You know that tempeh is a fermented food, but what is fermentation exactly? The scientific meaning of fermentation is the energy-yielding anaerobic metabolism of a nutrients, such as sugars, without oxidation. Fermentation converts these nutrients mainly into lactic acid, acetic acid, and ethanol.

These are fermentation end product of some microorganisms: In a broader meaning, fermentation refers to the growth of microorganisms on food. Here no distinction is made between aerobic (oxygen is used) and anaerobic (no oxygen is used) metabolism. We will here use this broader meaning of fermentation. Fermentation will gradually change the characteristics of the food by the action of enzymes, produced by some bacteria, molds and yeasts.

Fermented soy products are very health and are available in different forms: miso, tempeh and natto. Other types of fermentation are lactic acid fermentation, alcohol fermentation and acetic acid fermentation.

Safety of fermented food

Fermented foods have a very good safety record, even in developing countries where food is produced under poor hygienic conditions. Fermented foods are overgrown by desirable and edible microorganisms, thereby reducing the risk of contamination with pathogens such as salmonella and Clostridium. During the tempeh fermentation ideal conditions are created for the Rhizopus mold: rather dry substrate, low pH and high amounts of Rhizopus spores. The low pH of the soybeans is obtained by a natural lactic acid fermentation in the soaking water or by an artificial addition of acids (lactic or acetic acid) after the soaking process.