Soy sauce is a flavor enhancer

SOY SAUCE
IS
A FLAVOR ENHANCER
By
Kevin KF Ng, MD, PhD.
Former Associate Professor of Medicine
Division of Clinical Pharmacology
University of Miami, Miami, FL., USA
Email: kevinng68@gmail.com
A Slide Presentation for HealthCare Providers Jan 2023

Presentation Outline
▪ History
▪ What is soy sauce
▪ Manufacture
▪ Composition
▪ Varieties
▪ Aroma, taste, flavor
▪ Scientific studies
▪ Summary
Chinese soy sauce Japanese soy sauce

What is soy sauce?
▪ The name “soy” came from the Latin word “Salsas”, which means ‘salted’. Sauces
are liquid or semi-liquid, hot or cold mixtures which are added to meat, poultry,
fish, vegetables and desserts to give moisture or richness, to garnish or to
enhance the appearance and the flavor.
▪ A sauce is an aromatic, flavorful liquid (or semi liquid) which forms one of the
basic part of a dish, increasing the taste, moisture, appearance and color of the
dish.
▪ A sauce may be thick or thin and may be strained or un-passed with visible
ingredients, which can be served with a hot or cold dish, as a part of the dish or
as an accompaniment separately with the dish.
Chinese soy sauce Japanese soy sauce Indonesian sweet soy

▪ HISTORY
▪ CLASSIFICATION
▪ MANUFACTURE

History of soy sauce
https://www.soysauce.or.jp/en/the-history-of-soy-sauce

The origin of soy sauce
• China 500 BCE
• Japan 1254 CE
• Netherlands
• Southeast Asia
●
●
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● 1688 CE

Top soy sauce exporting countries
• China
• Japan
• USA
• Netherlands
• Hong Kong
• Thailand
• Germany
• Taiwan
• UK
• Philippines.
●
●
●
●
●
●
● ●
●
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Exporting countries

Classification of Chinese and Japanese soy sauce
Chinese soy sauce
▪ Dark soy sauce (high-salt liquid-state
fermentation soy sauce )
▪ Light soy sauce (low-salt solid-state
fermentation soy sauce )
▪ Sweet soy sauce
Japanese soy sauce
▪ koikuchi shoyu (dark soy sauce)
▪ usukuchi shoyu (light soy sauce)
▪ shiro shoyu (white soy sauce: low soy)
▪ tamari shoyu (low wheat)
▪ saishikomi shoyu (twice-brewed soy
sauce).

Composition of Original Chinese and Japanese soy sauce
• Chinese soy sauce (jiangyou) is primarily made of soybeans, and it’s darker in color
and saltier in flavor than Japanese soy sauce and not as sweet.
• Japanese soy sauce (shoyu) is made with a nearly equal blend of soybeans and
wheat: the starch in the wheat adds a characteristic sweetness and rounder flavor,
and a higher alcohol content and alcohol-derived aromas.

Soy sauce variations by country
▪ Burmese
▪ Chinese: two classes: brewed or blended
▪ Filipino
▪ Hawaiian
▪ Indonesian
▪ Japanese
▪ Korean
▪ Malaysian and Singaporean
▪ Sri Lankan
▪ Taiwanese
▪ Thai
▪ Vietnamese
https://en.wikipedia.org/wiki/Soy_sauce

Difference between light and dark soy sauce
https://theplantbasedwok.com/a-guide-to-chinese-soy-sauce/
The main difference between light and dark soy sauce:
• Light soy sauce (7.2% sodium) – adds salt to a dish but doesn't stain noodles a deep
mahogany color nor does it add much “soy flavor”
• Dark soy sauce (9.3% sodium) – more intense in flavor and saltiness, noodles become a lovely
dark color

Soy sauce manufacturing processes
Manufacture
Fermentation process Chemical process
(Acid hydrolysis)
Semi-fermentation method
Hydrolyzed proteins
+
Partial fermentation with wheat mixture

