Sahana et al. (2018), this effluent typically contains a high concentration of organic waste and suspended solids and is also very acidic. Wet coffee processing also has a significant water use issue because it takes 15-20 L of water to process 1 kg of coffee beans; if water is not recycled, then the resources themselves are at risk (Dadi et al. 2018).
Additionally, the effluent from coffee processing facilities is coloured and contains various macromolecules like polyphenols (for example, melanoidins) and caffeine. The classes of ligands that make up coffee melanoidins include polysaccharides, tannins, and mixtures of these (Cardenas et al. 2009).
Its dark brown colour is caused by these macromolecules, which are difficult to break down using typical biological treatment methods (Péerez et al. 2007). As a result, the pollution brought on by the discharge of coloured effluent is to blame for its opaqueness, high chemical and biological oxygen demand, eutrophication, and light-blocking and photosynthesis-altering effects (Takashina et al. 2018; Tokumura et al. 2008; Péerez et al. 2007).
Wastewater Treatment Works For The Coffee Processing Industry
In order to reduce wastewater pollution in coffee processing plants, the coffee production and processing industries must implement wastewater treatment technologies. The commonly used wastewater treatment processes for coffee processing are as follows:
Biological Wastewater Handling
As the next step in the wastewater treatment system the biological settling tank also has the ability to filter the suspended materials in wastewater using gravity to settle into the tank to enhance wastewater treatment efficacy.
The tank is a common use in commercial water systems. When wastewater is stored in this tank, the waste can move on to another stage.
The sludge is placed in this tank, where a UASB tank will transfer into the sludge tank for treatment outside (squeeze sludge before removing it).
Treating Chemicals In Wastewater
Chemical substances like alum, oxidants and flocculants could be used for the wastewater treatment. These chemical substances can treat the wastewater by removing pollutants and enabling the wastewater to reach safe levels before getting released into the environment.
This stage helps get rid of solids and suspended matter by using clarifiers, dosing tanks, presses and filters. The stage gets rid of solids, suspended solids and residues in the wastewater that minimizes the impact on the environment.
It all boils down to personal preference when deciding between washed coffee processing and natural coffee processing. Washed coffee processing can be the best option if you want a more pristine, vibrant cup of coffee. Natural coffee processing can be the better option if you prefer a more nuanced, fruity flavour profile. Whichever method you choose, it will result in great coffee that will satisfy the palate of any coffee enthusiast.