Production
Tempeh begins with whole soybeans, which are softened by soaking and dehulled, then partly cooked. Specialty tempehs may be made from other types of beans, wheat, or may include a mixture of beans and whole grains , instant credit score checks.
A mild acidulent, usually vinegar, may be added in order to lower the pH and create a selective environment that favors the growth of the tempeh mold over competitors. A fermentation starter containing the spores of fungus Rhizopus oligosporus is mixed in. The beans are spread into a thin layer and are allowed to ferment for 24 to 36 hours at a temperature around 30°C (86°F). In good tempeh, the beans are knit together by a mat of white mycelia.
Under conditions of lower temperature, or higher ventilation, gray or black patches of spores may form on the surface—this is not harmful, and should not affect the flavor or quality of the tempeh. This sporulation is normal on fully mature tempeh. A mild ammonia smell may accompany good tempeh as it ferments, but it should not be overpowering. In Indonesia, ripe tempeh (two or more days old) is considered a delicacy.
Nutrition
The soy protein in tempeh becomes more digestible as a result of the fermentation process. In particular, the oligosaccharides that are associated with gas and indigestion are greatly reduced by the Rhizopus culture. In traditional tempeh making shops, the starter culture often contains other beneficial bacteria that produce vitamins such as B12[1][2] (though it is disputed whether this B12 is "bioavailable"[citation needed]). In western countries, it is more common to use a pure culture containing only Rhizopus oligosporus.