What is the Red Wine Processing Method in Coffee | Is Red Wine Added to Coffee with Red Wine Processing?

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Introduction to Red Wine Processing Method

When it comes to coffee processing methods, we typically think of washed, natural, honey, and wet-hulled processes. Today, FrontStreet Coffee would like to introduce you to the red wine processing method!

Coffee and red wine—have you ever considered their relationship? While traditional coffee processing techniques may be familiar to many, how much do you know about coffee processed using red wine methods?

In 2015, WBC competitor Sasa introduced to the world a Colombian coffee bean processed through a method similar to red wine fermentation. Beyond the novel taste of the beans, the "red wine processing method" used to treat them sparked immense curiosity among coffee enthusiasts, including ourselves. So what exactly is this so-called "red wine processing method"?

Understanding the Red Wine Processing Method

Although specific details of the red wine processing method remain largely unknown, we have combined the aforementioned information with our understanding of wine fermentation processes to roughly outline the procedure of this "red wine processing method."

The red wine processing method for coffee beans, also known as wine-like processing, draws inspiration from red wine fermentation techniques. Currently, only eight estates in Colombia have successfully brought coffee beans processed using this method to market. Based on information from these eight estates, we can roughly categorize red wine processing methods into three types: acetic acid fermentation (Aerobic fermentation), lactic acid fermentation (Anaerobic fermentation), and mixed fermentation (Mix Fermentation = Aerobic + Anaerobic).

Advantages of Red Wine Processing

Traditional processing methods struggle to control the varying degrees of coffee bean fermentation. However, the red wine processing method can ensure coffee bean quality by controlling pH values, and even temperature and humidity, while sealed fermentation prevents aromatic compounds from easily evaporating.

The Fermentation Process

Next, let's discuss the specific fermentation process. First, Colombian farmers carefully harvest coffee cherries and meticulously select red coffee fruits, ensuring that among the selected coffee cherries for processing, the ratio of unripe cherries is less than 2%, defective beans less than 3%, and floaters less than 5%.

The selected coffee cherries are then placed by farmers in specific containers (when Australian barista Sasa competed, the beans she used were processed in metal containers). Regardless of the container type, it should be equipped with something similar to a red wine fermentation lock or a one-way exhaust valve. This setup allows carbon dioxide to escape through this device, controlling the air concentration inside the container. At this point, the coffee cherries in the container undergo acetic acid fermentation, resulting in beans with relatively bright, clean flavors and lemony acidity.

According to Sasa's description during the competition, processors inject carbon dioxide into the container to prevent oxidation from forming volatile acids. This process is lactic acid fermentation, which produces malic acid and tartaric acid. Since tartaric acid is relatively stable, beans produced through lactic acid fermentation have a mellower acidity, with cheese-like, nutty, and creamy flavors.

Characteristics of Different Fermentation Methods

Aerobic Fermentation = Acetic Acid Fermentation (AEROBIC)

Flavor characteristics: Cleaner, bright and lively acidity, citric and citrus acids.

Anaerobic Fermentation = Lactic Acid Fermentation (ANAEROBIC)

Flavor characteristics: Round, high body, relatively lower cleanliness, malic and tartaric acids.

Mixed Fermentation = (MIX FERMENTATION = AEROBIC + ANAEROBIC)

Flavor characteristics: Full, medium body, smooth, fruit acids, amino acids, nuts, cream.

Summary of Green Coffee Processing Methods

All green coffee processing methods are designed to provide consumers with richer and more diverse coffee flavors.

They can be categorized into three main types:

1. Different substances involved in fermentation (skin, pulp, pectin, microorganisms)

2. Different fermentation environments (pH values, with or without water, with or without oxygen)

3. Different drying processes (natural sun drying, drying equipment, turning frequency, container materials)

By utilizing natural elements like sunlight, water, and wind in combination with the green coffee beans themselves, more aromatic compounds are preserved in the coffee.

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