Raw Ingredients of soy sauce
▪ Soy sauce is made using essentially five basic raw ingredients:
1. soybeans/soybean flakes (as the main protein source)
2. wheat/wheat flour (as the main carbohydrate source)
3. salt
4. water
5. Aspergillus oryzae/Aspergillus sojae, salt-tolerant yeast and lactic acid
bacteria.
Chinese soy sauce Japanese soy sauce
Soy : Wheat ratio Soy : Wheat ratio
100 : 0
80 : 20 50 : 50
70 : 30

Raw components of soy sauce
Soybeans Wheat

Micro-organisms used in the fermentation of soy sauce (1984)
(1) Aspergillus oryzae or Aspergillus sojae (fungus)
(a) Do not produce mycotoxins;
(b) possess high proteolytic, amylolytic, and macerating enzyme
levels.
(2) Pediococcus halophilus (bacteria)
(a) Produce lactic acid and other useful organic acids in a high
concentration of salt brine;
(b) do not possess tyrosine decarboxylase and histidine
decarboxylase.
(3) Saccharomyces rouxii (yeast)
Produce alcohol and excellent flavor substances in a high salt
concentration brine.
(4) Candida (Torulopsis) versatilis and C. etchellsii (fungus)
Produce excellent flavor substances in a high salt concentration
brine.
https://www.sciencedirect.com/science/article/abs/pii/0740002084900674#:~:text
=Micro%2Dorganisms%20related%20to%20soy,Candida%20(Torulopsis)%20etchellsii)

Flowcharts of key stages in production of traditionally fermented soy sauce
with variations [J, Japanese-type; C, Chinese-type; T, Tamari] (2020)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581291/
fermented soy sauce

fermented soy sauce acid-hydrolyzed soy sauce
Flowcharts of key stages in production of traditionally fermented soy sauce
(A) with variations [J, Japanese-type; C, Chinese-type; T, Tamari] and
(B) acid-hydrolyzed soy sauce (2020)

Variations in soy sauces by regions and by countries
Chinese soy sauce Japanese soy sauce Indonesian sweet soy

Soy sauce made by chemical hydrolysis
Hydrolyzed soy protein

Flavor enhancers may be added to soy sauce
▪ Oyster extract
▪ Fish extract
▪ Squid extract
▪ Abalone extract
▪ Mushroom extract
▪ Herbs and spices
▪ Monosodium glutamate
▪ Hydrolyzed vegetable protein
▪ Synthetic flavor enhancing agents

CHARACTERISTICS OF SOY SAUCE
▪ AROMA
▪ TASTE
▪ FLAVOR
DARK VS LIGHT SOY SAUCE

Aromas of soy sauce
▪ Soy sauce has over 300 fragrant components.
▪ Some of aroma include those from:
▪ Roses
▪ Hyacinths
▪ Peaches
▪ Apples
▪ Almonds
▪ Coffee
▪ Vanilla

Tastes of soy sauce
https://www.soysauce.or.jp/en/the-secrets-of-delicious-soy-sauce

Flavors of soy sauce
https://www.soysauce.or.jp/en/the-secrets-of-delicious-soy-sauce
Flavor

Main Categories of Soy Sauces and Their Description (2020)

Nutrient composition of soy sauce
https://www.eater.com/23053390/guide-to-buying-chinese-soy-sauce

Macronutrients in soy sauce
▪ Soy sauce is low in Calories, very low in Saturated
Fat and Cholesterol but high in protein.
▪ Because soy sauce is consumed in such small
amounts, it is not a good source of vitamins or
minerals.
▪ The only significant micronutrient is sodium. A
one-tablespoon serving provides 879 milligrams of
sodium, according to USDA .

Sodium levels (mg/100g) in 8 different brands of soy sauce
(2016)
https://www.researchgate.net/figure/Sodium-levels-in-8-
different-brands-of-Chinese-soy-sauce_tbl2_305953422

Organic Dark Soy Sauce: % Daily value
https://asianorganicsfood.com/products/organic-dark-soy-sauce/

Difference between Light soy sauce and Dark soy sauce
Light Soy sauce
▪ Salty content 7.2%
▪ Thin and watery
▪ Does not color noodles
Dark soy sauce
▪ Salt content 9.3%
▪ Dark and thicker
▪ More flavor
▪ DOES COLOR NOODLES
▪

