Fermentation is a biological processes that occurs when the lactic acid bacteria consume the sugars that is present in the food. Lactic acid fermentation is a process that transform the simple sugars into lactic acid, which acts as a natural preservative for the food. When the lactic acid bacteria consume the sugars in the food, the bacteria produce lactic acid as a byproduct of there consumption of those sugars.
The production of lactic acid decrease the pH level of the food, and a lower pH level mean that the food is acidic. Most harmful pathogen cannot survive in acidic environments, so the lactic acid fermentation process preserves the food. Depending on the type of lactic acid bacteria that is present in the food, the bacteria can vary the chemical paths that are taken.
How Lactic Acid Fermentation Works
For example, some types of lactic acid bacteria will convert the sugar into almost entirely lactic acid, but other types will produce a combination of lactic acid, ethanol, and carbon dioxide. Foods like sauerkraut, for instance, is produced by bacteria that produce almost entirely lactic acid, giving the sauerkraut its characteristic sharp and clean taste. Foods like kefir and sourdough bread, however, contain bacteria that produces carbon dioxide, which creates the bubbles that are characteristic of those foods.
You need to manage the amount of salt and the temperature of the environment in which the lactic acid fermentation process occurs. Salt is required for the process; it inhibits the growth of spoilage organisms in the food yet allows the lactic acid bacteria to grow. If the amount of salt is too low, the food may develop a mushy texture and may contain unwanted mold in the food.
Too much salt, however, may stall the fermentation process altogether. In addition to salt, the process also requires that you control the temperature of the environment in which the food ferments. Fermentation is a process that rely on the lactic acid bacteria to perform its tasks, and the temperature of the environment determines how quickly the bacteria perform their tasks.
Another factor to consider in the lactic acid fermentation process is the passage of time. The pH level of the food change over time. As the lactic acid bacteria perform their tasks of consuming the sugars in the food and producing lactic acid as a byproduct, the pH level of the food steadily decline.
As the pH level declines, the acidity of the food increases. At the beginning of the food fermentation process, the pH level of the food is neutral. The various strains of bacteria that live in the food compete for dominance throughout the beginning of the food fermentation process.
As the food becomes increasingly acidic, the strains of bacteria that can tolerate acids begin to take over the food, continuing the production of lactic acid until the food reaches a pH level that indicates that the food is shelf stable. As the pH level of the food changes gradualy over time, the flavor of the food becomes more complex. You also need to ensure that the food ferments in an environment that is away from the presence of oxygen.
Oxygen is problematic during the fermentation process because it can promote the growth of molds and yeasts that are not beneficial to the lactic acid fermentation of the food. To prevent the presence of oxygen in the food, it is possible to use weights to keep the vegetable submerged in the brine, or use airlocks to allow the gases to escape from the food yet still prevent the entrance of air into the food. If the food begins to show the presence of a white, flat film on the surface of the food, the food may contain Kahm yeast.
You can remove Kahm yeast from the surface of the food. However, if the food contains fuzzy or colorful mold on the surface of the food, oxygen has likely reached the food, and the food should not being consumed. Lactic acid fermentation transforms raw ingredient into food that contains probiotic benefits.
You begin with a raw ingredient, such as a vegetable, and the lactic acid fermentation process transforms that ingredient into a food that is often more digestible than the raw ingredient that you started with. Through the control of the amount of salt, oxygen, and the temperature of the environment in which the food ferments, you are able effectively manage the environment in which the lactic acid bacteria live and perform the lactic acid fermentation process.