Editing Miso (section)

== Fermentation ==
[[File:Miso packs Apr 30 2019 04-28PM.jpeg|thumb|Fresh ''miso'' sold in [[Mito, Ibaraki|Mito City]], Japan]]
Miso's unique properties and flavor profile can be attributed to the compounds produced through the fermentation process. Miso, depending on the variety, consists of a starter culture called {{lang|ja-Latn|[[Aspergillus oryzae|kōji]]}} ({{lang|ja|麹}}), soybeans, and usually a grain (either rice, barley, or rye).<ref name="Oxford Companion 3 ed">{{Cite book |title="miso" The Oxford Companion to Food (3 ed.) |last1=Davidson |first1=Jaine |last2=Alan |first2=Tom |publisher=Oxford University Press |year=2014 |isbn=9780199677337 }}</ref> The miso goes through a two-step process; first creating the {{lang|ja-Latn|kōji}}, and second the {{lang|ja-Latn|kōji}} is combined with the other components, and the mixture is left to be enzymatically digested, fermented and aged.

=== Creating koji ===
[[File:CodazziMisoKioke1.jpg|thumb|250px|[[Hatchō Miso|''Hatchō miso'']] fermenting in barrels]]
Koji is produced by introducing the [[mold]] ''[[Aspergillus oryzae]]'' onto steamed white rice. This mold culture comes from dried ''A. oryzae'' spores called {{lang|ja-Latn|tane-kōji}} ({{lang|ja-Hani|種麹}}, {{lang|ja-Hira|たねこうじ}}) or "starter koji" and is isolated from plant matter (usually rice) and cultivated.<ref name=":1">{{cite book |title=Industrialization of indigenous fermented foods |date=1989 |publisher=M. Dekker |isbn=978-0824780746 |location=New York |pages=99–112 |editor-last=Steinkraus |editor-first=Keith H. }}</ref> In the past, the natural presence of ''A. oryzae'' spores was relied upon to create koji, but because of the difficulty of producing the culture, {{lang|ja-Latn|tane-kōji}} is added almost exclusively in both industrial and traditional production of miso. {{lang|ja-Latn|Tane-kōji}} is produced much in the same way as koji, but also has a small portion of wood ash added to the mixture<ref name=":0">{{Cite book |title=Encyclopedia of Food Microbiology, Volumes 1–3 |last=Robinson |first=Richard K. |publisher=Elsevier |year=2000 |pages=66, 67 }}</ref> which gives important nutrients to the fungus as well as promoting [[sporulation]].

''A. oryzae'' is an aerobic fungus and is the most active fermenting agent in koji<ref name="Oxford Companion 3 ed"/> as it produces [[amylolytic]], and proteolytic enzymes which are essential to creating the final miso product. Amylolytic enzymes such as amylase aid in the breakdown of starch in the grains to sugar and dextrin,<ref>{{cite web |url=http://www.oed.com/view/Entry/6837?redirectedFrom=amylolytic#eid |title=amylolytic, adj |website=OED Online |publisher=Oxford University Press |access-date=12 March 2016 }}</ref> while proteolytic enzymes such as protease catalyze the breakdown of proteins into smaller peptides or amino acids. These both aid in the enzymatic digestion of rice and soybeans. Depending on the strain of ''A. oryzae'', the enzymatic composition varies, thereby changing the characteristics of the final miso product. For example, the strain used to create the sweeter white miso would likely produce a higher content of amylolytic enzymes, while comparatively, soybean miso might have a higher content of proteolytic enzymes.

To create optimal conditions for enzymatic production and the growth of ''A.&nbsp;oryzae'', the koji's environment must be carefully regulated. Temperature, humidity, and oxygen content are all important factors in maximizing mold growth and enzyme production and preventing other harmful bacteria from producing. Once the koji has reached a desirable flavor profile, it is usually mixed with salt to prevent further fermentation.<ref name=":2">{{cite book |title=The book of miso. savory, high-protein seasoning |url=https://archive.org/details/bookmisosavoryhi00shur/page/n235 |url-access=limited |last2=Aoyagi |first2=Akiko |date=2001 |publisher=Ten Speed Press |isbn=978-1580083362 |edition=2nd |location=Berkeley |pages=232–237 |last1=Shurtleff |first1=William}}</ref>

Although other strains of fungi have been used to produce koji, ''A.&nbsp;oryzae'' is the most desirable because of several properties, including the fact that it does not produce [[aflatoxin]].<ref name=":0" />