BIOACTIVE COMPOUNDS
▪ AROMA
▪ TASTE
▪ FLAVOR

Chemical and Sensory Characteristics of Soy Sauce:
A Review (2020)
▪ Soy sauce is a fermented product, and its flavor is a complex mixture of individual
senses which, in combination, create a strong palatable condiment for many
Eastern and Western dishes.
▪ Aroma is characterized by caramel-like, floral, smoky, malty, and cooked potato-
like odors. Aroma-active volatiles are chemically diverse including acids, alcohols,
aldehydes, esters, furanones, pyrazines, and S-compounds
▪ Taste is dominated by umami and salty sensations. Free amino acids, nucleotides,
and small peptides are among the most important taste-active compounds.
▪ The origin of all compounds relates to both the raw ingredients and starter cultures
used as well as the parameters applied during production. It is the beginning to
develop innovative studies to combine different analytical platforms and
chemometric analysis to link flavor attributes to chemical composition.
https://pubs.acs.org/doi/10.1021/acs.jafc.0c04274

What is the aroma of soy sauce?
▪ Aroma is characterized by:
▪ Caramel-like odor
▪ Floral odor
▪ Smoky odor
▪ Malty odor
▪ cooked potato-like odor
▪ Aroma-active volatiles are chemically diverse including:
▪ Acids
▪ Alcohols
▪ Aldehydes
▪ Esters
▪ Furanones
▪ Pyrazines
▪ S-compounds

Aroma induced by Volatile Compounds in Different Types of Soy Sauces
(2020)
▪ Malty
▪ Caramel-like aroma
▪ Cooked aroma-like aroma
▪ Loral
▪ Alcoholic
▪ Sour
▪ Smoky
▪ Spic-like, Fenugreek-like
▪ Fruity
▪ Roasted, nutty and mushroom-like

What is the taste of soy sauce?
▪ Kokumi ? Sixth taste

Taste-active compounds in soy sauce
(>300 compounds)
Non-volatile compounds
▪ Free amino acids
▪ Peptides
▪ Synthetic peptides
▪ Nucleotides
▪ Free fatty acids
▪ Neutral lipids
▪ Phospholipids
▪ Organic acids
▪ Polyphenols
Volatile compounds
▪ acids
▪ alcohol
▪ aldehydes
▪ esters
▪ furanones
▪ pyrazines
▪ Sulfur-compounds
Adapted from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581291/

Compounds which have been reported to be linked to
taste attributes (2020)
Free amino acids Peptides Nucleotides Organic acids Not tested
• Free fatty acids
• Neutral lipids
• Phospholipids
• Polyphenols

What is the flavor in soy sauce?

Chemical composition of soy sauce
▪ The chemical composition of soy sauce can be affected easily by raw materials, fermentation methodologies, fermenting molds and strains, and post-
fermentation treatments.[37] Although the formation mechanism of chemical composition in soy sauce is complex,
▪ It has been widely accepted
▪ that free amino acids,
▪ water-soluble peptides and
▪ Maillard reaction products in soy sauce are considered as essential chemical composition and to provide core sensory effects.
▪ The primary fermentation of lactic-acid-fermenting halophiles lowers the pH of the moromi, and this directly results in the acidic pH range
(4.4–5.4) of soy sauce products. The secondary fermentation conducted by heterofermentative microbes provides soy sauce with a wide
range of flavor and odorant compounds by breaking down macro-nutrients. Soy proteins and grain proteins are hydrolyzed into short
peptide chains and free amino acids, which adds umami to the product.
▪ Based on the result of free amino acid analysis, the most abundant amino acids in Chinese soy sauce product are
▪ glutamic acid,
▪ aspartic acid,
▪ alanine and
▪ leucine
▪ Starch is hydrolyzed into simple sugars which contribute to the sweet flavor in soy sauce. Legume fats may also be decomposed into short
chain fatty acids, and the interactions among lipids and other macronutrients also result in a richer flavor in the final product. Non-
enzymatic browning also contributes significantly to the development of the properties of soy sauce.
▪ The hydrolysis of proteins and large carbohydrates also provides free amino acids and simple sugars as reagents for the Maillard reaction.
▪ Soy sauce may contain more than 1% alcohol.
https://en.wikipedia.org/wiki/Soy_sauce

