FERMENTED SOY PRODUCTS

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

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.

• Improved digestibility

• Enhanced nutrition

• Medicinal benefits

• Increased bioavailability

of isoflavones

Benefits of Soybean Fermentation

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.

Improved Digestibility

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.

Enhanced Nutrition

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.

Medicinal Benefits

Isoflavones (phytoestrogens naturally occurring in soy) are converted by the bacteria into their “free” or aglyconeforms for improved absorption and more effective usage within the body.

Increased bioavailability of isoflavones

1. Soy sauce

2. Tempeh

3. Natto

4. Miso

5. Fermented tofu

6. Fermented soymilk or yogurt

7. Fermented soy powder

Popular Fermented Whole Soy Foods

SOY SAUCEA 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.

NATURAL BREWING OF SOY SAUCE

Accomplished in three distinct steps

1. Koji making

2. Brine Fermentation

3. Refining

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.

Brine FermentationThe 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.

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.

DIAGRAM OF SOY SAUCEPRODUCTION

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

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

CoolMix

Production of Soy Sauce

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. delbrueckiifollowed by a culture of S. rouxii after 1 month

Mix

Press

Soy cake Raw shoyu

Age (1 year)

Add a culture of P. halophilus or L. delbrueckiifollowed by a culture of S. rouxii after 1 month

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.

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

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Etymology

• Suggested to have been derived from the old Javanese term tumpi, a whitish food made from sago

• However, the historian Denys Lombardsuggested that it is linked to the local term tape or tapai, which means fermentation

Tempeh Production

Soybeans

Clean and wash

Soak overnight

Dehull

Boil for 30 min

Drain and Cool

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

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

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

Control of Process1. 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

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

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

Control of Process

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

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

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

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

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

Types of Miso

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

Types of Miso

Method of Miso ProductionRice

(600 kg)A. oryzae

(600 g)

Polish

Soak in water overnight

Cook in steam

Cool

Ferment

Koji

Inoculate

Soybeans (1000kg)

Salt

Clean and wash

SoakCook under

pressure

Cool

Mix

Inoculate with LAB and yeast

Ferment MISO

KOJI

Method of Miso Production

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

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 growth4. Fermentation

• Use of wide-mouthed containers• Maintenance of anaerobic condition

5. Storage at refrigerated temperature6. Pasteurization

• Short-fermented miso is pasteurized to inactivate enzymes

Major Steps in Miso Production

Control of Process1. 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.

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

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%

Fermented Whole Soybeans and Paste

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Fermented Whole Soybeans

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.

Fermented Soy Bean Paste