what?

Fermentation is a biological process that transforms food, particularly sugar, into various end products through the enzymes produced by microorganisms such as yeast, bacteria and molds.

the basic principles of fermentation.

Bacteria and yeast serve as the primary generators for the fascinating process of fermentation. These microorganisms metabolize starches and various organic compounds present in food, resulting in the creation of diverse compounds, including alcohol, acids, and gases. The intricate dance of biological processes during fermentation involves a myriad of activities, with a particular focus on the breakdown of complex starches and proteins into their simpler counterparts. The conversion of starches into simple sugars and the transformation of proteins into amino acids, processes that highlight the essence of fermentation.

This process allows the development of unique and complex flavors that we perceive when consuming fermented foods. The individual molecules of starch and protein are literally too large for our taste receptors to directly recognize. Yet, through the process of fermentation, specific attributes of food become more discernible to our palate.

Fermentation in food covers a wide array of biological processes driven by microorganisms. These single-celled organisms are alive and found everywhere, on/inside our bodies, on the food we eat and the surfaces which we eat them on.

Lactic acid fermentation, primarily lead by various strains of lactic acid bacteria (LAB) and a few others, namely, streptococcus and pediococcus species. These bacteria thrive in anaerobic, low-pH environments. They work to covert sugars, such as lactose or glucose into lactic acid which not only imparts unique flavors but works to preserve the final products. They are responsible for products such as yogurt, kimchi, sauerkraut and sourdough bread. Moreover, the production of lactic acid bacteria brings forth different complexities of flavor and aromas. Namely, sourness, creaminess, tanginess, umami and tart vinegar-like smells.

Alcoholic fermentation, more specifically the process of sugars being converted to ethanol. Saccharomyces cerevisiae is the most widely used species of yeast for brewing alcohol, although there are other species of yeast and bacteria that are also capable of producing ethanol. Alcoholic fermentation contributes to a vast variety of flavor compounds, contributing to the depth of taste and aroma of fermented products such as wine, beer and bread. In the world of brewing, the choice of yeast plays a major role in creating these compounds, with different strains of yeast contributing different flavors. Aroma and flavor compounds such as esters, aldehydes, higher alcohols (isoamyl & propanol), organic acids, phenols, diacetyl all play a role in the complexity found in alcoholic beverages.

Acetic acid fermentation involves the conversion of alcohol into acetic acid by acetic acid bacteria (AAB). Unlike lactic acid fermentation, which occurs anaerobically, this process requires the presence of oxygen. When a liquid containing ethanol is exposed to AAB, the alcohol undergoes oxidation in the presence of oxygen. This oxidative transformation takes place through a series of enzymatic reactions facilitated by the presence of AAB, ultimately resulting in the production of acetic acid. Picture the distinctive sharp and sour flavor of vinegar; this is the characteristic taste produced by this fermentation. However, acetic acid fermentation plays a crucial role in various other food items, including pickles, kombucha, fermented vegetables, fish sauce, and cured meats. In environments lacking ethanol, AAB exhibit a unique capability to break down and oxidize various organic compounds, contributing to flavor development as well.

why?

survival & evolution.

Fermentation stands as one of the oldest food processing methods, initially developed to preserve food for survival. Similar to curing, drying, smoking, pickling, etc. However, "developed" may not be the most apt word choice; "discovered" or "harnessed" would be more fitting. It is believed that early humans, driven by observation and experimentation, found that certain perishable foods could still be consumed under specific conditions, even after prolonged periods, without causing harm or illness. Fermentation, an age-old practice, has played a vital role in food production for thousands of years. This unique attribute has been leveraged by diverse cultures and communities throughout history as a means to extend the shelf life of food items without modern day refrigeration. The ability of fermented foods to resist spoilage has been a key factor in sustaining humans during periods of scarcity and preserving seasonal harvests.

As discussed earlier, during fermentation, microorganisms produce organic acids and alcohols as byproducts which in turn lower the pH of food, creating acidic environments. This inhibits the growth of harmful and spoilage-causing bacteria and pathogens. During alcoholic fermentation, preservation is further enhanced by additional compounds like bacteriocins, which are antibiotics that inhibit the growth of similar harmful bacterial strains. Although it is important to note that proper hygiene and environmental conditions such as temperature and salt concentration are crucial for successful and safe fermentation. This probably means many, many people have died or gotten sick in the sake of learning while trying to make various ferments.

flavor.

Flavor in food is a multifaceted sensory experience resulting from a combination of factors. Such as taste, aroma, texture, temperature, sound, touch, visual stimuli and environment.

Fermentation over time has become responsible for some of human kind’s most unique, complex and delicious creations. Many of the foods we consume whether we know it or not have been transformed or somehow changed effectively through the addition of one or more elements of fermentation. Take for example, bread which is consumed by probably the whole world, or wine, cheese, beer, soy sauce, yogurt and vinegar.

Most food we eat would taste better with a touch of acid, in the case of fermentation where acid is made naturally, it only makes sense to include fermented ingredients/foods into our recipes. A lot of fermented foods tend to provide a combination of enhanced tastes and aromas.

further learning:

• The Noma guide to fermentation, by: Rene Redzepi & David Zilber.

• Food Fermentation - an overview | ScienceDirect Topics

• An overview of fermentation in the food industry - looking back from a new perspective | Bioresources and Bioprocessing | Full Text (springeropen.com)