Characteristics of Soy Sauce
▪ The difference between brewed and non-brewed soy sauce go far beyond production methods. Brewed
soy sauce has almost 300 identifiable constituents amongst ingredients in food products.
▪ Salt: 12.0% to 18.0% (w/v).
▪ Amino Acids: Enzymes convert the soybean protein into amino acids (such as glutamic acid, aspartic
acid, lysine, alanine, glycine and tryptophan) and peptides
▪ Sugar: The moromi enzymes also convert the wheat starch into sugars. Although glucose is the primary
sugar, more that ten others have been isolated
▪ Color: Some of the amino acids and the sugar subsequently undergo a Maillard reaction during
fermentation to develop the sauce’s characteristic reddish-brown color
▪ Acids: art of the alcohols and an additional portion of the sugar react to produce acids. Finished soy
sauce has a pH of about 4.8 and contains around 1.0% lactic acid
▪ Aromatic Esters: Ethanol, once again, is critical because it combines with some of these organic acids to
form esters
▪ Post Fermentation Development: The heat of pasteurisation further develops large numbers of
compounds that contribute to aroma and flavor. At the same time, this step deepens the sauce’s colour
https://kikkoman.com.au/blog/characteristics-of-soy-sauce/

GC-MS volatile profiles of two soy sauce samples
extracted by SBSE (stir-bar sorptive extraction) 2020

Perceptions of aroma and taste induced by
soy sauce (2020)
Aroma Taste
1. Caramel, sweet
2. Spice, fennugreek
3. Cooked potato
4. Fruity, sweet
5. Floral
6. Malty, Almond
7. Sulfur,Cooked vegetables
8. Nutty, grassy
9. Spicy
10. Smoky, Burnt
11. Meaty
12. Cheese, Soup
13. Honey, Sweet
14. Mushsroom
15. Roasty, Popcorn
1. Sweet
2. Umami
3. Kokumi
4. Salty
5. Bitter
6. Sour
7. Astringent

Volatile and non-volatile chemical compounds
in soy sauce (2020)
Volatile aromatic compounds
▪ Acids (15)
▪ Alcohols (8)
▪ Aldehydes (9)
▪ Esters (15)
▪ Furanones (17)
▪ Ketones (8)
▪ Phenols (8)
▪ Pyrazine (13)
▪ Sulfur-containing compounds (11)
▪ Others (8)
Non-volatile taste stimulants
▪ Amino acids (14)
▪ Peptides (2)
▪ Kokumi peptide (1)
▪ Nucleotides (3)
▪ Sodium chloride (1)
▪ Organic acids (7)
▪ Phenolic compounds not tested
▪ Neutral lipids not tested
▪ Fatty acids not tested
▪ Phospholipids not tested
Total 112 Total 28

Soy sauce flavor wheel (2020)

SCIENTIFIC STUDIES
▪ PRECLINICAL
▪ CLINICAL

The identification of antioxidants in dark soy sauce (2007)
▪ Soy sauce is a traditional fermented seasoning in Asian countries, that has high
antioxidant activity in vitro and some antioxidant activity in vivo. We attempted to
identify the major antioxidants present, using the 2,2'-azinobis(3-
ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay as a guide.
▪ 3-Hydroxy-2-methyl-4H-pyran-4-one (maltol) was one of several active compounds
found in an ethyl acetate extract of dark soy sauce (DSS) and was present at
millimolar concentrations in DSS.
▪ However, most of the antioxidant activity was present in colored fractions, two of
which (CP1 and CP2) were obtained by gel filtration chromatography. Their structural
characteristics based on nuclear magnetic resonance (NMR) and electrospray-
ionization time-of-flight mass spectrometry (ESI-TOF-MS) analysis suggest that
carbohydrate-containing pigments such as melanoidins are the major contributors
to the high antioxidant capacity of DSS.
https://pubmed.ncbi.nlm.nih.gov/17454130/

