Fermentation of Soy products

1. FERMENTED SOY PRODUCTS

2. Fermented Legumes
• Fermented food derived from legumes
are important part of the human diet in
South East Asia, Near East Asia, and
parts of Africa
• Represent about 20% of the protein
currently available to man in developing
countries

3. For more than 2,000 years, the modest little
soybean [Glycine max (L.) Merr., Leguminosae]
has provided us with nutrition and healing
power. New research shows that we derive the
greatest benefits from soybeans when they are
prepared in traditional ways, especially when
fermented.

4. Benefits of Soybean Fermentation
• Improved digestibility
• Enhanced nutrition
• Medicinal benefits
• Increased bioavailability
of isoflavones

5. Improved Digestibility
Unfermented soybeans are difficult to digest,
partly due to the high amount of protein
enzyme inhibitors and hard-to-digest sugar
structures. During fermentation, the enzymes
produced by beneficial microbes break down,
or predigest, specific complex carbohydrates
(sugars) found in soy. This process also renders
the proteins more digestible and easier to
assimilate than those in the whole soybean.

6. Enhanced Nutrition
Soy fermentation converts minerals such as
calcium, iron, magnesium, potassium,
selenium, copper, and zinc into more soluble
forms and can also increase vitamin levels in
the final product. Some beneficial yeasts,
such as Saccharomyces cerevisiae, are able to
concentrate large quantities of thiamin,
nicotinic acid, and biotin in soy, thus forming
an enriched product.

7. Medicinal Benefits
Substances in fermented soy foods have been
found to alleviate the severity of hot flushes,
to have a protective effect against cancer
development, to reduce cholesterol level, and
to inhibit the progression of atherosclerosis.
Probiotic bacteria produced during soy
fermentation are known to enhance healthy
intestinal flora and correct digestive tract
imbalance.

8. Increased bioavailability
of isoflavones
Isoflavones (phytoestrogens naturally
occurring in soy) are converted by the
bacteria into their “free” or aglycone
forms for improved absorption and more
effective usage within the body.

9. Popular Fermented
Whole Soy Foods
1. Soy sauce
2. Tempeh
3. Natto
4. Miso
5. Fermented tofu
6. Fermented soymilk or yogurt
7. Fermented soy powder

11. SOY SAUCE
A condiment produced from the fermented
paste of boiled soybeans, roasted grains, brine
and Aspergillus oryzae or Aspergillus sojae
• Originated from China in 200 BC, but
popularized worldwide by Japan (Kikkoman)
• Considered as the world’s oldest condiment
• A traditional ingredient in East and Southeast
Asian cuisines.

12. NATURAL BREWING OF SOY SAUCE
Accomplished in three distinct steps
1. Koji making
2. Brine Fermentation
3. Refining

13. Koji making
Carefully selected soybeans and wheat
are blended under precisely controlled
conditions. Next, a proprietary seed mold
(tane koji) is introduced, and the mixture
is allowed to mature for three days in
large air-circulated perforated vats.

14. Brine Fermentation
The resulting culture, or koji, is transferred to
fermentation tanks and mixed with soybeans,
wheat and saltwater, to produce moromi, which is
then allowed to ferment for several months using
osmophilic lactic acid bacteria and yeasts.
• During this time, the soybeans and wheat are
transformed into a semi-liquid, reddish-brown
"mature mash."
• This process creates the many distinct flavor and
fragrance compounds that build the soy sauce
flavor profile.

15. Refining
After months of moromi fermentation,
the raw soy sauce is separated from the
solids by pressing it through layers of
filtration cloth. The liquid that emerges is
then refined, pasteurized and packaged
as finished soy sauce.

16. DIAGRAM OF
SOY SAUCE
PRODUCTION

17. Method of Soy Sauce Production
Rice
Soak
Drain
Steam for 40 min
Inoculate with spores of A. oryzae
Incubate at 30°C for 3 – 4 days
Koji

18. Production of Soy Sauce
Soybean
(4 kg)
Wheat
(3.4 kg)
Koji
Soak in
water (15
h, ART
Roast and
crush
Autoclave
1 h, 10 psi Coat
soybean
with
powder
wheat
Cool
Mix

19. Mix
Ferment at 25 – 35 ° C for
50 – 72 h
Add brine solution (20 L) =
salt, 2.76 kg; water, 12 L
Agitate with compressed
air for 3 – 4 months
Add a culture of P. halophilus or L. delbrueckii
followed by a culture of S. rouxii after 1 month

