Kombucha is a fermented, lightly effervescent beverage with a distinctively tangy and slightly sweet flavor profile. This drink has ancient origins, with consumption reported as early as 220 B.C. in China, and has a long history of use in various cultures around the world. The resulting beverage contains a variety of compounds, including organic acids, B vitamins, and amino acids.
The Essential Trio: Tea, Sugar, and Water
Kombucha production begins with three ingredients: tea, sugar, and water. True kombucha relies on tea derived from the Camellia sinensis plant, which includes black, green, and oolong teas. These teas provide necessary nutrients, such as nitrogen, that nourish the live cultures responsible for fermentation. Most herbal teas are not suitable for the primary brewing process, as they lack these specific compounds.
Sugar is another primary component, but its main purpose is to act as food for the culture, not to sweeten the final drink. Plain white cane sugar, or sucrose, is the most common and effective type used because it is easily metabolized by the microorganisms.
The quality of the water used is also a factor in successful kombucha brewing. It is recommended to use filtered water that is free of chlorine, as chemicals in tap water can be harmful to the microorganisms and hinder fermentation.
The SCOBY: A Symbiotic Culture
The living culture that drives kombucha’s transformation is known as a SCOBY. The term SCOBY is an acronym that stands for Symbiotic Culture Of Bacteria and Yeast. Visually, it appears as a gelatinous, rubbery, pancake-like disc that floats at the surface of the brewing liquid. This structure is primarily composed of a type of insoluble fiber called cellulose, which is created by the bacteria.
The SCOBY is a complex, living ecosystem where multiple species of bacteria and yeast coexist. The yeast component includes various species, while the bacterial side contains acetic acid bacteria. Often called a “mother,” a SCOBY can be reused to start subsequent batches.
The Fermentation Transformation
Once the sweetened tea has cooled to room temperature, the SCOBY and a small amount of previously fermented kombucha, known as starter tea, are added. The mixture is then left to ferment in a covered container for a period that typically lasts from one to three weeks. The temperature of the brewing environment is important; if it’s too cool, the culture may become dormant, and if it’s too hot, the culture could be damaged.
During this time, a two-stage metabolic process unfolds. First, the yeast in the SCOBY consumes the sucrose and converts it into ethanol (alcohol) and carbon dioxide. Following this, the bacteria get to work, metabolizing most of the ethanol and converting it into various organic acids, primarily acetic acid. It is these acids that give kombucha its characteristic tangy flavor, while the trapped carbon dioxide provides its natural fizziness.
Flavoring with Fruits and Spices
While the initial brew creates the foundational kombucha, the wide array of flavors available on the market is achieved through a subsequent step. This process is often called secondary fermentation, and it occurs after the SCOBY has been removed from the liquid. During this stage, brewers add various ingredients to the unflavored kombucha to infuse it with new tastes and aromas.
Common flavoring agents include fruit purees and juices, such as mango, raspberry, or ginger. Whole herbs and spices like lavender, mint, or cloves are also popular additions. This secondary fermentation is typically done in sealed, airtight bottles, which allows the carbon dioxide produced by the remaining yeast consuming the new sugars to be trapped, enhancing the drink’s carbonation. The length of this stage can range from a few days to a week, depending on the ingredients used and the desired level of fizziness.