Identification of antioxidants in dark soy sauce. (2011)
▪ Soy sauce is a traditional fermented seasoning in Asian countries, that has high
antioxidant activity in vitro and some antioxidant activity in vivo.
▪ We attempted to identify the major antioxidants present, using the 2,2?-azinobis(3-
ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay as a guide.
▪ 3-Hydroxy-2-methyl-4H-pyran-4-one (maltol) was one of several active compounds
found in an ethyl acetate extract of dark soy sauce (DSS) and was present at millimolar
concentrations in DSS. However, most of the antioxidant activity was present in colored
fractions, two of which (CP1 and CP2) were obtained by gel filtration chromatography.
Their structural characteristics based on nuclear magnetic resonance (NMR) and
electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) analysis suggest
that carbohydrate-containing pigments such as melanoidins are the major contributors
to the high antioxidant capacity of DSS.
▪ In vitro, maltol, CP1 and CP2 can protect against hypochlorous acid (HOCl)-mediated
DNA damage dose-dependently.
▪ Furthermore, dark soy sauce potentially inhibits the growth of colon cancer HT 29 cells
at high concentrations, while it decreases the up-regulation of cyclooxygenase-2 (COX-
2) expression in LPS (lipopolysaccharide) -induced HT 29 cells at low concentrations
https://scholarbank.nus.edu.sg/handle/10635/22103?
mode=full

Antioxidants in Dark Soy Sauce Have Dramatic Effect (2006)
https://www.naturalproductsinsider.com/specialty-nutrients/antioxidants-dark-soy-sauce-have-dramatic-effect
▪ The researchers divided 24 volunteers into two groups which were given either
rice with 30 mL of dark soy sauce or plain rice with added caramel coloring
(placebo). After three days, the groups switched.
▪ Analysis showed that the dark soy sauce had a rapid antioxidant effect--on
average, 10 times greater than red wine and 150 times greater than vitamins C
and E--with an accompanying improved vascular effect. The researchers did not
note any effect on blood pressure resulting from the sodium content of the soy
sauce.

Antihypertensive and Natriuretic Effects of Less Sodium Soy Sauce Containing
γ-Aminobutyric Acid in Spontaneously Hypertensive Rats (2014)
▪ We investigated the mechanism of the antihypertensive effect of less-sodium soy sauce
containing -aminobutyric acid (GABA) in spontaneously hypertensive rats (SHRs).
▪ When SHRs were given a diet with less-sodium soy sauce containing GABA (GABA-rich
soy sauce group) for 6 weeks, the systolic blood pressure decreased as compared with
that in rats fed diets with less sodium soy sauce or a solution of salt.
▪ Renal sympathetic nerve activity (RSNA) and positive Na balance were reduced, and the
urinary Na excretion tended to increase in the GABA-rich soy sauce group.
▪ Vascular hypertrophy of the thoracic aorta and the coronary and renal interlobular
arteries tended to reduce in the GABA-rich soy sauce group.
▪ These results suggest that inhibition of Na retention by natriuresis, as a result of
inhibition of RSNA by the GABA in the soy sauce contributed to the antihypertensive
effect of GABA in the SHRs.
https://www.tandfonline.com/doi/pdf/10.1271/bbb.60424

Association between the Portion Sizes of Traditional Japanese Soy Sauce
and Miso and Blood Pressure:
Cross-Sectional Study Using National Health and Nutrition Survey, 2012–2016 Data (2018)
▪ While previous studies have reported the association between food portion size and health outcomes, the
association between food seasonings and blood pressure (BP) has not been clarified.
▪ This study aimed to investigate the association between the portion sizes of traditional Japanese
seasonings and BP. Data on 25,738 Japanese participants (10,154 men and 15,584 women) aged ≥20
years registered in the 2012–2016 National Health and Nutrition Survey (NHNS) were used for this cross-
sectional study.
▪ The portion sizes of soy sauce or miso were calculated from the reported weight of soy sauce or miso,
and the number of dishes. Regression models were used to estimate BP and prevalence of hypertension,
and their 95% confidence intervals according to the portion size of soy sauce or miso.
▪ We did not observe an association between the portion sizes of soy sauce or miso and BP. A larger
portion size of soy sauce or miso was associated with a higher prevalence of hypertension in the crude
model among women, but no significant associations were observed in the multivariate model in both
sexes.
▪ Our findings suggest that the portion sizes of soy sauce or miso are not associated with BP among
Japanese adults.
▪ Keywords: Japanese seasoning, blood pressure, hypertension, National Health and Nutrition Survey,
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC631606
2/