20. Add a culture of P. halophilus or L. delbrueckii
followed by a culture of S. rouxii after 1 month
Age (1 year)
Press
Soy cake Raw shoyu

21. Biochemical Changes During
Soy Sauce Fermentation
1. The initial pH of moromi is around 6.5 – 7.0; it decreases to
4.8 – 5.0 through the combined action of A. oryzae and LAB
2. Hydrolytic enzymes, the Vitamin B group, sugars, peptides
and amino acids accumulates in the rice koji.
3. Carbohydrates are degraded to dextrin then to glucose.
4. Moisture is lost during koji preparation.
5. Proteins are decomposed by proteolytic enzymes.
6. The temperature of the fermenting beans increases.
7. Soluble solid increases (including sugar, alcohol, and other
compounds)
NOTE: Good soy sauce contains 1.5 – 1.8% total N, 2 – 5%
reducing sugars, 1 – 2% v/v alcohol, 1 – 2% organic acids and
18% salt and has a pH range of 4.6 -4.9.

22. Tempeh
• A fermented whole soybean product that
originated from Indonesia. It is made by natural
culturing and controlled fermentation that binds
soybeans into a cake form
• A white, mold-covered cake, produced by fungal
(R. oligosporus) fermentation of dehulled,
hydrated and partially cooked soybeans.
• Has clean, mushroom-like aroma; cooked by deep
frying
22

23. Etymology
• Suggested to have been derived from the old
Javanese term tumpi, a whitish food made
from sago
• However, the historian Denys Lombard
suggested that it is linked to the local term
tape or tapai, which means fermentation

24. Tempeh Production
Soybeans
Clean and wash
Soak overnight
Dehull
Boil for 30 min
Drain and Cool

25. Inoculate with spores of R.
oligosporus or old tempeh
Lightly pack in banana leaves or
perforated plastic bag
Incubate for 24 – 36 h at ca. 30 C
RAW TEMPEH

26. Starter Culture
• Previous batch of inoculated tempeh
• From previous leaf (hibiscus) wrappers or
bamboo trays
• “Ragi” or tempeh inoculum (cake form)
• Freeze-dried or sun dried sound tempeh
• Pure culture of R. oligosporus

27. Microbiology
• Mold - species belonging to the genus Rhizopus
The best strain is R. oligosporus, although R.
stolonifer, R. oryzae, and R. arrhizus may
also be used.
• Presence of bacteria for acid fermentation
during soaking

28. Control of Process
1. Hydration/Acid Fermentation
• Soaking of soybeans almost doubles its weight
• Involvement of acid producing bacteria – results in a
decrease in pH (4.5 – 5.3)
• The hydration time is usually 12 – 15 h
2. Partial Cooking
• Destroys contaminating bacteria
• Destroys trypsin inhibitor
• Releases some nutrients necessary for mold growth

29. Control of Process
3. Draining, cooling and surface drying
4. Inoculation
5. Fermentation container
• Banana leaves, wooden trays lined with
plastic, perforated plastic bags
• Container must permit access of O2, allow
temperature control, and enable moisture
retention by the beans during fermentation

30. Control of Process
6. Incubation temperature: 25 – 37 °C
• At 25 °C for 80 h; 28 °C for 26 h; 31 - 37 °C
for 22 – 24 h.
7. Harvesting and preservation
8. Preparation for consumption
• Deep-frying or boiling for 10 min

31. Biochemical Changes
1. The temperature of the fermenting bean mass
increases from 5 to 7 °C.
2. TSS increases from 13 to 28%.
3. Soluble N increases from 0.5 to 2.5%
4. pH increases from 5 to 7
5. Free ammonia increases at later stage of
fermentation
6. The concentrations of some vitamins (i.e.,
riboflavin, niacin, and Vitamin B12) increase

32. MISO
A salty, smooth to chunky paste made from
fermented soybean that has a meat-like flavor
and a high protein content.
A high-protein fermented food paste consisting
chiefly of soybeans, salt, and grains (such as
barley or rice) and ranging in taste from very
salty to very sweet
A fermented seasoning paste of soybeans, often
with rice or barley added, used to flavor soups
and sauces

33. Notes on Miso
• Can be produced with or without grain
addition of rice or barley, using A. oryzae, S.
rouxii, and P. halophilus
• Used for dips or dressing, pickling medium, as
seasoning, or dietary staple (in preparation of
miso soup)
• Color ranges from light yellow to dark brown
• Flavor varies from sweet to salty to meat-like

