Difference between revisions of "Solid state fermentation"

Solid state fermentation (SSF) is a type of [[fermentation]] with a low water content in the [[substrate]]. The solid substrate is inoculated with the culture and the cultivation is mostly performed under controlled conditions, such as controlled temperature, light and humidity. Nutrient levels, C/N ratio, feedstock-to-inoculum ratio, pH and mixing can also be controlled.<ref name=":0" /> SSF is "a traditional cultivation technique of food technology and involves all cultivations of microorganisms on a solid substrate without free liquid phase."<ref name=":0">{{Cite book|author=Dr. Susanne Steudler, Dr. Anett Werner, Dr. Jay J. Cheng|year=2019|book_title=Solid state fermentation : research and industrial applications|publisher=Springer International Publishing|place=Cham|ISBN=978-3-030-23675-5}}</ref> Besides traditional food processing methods, solid state fermentation is also used for the industrial production of a diverse range of other products, such as enzymes, biogas, pigments, antibiotics. SSF can be applied in many different fields, such as food and aroma production, production of medicines, waste treatment or environmental technology.

One example for a traditional solid state fermentation is the production of Sake (a Japanese alcoholic beverage from rice). The polished and cooked rice serves as the solid substrate of the first fermentation step in the Sake production process. It is inoculated with Kōji-kin (''Aspergillus oryzae'') spores.<ref>{{Cite journal|title=Genomics of Aspergillus oryzae: Learning from the History of Koji Mold and Exploration of Its Future|year=2008-8|author=Masayuki Machida, Osamu Yamada, Katsuya Gomi|journal=DNA Research: An International Journal for Rapid Publication of Reports on Genes and Genomes|volume=15|issue=4|page=173–183|doi=10.1093/dnares/dsn020}}</ref> ''A. orizae'' is a fungus which converts the starch from the rice to sugar. After this solid state fermentation, a liquid state fermentation step follows during which yeast converts the sugar to ethanol.