Chinese Traditional Fermented Soy Sauce protects High-Fat and High-Salt Diet-Induced
Hypertension in Rats by Improving
Adipogenesis and Renin-Angiotensin-Aldosterone System Activity (2021)
Renin-angiotensin-aldosterone relative levels in serum.
(A) Renin level of serum
(B) Ang II level of serum
(C) ACE level of serum
(D) Aldosterone level of serum
ND: normal diet
HD: high-fat diet;
HDS: high-fat diet + saline;
HDCTS: high-fat diet + Chinese traditional soy sauce.
https://www.mdpi.com/2311-5637/7/2/52

Black soy peptide supplementation lowered
blood pressure and oxidative stress:
a randomized controlled trial (2013)
https://www.nature.com/articles/hr201379/figures/1
SBP DBP Pulse pressure

Usage of soy sauce
▪ Soy sauce can be added directly to food and is used as a dip or salt flavor in
cooking.
▪ It is often eaten with rice, noodles, and sushi or sashimi, or can also be mixed with
ground wasabi for dipping.
▪ Bottles of soy sauce for salty seasoning of various foods are common on restaurant
tables in many countries.
▪ Finished soy sauce has a pH of about 4.8 and contains around 1.0% lactic acid.
This contributes a refined, rounded tartness that is thought to be one of the keys to
good soy sauce flavor.
▪ In addition to lactic acid, more than ten other organic acids may also be identified.
https://kikkoman.com.au/blog/characteristics-of-soy-
sauce/

Potential Health Risks of Soy Sauce
▪ Allergies (gluten from wheat)
▪ High sodium content may lead to high blood pressure
▪ Presence of Unhealthy Additives
▪ Commercial soy sauce contains a high amount of phytates that block the absorption of minerals in your body.
▪ Monosodium glutamate (MSG) is a significant component of taste enhancer in soy sauce, Several studies
revealed that MSG has toxic effect on fetal development/fetus, children's, adolescent, and adults. Physiological
complication associated with MSG toxicity are hypertension, obesity, gastrointestinal tract troubles, and
impairment of function of brain, nervous system, reproductive, and endocrine system
▪ In 2001, the United Kingdom Food Standards Agency found in testing various soy sauces
manufactured in mainland China, Taiwan, Hong Kong, and Thailand (made from hydrolyzed soy
protein, rather than being naturally fermented) that 22% of tested samples contained a chemical
carcinogen named 3-MCPD (3-monochloropropane-1,2-diol) at levels considerably higher than those
deemed safe by the EU. About two-thirds of these samples also contained a second carcinogenic
chemical named 1,3-DCP (1,3-dichloropropane-2-ol) which experts advise should not be present at
any levels in food.
https://pubmed.ncbi.nlm.nih.gov/30273089/#:~:text=Several%20studies%20reveal
ed%20that%20MSG,%2C%20reproductive%2C%20and%20endocrine%20system.

Summary
▪ Soy sauce originated in China 500 BCE. It was modified by the
addition of wheat in Japan in 1254 CE. The Dutch introduced it
to Southeast Asia and the Netherlands in 1688 CE.
▪ Soy sauce can be classified into Chinese and Japanese soy
sauce with variation according to the duration of fermentation,
salt content and the selection of molds and yeasts.
▪ Soy sauce is low in Calories, carbohydrates, fat and cholesterol
but high in protein and Sodium chloride.
▪ The fermentation of soybean and wheat results in more than 300
bioactive compounds which give rise to the characteristic aroma,
taste and flavor of soy sauce.
▪ Soy sauce is relatively safe except the allergy caused by gluten
from the sauce made with wheat.

Soy sauce is a flavor enhancer

Soy sauce is a flavor enhancer

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