Oriental Fermented Foods

Soy Sauce

Soy sauce, a dark, salty, tangy sauce used on foods such as chop suey or as a component of other sauces, is the principal fermented Oriental cuisine imported into the United States and also produced here. Numerous variants exist in the creation of the starter and the production of soy sauce, which may result in distinct product varieties.

The Starter

The starters (koji or chou) may be pure cultures cultivated independently or mixed cultures carried over from earlier batches.
The substrate on which the starter is grown varies, but is typically an autoclaved mixture of soybeans, cracked wheat, and wheat bran; a combination of wheat bran and soybean flour; or rice.
This substance is injected with Aspergillus oryzae (A. soyae) spores, dispersed in small boxes or trays, and maintained at 25 to 30 degrees Celsius until the mould growth on the surfaces of the mash has reached its maximum enzyme concentration (usually after about 3 days).
A flora of lactic acid bacteria, streptococci and lactobacilli, as well as lactose-producing lactobacilli and Bacillus spp., develops in the koji and creates lactic acid.
The starter may be used immediately as is, dried and used later, or dried, extracted, and the extract utilised.

Manufacture of soy sauce

The mash may consist of autoclaved or chemically hydrolyzed, defatted soybeans, roasted and pulverised wheat, and steamed wheat bran.
The mash is inoculated with koji and incubated in trays at 30 degrees Celsius for three days. Then it is steeped in a sterile brine containing 24 percent sodium chloride (sometimes the koji is mixed directly with an equal amount of saline water).
Depending on the temperature, the brined mash is stored for a minimum of 2.5 months and up to a year.

Fermentation

Throughout the holding time, the proteinases, amylases, and other enzymes of the koji continue to function.
There are three stages in the curing process: (1) lactic acid fermentation by lactic acid bacteria from the koji, followed by more acid production by Pediococcus halophilus, (2) alcoholic fermentation by yeasts such as Saccharomyces rouxii and Zygosaccharomyces saccharomycessoyae, and (3) completion of fermentation and ageing.
The essential microorganisms for the production of soy sauce may be added in pure culture or obtained from previous koji batches and the ingredients.
The most important organism is Aspergillus soyae (oryzae), which grows in the koji to produce proteinases, amylases, and other enzymes for soy-sauce brewing and contributes aromas and flavours; lactic acid bacteria, e.g. Lactobacillus delbrueckii, which makes the koji acidic enough to prevent spoilage and acidifies the mash; Bacillus subtilis and other bacilli,

Tamari Sauce

This is a Japanese sauce similar to soy sauce that is produced by a brief fermentation process from a soybean mash to which rice may be added.
Aspergillus tamarii, a separate fungus, is the primary fungus involved in the production of tamari sauce.

Miso

Miso koji is a culture of Aspergillus oryzae cultured at around 35 degrees Celsius on steamed polishedrice mash in shallow trays until the grains are thoroughly covered but the mould does not sporulate.
The koji is combined with a mash of crushed, steamed soybeans, salt is added, and the mixture is fermented for a week at 28 C and then for two months at 35 C, following which it is aged for several weeks at room temperature.
Enzymes of the koji, yeasts (saccharomyces rouxii and Zygosaccharomyces spp.), lactic acid bacteria, and bacilli are involved in the primary fermentation. The finished product is ground into a paste for usage with other foods.

Tempeh

In the production of tempeh, an Indonesian food, soybeans are soaked overnight at 25 degrees Celsius, the seed coats are removed, and the beans are boiled in water for 20 minutes before being dried on mats, cooled, and inoculated with mould spores of species of Rhizopus.
The mush is placed into a plastic container, hollow tube, or banana leaf roll.
It is then incubated at around 32 degrees Celsius for 20 hours, when there is good mycelium development but little sporulation.
The product is thinly sliced, dipped in salt water, and golden-fried in vegetable grease.

Ang-khak

Ang-khak, or Chinese red rice, is created by the growth of Monascus purpureus on rice that has been autoclaved and is used to colour and flavour fish and other foods.

Natto

When making natto, cooked soybeans are wrapped in rice straw and fermented for one to two days.
The package’s outside gets slimy. Bacillus natto*, which is likely identical to Bacillus subtilis, thrives in natto and secretes trypsin-like enzymes believed to be essential to the ripening process.

Soybean Cheese

Tofu is a Chinese fermented meal created by soaking soybeans, pounding them into a paste, and then straining them through linen.
A magnesium or calcium salt is used to curdle the filtrate’s protein, following which the curd is compressed into blocks.
The blocks, stacked on trays, are kept in a fermentation room at around 14 degrees Celsius for one month, during which time white moulds, likely Mucor spp., form. Final maturation occurs in brine or a particular wine.

Minchin

Wheat gluten from which the starch has been extracted is used to make fermented minchin.
The raw, moist gluten is sealed in a jar and allowed to ferment for two to three weeks before being salted.
A typical sample was found to contain seven mould species, nine bacterial species, and three yeast species.
The finished product is sliced into strips for boiling, baking, or frying.

Idli

Idli, an Indian fermented meal, is composed of equal parts rice and black gramme mungo. The components are separately rinsed and soaked, then crushed and let to ferment overnight.
When the batter has sufficiently risen, it is steamed and served hot. Leuconostoc mesenteroides, which leavesns the batter, grows first, followed by Streptococcus faecalis and Pediococcus cerevisiae*, which all contribute to the acidity.

Fermented Fish

The Japanese prepare fermented fish by slicing it into strips, frying it, and then allowing fungi, primarily Aspergillus species, to promote fermentation.
Next, the strips are dried. The Chinese preserve fermented fish in lao-chao, which is a fermented rice product.
Molds and yeasts are involved in the fermentation of steamed rice, which results in the production of alcohol.

Preserved Eggs

Pidan, also known as the Chinese preserved egg, is composed of duck eggs coated with a slurry of soda, burned straw, salt, and slaked lime and covered with rice husks.
The eggs are then stored in sealed clay jars for at least one month.
A variety of bacteria thrive in the egg, but coliform bacteria and Bacillus species appear to predominate.

Poi

Although Poi is Hawaiian and not Asian, it will be addressed here. The corms (bulbous, fleshy stems) of the taro plant are cooked at 70 to 100 degrees Celsius for two to three hours, cooled, rinsed, peeled, trimmed, and scraped before being finely pulverised.
This pulverised substance, after being combined with water to achieve the desired consistency, is fresh, consumable poi.
The sour or fermented poi is made by incubating fresh poi in barrels or other containers at room temperature for at least one day and no more than six days.
During the first six hours of fermentation, the poi swells and changes colour somewhat.
During this time, a variety of soil and water microorganisms, such as coliforms, Pseudomonas spp., chromogenic bacteria, and yeasts, are prevalent.
Between 6 hours and 4 days, acid-forming bacteria dominate the flora, including Lactobacillus pastorianus*, L. delbrueckii, L. brevis, Streptococcus lactis subsp. lactis, and S. kefir (Leuconostoc).
These lactic acid bacteria are responsible for the majority of the fermentation in poi, while yeasts, film yeasts, and the mould Geotrichum candidum likely contribute fruity aromas and flavours at the end of the process (bouquet).
The primary products of fermentation are lactic, acetic, and formic acids, alcohol, and carbon dioxide.
Typically, aberrant fermentations are of the butyric acid variety.