Traditional Fungal Food -Shoyu for PG students in Mycology

1. TRADITIONAL FUNGAL FOOD:
SHOYU
M.Sc. Part II SEM IV
Paper IV UNIT IV
Sanjay M. Desai

3. Outline of koikuchi fermentation
(after Yokotsuka, 1981)

5. Introduction
• Soy sauce , also spelled as soya sauce is a
liquid condiment of Chinese origin, traditionally
made from a fermented paste of
soybeans, roasted grain, brine, and
Aspergillus oryzae or Aspergillus sojae molds.
• Soy sauce in its current form was created about
2,200 years ago in ancient China,
• Spread throughout East and Southeast Asia
where it is used in cooking and as a condiment.

6. Introduction
Historical Aspect: Originally, a common Japanese
condiment was uoshōyu, which was fish
based.[15]
When Buddhism came to Japan from China in the
7th century,[16] they introduced vegetarianism
and brought many soy based products with them,
such as soya sauce,[15] which is known
as shōyu[17][9] in Japan.
Shoyu exportation began in 1647 by the Dutch
East India Company.[9]

7. PRODUCTION
• Soy sauce is made either by fermentation or
by hydrolysis. Some commercial sauces have both
fermented and chemical sauces.
• Flavor, color, and aroma developments during
production are attributed to non-
enzymatic Maillard browning.
• Variation is usually achieved as the result of
different methods and durations of fermentation,
different ratios of water, salt, and fermented soy,
or through the addition of other ingredients.

8. PRODUCTION
Traditional
• Traditional soy sauces are made by mixing soybeans
and grain with mold cultures such as Aspergillus
oryzae and other related microorganisms and yeasts
(the resulting mixture is called "koji" in Japan; the term
"koji" is used both for the mixture of soybeans, wheat,
and mold as well as for the mold itself). Historically, the
mixture was fermented naturally in large urns and
under the sun, which was believed to contribute extra
flavors. Today, the mixture is placed in a temperature
and humidity controlled incubation chamber.

9. PRODUCTION
Traditional soy sauces take months to make:
1. Soaking and cooking: The soybeans are soaked in
water and boiled until cooked. Wheat is roasted,
crushed.
2. Koji culturing: An equal amount of boiled
soybeans and roasted wheat are mixed to form a
grain mixture. A culture of Aspergillus spore is
added to the grain mixture and mixed or the
mixture is allowed to gather spores from the
environment itself.

10. PRODUCTION
The cultures include:
– Aspergillus: a genus of fungus that is used for
fermenting various ingredients (the cultures are
called koji in Japanese). Three species are used for
brewing soy sauce:
• A. oryzae: Strains with high proteolytic capacity are
used for brewing soy sauce.
• A. sojae: This fungus also has a high proteolytic
capacity.
• A. tamarii:This fungus is used for brewing tamari, a
variety of soy sauce.

11. PRODUCTION
– Saccharomyces cerevisiae: the yeasts in the
culture convert some of the sugars to ethanol
which can undergo secondary reactions to make
other flavor compounds
– Other microbes contained in the culture:
• Bacillus spp. (genus): This organism is likely to grow soy
sauce ingredients, and to generate odors and ammonia.
• Lactobacillus species: This organism makes a lactic acid
that increases the acidity in the feed.

12. PRODUCTION
3. Brewing: The cultured grain mixture is mixed into a
specific amount of salt brine for wet fermentation or
with coarse salt for dry fermentation and left to brew.
Over time, the Aspergillus mold on the soy and wheat
break down the grain proteins into free amino acid and
protein fragments and starches into simple sugars. This
amino-glycosidic reaction gives soy sauce its dark
brown color. Lactic acid bacteria ferments the sugars
into lactic acid and yeast makes ethanol, which through
aging and secondary fermentation makes numerous
flavor compounds typical of soy sauce.

13. PRODUCTION
4. Pressing: The fully fermented grain slurry is placed into
cloth-lined containers and pressed to separate the
solids from the liquid soy sauce. The isolated solids are
used as fertilizer or fed to animals while the liquid soy
sauce is processed further.
5. Pasteurization: The raw soy sauce is heated to
eliminate any active yeasts and molds remaining in the
soy sauce and can be filtered to remove any fine
particulates
6. Storage: The soy sauce can be aged or directly bottled
and sold.

14. References
• Wikipedia
• Biotechnology by R.C. Dubey
• https://www.miyajima-soy.co.jp/english-
site/en-fermented-foods/about-shoyu