What are the fundamentals of fermentation?

In general, fermentation is the process of leveraging a specific bacteria or yeast to change the flavor, texture, or nutritional usefulness of an ingredient. Fermentation encompasses many specific and complicated processes: alcohol, bread, cheeses, soy & miso products, and vinegar are all produced with unique bacterial strains and processes.

• Fermenting typically involves placing an ingredient into a closed environment with a bacteria or yeast culture and letting it sit at a controlled temperature.
• Fermentation can happen without added yeast and instead depends on naturally present bacteria on the exterior of ingredients, however, as in the case of lacto-fermented vegetables.

During fermentation, the bacteria or yeast consume the natural sugars in an ingredient, producing byproducts like lactic or acetic acid, alcohol, and CO2 that can give the food or drink a tangy or sour taste, an astringent or dry mouthfeel, or an airy, bubbly, or effervescent texture.

Is fermenting similar to pickling? Pickling uses already acidic ingredients (like vinegar, which has already been fermented) to preserve an ingredient, while fermentation creates its own acidic environment.

➡️ Catalyst: Specific bacteria or yeast strains in a controlled environment

🛠️ Relevant techniques: N/A

🔬 Relevant molecules: Carbohydrate alcohol

Example foods

• Sourdough and yeast donuts
• Kimchi and lacto-fermented pickles
• Yogurt and cheese
• Wine & beer
• Tepache and kombucha
• Vinegar
• Soy sauce & miso paste

How does fermentation affect the elements of flavor?

In order of importance:

Taste — Because yeast consumes sugars and produces lactic acid, fermented foods are often sour and less sweet than what they started as. In the case of alcohol production, ethanol molecules can be slightly sweet or bitter.

Aroma — Fermentation produces dozens of new aroma molecules. Fermented foods are often much more complex in flavor than their raw counterpart. In general, fermented products might smell pleasantly funky or strong.

Texture — Fermentation changes texture in a few ways. In bread, it creates air pockets that make for a lighter dough. Fermented vegetables, like kimchi, become softer and more watery. In the case of fermented drinks, they can become bubbly and effervescent.

Physical — Fermented foods are often easier to digest than their raw counterparts. If fermented products contain alcohol, they have a psychological effect on our brains, which changes our perceptions of food and our surroundings. Fermented foods, like wine or chocolate, are often astringent, which causes our mouths to contract with a drying sensation.

Human — Fermentation has been an important part of human survival and cuisine history. Fermented food and drinks can be found in every culture. Depending on your lived experience, different fermented products may be associated with certain traditions or emotions, like kimchi or labneh.

Sight — Fermentation can change the shape and crumb of baked goods, or the color of a vegetable or drink. In the case of beer or tepache, we’ll often look for bubbles or foam as a sign of a healthy fermentation. A saggy loaf of bread or a flat beer are less appetizing just by sight.