34. Types of Miso
1. White miso Has light color, sweet flavor, low
salt concentration, and short fermentation
time (~ 1 week at 23-33°C)
2. Edo miso Is light reddish-brown, has a
high salt concentration, and requires 2 weeks
of fermentation; popular around Tokyo,
Japan

35. Types of Miso
3. Sendai miso High salt concentration,
requires 1 year of fermentation; excellent
keeping quality
4. Shinshu miso Light yellowish-brown;
high salt concentration, requires >1 year
fermentation; popular in Tokyo and central
Japan

36. Types of Miso
5. Mame miso Made solely from soybeans;
deep reddish-brown; requires 2 years of
fermentation

37. Method of Miso Production
Rice
(600 kg)
A. oryzae
(600 g)
Polish
Soak in water
overnight
Cook in steam
Cool
Ferment
Koji
Inoculate

38. Method of Miso Production
Soybeans
(1000kg)
Salt
Clean and
wash
Soak
Cook under
pressure
Cool
Mix
Inoculate
with LAB
and yeast
Ferment MISO
KOJI

39. Major Steps in Miso Production
1. Soaking of Soybeans – 16 – 17 hours
• Doubles the original dry weight
• Softens the soybeans
• All beans should be hydrated uniformly
2. Cooking of soybeans
• Softens the beans and results in color change
in soybeans
• Shinshu miso – soybeans are cooked 1 hour at
7 psi, resulting in yellowish-brown in color
• Sendai miso – soybeans are cooked 2 hours,
10 psi and 30 mins at 5 psi, product has
reddish brown color

40. Major Steps in Miso Production
3. Preparation of koji
• Using either polished rice or barley
• Rice should be moist enough (38%) to permit
mold growth but not bacteria
• Temperature of rice should not exceed 43°C
during mold growth
4. Fermentation
• Use of wide-mouthed containers
• Maintenance of anaerobic condition
5. Storage at refrigerated temperature
6. Pasteurization
• Short-fermented miso is pasteurized to inactivate
enzymes

41. Control of Process
1. Koji preparation requires 40 h. The temperature of
fermenting rice should be held constant (opt. T° = 30°C)
2. RH is held at 95% for the first 24 h, but is reduced later to
decrease the possibility of bacterial growth.
3. The moisture content of rice should be about 38%.
4. A temperature of 30°C is optimum for the growth of LAB
and yeast.
5. During fermentation, the miso is turned once or twice to
cool.
6. A high proportion of koji speeds up fermentation.
7. To vary color, sweetness, salinity, and amounts of
carbohydrates, amino acids and peptones, proper control
of the cereal/soybean ratio, salt content, and the
temperature and length of fermentation is necessary.

42. Biochemical Changes
1. Production of enzymes by molds
• For example, amylases, proteases, and
lipases by A. oryzae
2. Production of Vitamin B2 (riboflavin) and
Vitamin B12 (cyanocobalamine) during
fermentation
3. Production of lactic acid and acetic acid,
which contributes to flavor development

43. Typical Miso Composition
Salt 5.5 – 13%
MC 42 – 47%
Protein 11.0 – 19.4%
Fat 4.0 – 9.9%
Ash 7.0 – 14.5%
CHO 13.2 – 34.9%

44. Fermented Whole Soybeans
and Paste
44

45. Fermented Whole Soybeans

46. Shoyu (soy sauce): Originally a by-product drained off miso, this dark brown
liquid is typically used in Asian dishes. Tamari soy sauce is a by-product of miso
without added grains.
Tempeh: A popular Indonesian food made by combining soybean with either rice
or millet and a mold culture for 24 hours. It’s a hearty, chewy, meat-like cake that
can be grilled as a burger or added to a main dish.
Natto: A sticky, pasty-textured, slightly sweet-tasting soy ferment, eaten for
breakfast or dinner as a topping on rice or added to vegetable dishes.
Miso A rich, salty, fermented paste (made from salted soybeans alone or mixed
with grains such as wheat, barley, and rice) that is cultured and aged.
Fermented tofu: First a tough-textured tofu is made from cooked pur? soybeans
processed into a custard-like cake; it is then fermented to make a white, creamy
food resembling semi-soft cheese.
Fermented soymilk or yogurt: Made from soymilk that is fermented by probiotic
bacteria, it can be used as a dessert or to make sour cream, cream cheese, or a
form of ice cream.
Fermented soy powder: A whole-food, bacteria-fermented powder used in
nutritional shakes, bars, or in baking, with all the nutritional value of traditional
fermented soy.

47. Fermented Soy Bean Paste