How To Properly Ferment Coffee And Ensure Quality? Which variables should coffee growers consider in order to control fermentation and assure consistent quality? A detailed explanation of the coffee fermentation process is provided below to assist you in answering the above question and understanding the process in the most professional manner possible to aid you in controlling the quality and consistency of batches.
1. Excellent Cherry
The harvest’s quality is critical. “The quality of the raw material or cherries is fundamental.” Because of their diverse metabolic processes, yeast [in fermentation] can only work with what is available to disclose or enhance certain scent components.
Minerals, nitrogen, and amino acids are required by plants. The only way to offer this is to have a health plan that reduces stress and [creates] better circumstances for the cherry to grow and flourish.
So, in order to have a healthy cherry, you must apply everything in the field, including nutrition, pest and disease control, and the quantity of water, shade, and pruning.
Microorganisms are omnipresent, yet not all of them are beneficial to your coffee. Coffee cherries “already contain microorganisms clinging to their surface, as well as the soil, harvesting materials, workers’ hands, and transportation, reception, and processing equipment.” These may result in pollution.
While it is difficult to maintain a microorganism-free farm or mill, hygiene may go a long way toward helping. After usage, washing tanks should be cleaned. So, too, should all of the tools that are employed.
Fermentation may be classified into two types: aerobic and anaerobic.
The presence of oxygen in aerobic fermentation adds to the respiration and development of bacteria. Aerobic fermentation is the most often utilized method. Nonetheless, that is a fermentation process over which you have little influence.
This is due to the presence of microbes everywhere, and oxygen influences their development in unpredictable and difficult-to-control ways.
In anaerobic fermentation, the coffee is often put in a closed tank with no oxygen present and a carbon dioxide release valve. This provides manufacturers more control over the chemical processes that are taking place.
4. Type of Microorganism and Yeast
Different yeasts and bacteria will have varying impacts on the fermentation process, as will the pH of the solution. For example, the yeast Saccharomyces cerevisiae is used in the production of all of their goods.
The yeast, however, can have a significant influence on the coffee depending on the strain: one can “significantly improve the fruity flavor (apricot, passion fruit, floral notes, vanilla), the mouthfeel of the coffee, and the final cup quality;” the other, the “brightness and citrus notes… the mid-palate mouthfeel;” and a third, “is often preferred when processing time and efficiency is a primary concern.” The strains are listed below.
During the fermentation process, the introduced yeasts were able to outcompete the indigenous or native microorganisms, resulting in a better-regulated fermentation process.
It is possible to produce greater consistency and cleaner cup profiles when you employ microorganisms in a population where you saturate the fermentation tank, as opposed to when you ferment with random processes and have no way of knowing what is truly affecting the fermentation.
5. Temperature & Time
These two variables are crucial since the temperature has an effect on fermentation pace. When the fermentation process occurs inside the bean at a temperature of less than 20oC, we may extend the fermentation time to 36 hours.
On the other side, at higher temperatures, fermentation occurs more rapidly — often too rapidly. It is likely that within 24 hours, we will have issues that manifest themselves as faults in the cup.
6. Data & Records
Without documentation of data and procedures, it becomes more difficult to adhere to the same norms in the future. Each piece of data is valuable, from the harvest season’s temperature to the time of day the coffee was gathered and the duration of the fermenting process.
Make careful to check the pH level of your coffee, which indicates how acidic it is. Keep track of your Brix levels, which indicate not only the quantity of sugar in your coffee but also the amount of substrate or food consumed by bacteria and yeasts.
Without data or a processor, we don’t know the context, and we don’t have a method to repeat it… Thus, in order to achieve repeatability, it is unavoidable that you monitor and understand how variables react throughout the process.
And you absolutely must understand the temperature flux or behavior throughout fermentation, the dynamic of the Brix levels during fermentation, and the dynamic of the acidity on the mucilage during fermentation, since you may make judgments or even terminate the process based on this information.
EACH COFFEE IS UNIQUE
However, keep in mind that although these six variables are critical for consistent, high-quality coffee, they cannot be applied uniformly to every batch.
There are several variations with which you may experiment with various fermentation processes, whether long or short, at higher or lower temperatures, with or without the inclusion of microorganisms.
As a result, become well-versed in coffee. Consider the variety you have and the tastes they typically have. Additionally, ensure that you are familiar with your farm, from the soil to the local climate.
The critical nature of knowing which kind of processing works best in your location. If you operate in a humidor chilly climate, natural or dry processing may not be the best option. On the other hand, if you live in a dry place with plenty of sunshine and low humidity, you may manipulate the drying process.
You must understand how bacteria will react in response to these environmental variables, keeping in mind that fermentation begins in the crop and ends throughout the drying process.
Fermentation is a poorly known issue, yet it may have a much too substantial influence on coffee quality to overlook. We must overcome our fear and begin experimenting in order to get greater outcomes and features in our coffee.
This is a symptom of the crisis we are experiencing. “One thing that may save us is ensuring that our goods are consistent and thereby enhancing their quality via more regulated procedures across the manufacturing chain.”
After all, why is consistency necessary? To assign a monetary value to the output. To reduce the quantity of low-cost commercial coffees and raise the number of specialty coffees, as well as to expand into new markets.