soy sauce (shoyu)
ingredient / ingredient-shoyu
醤油
Soy sauce (shoyu) is a traditional Japanese liquid seasoning made chiefly from soybeans, wheat, and salt through koji making with Aspergillus oryzae or related molds, followed by lactic-bacterial and yeast fermentation and aging. Pressing the matured moromi yields namaage soy sauce; of this, soy sauce disinfected only by fine filtration is called raw soy sauce (nama), while heat-pasteurized soy sauce is called heat-treated soy sauce (hiire).
Photographs (captions in Japanese)
Dark soy sauce (koikuchi shoyu) poured from a soy sauce dispenser into a small dish.
Shown: Fermented seasoning made mainly from Glycine max (soybean)Part / state: Dark soy sauce (koikuchi shoyu, liquid)
Photo: サフィル / CC BY-SA 4.0 / original image / ledger's original image
Scope and provenance of the photo
Identification: Identified as labelled in the source. Based on the description on the file page, "dark soy sauce poured from a soy sauce dispenser into a teshio-zara".
Image shown: The original from Wikimedia Commons, reduced to 2400 px on the long side. No cropping or color changes. For display, a WebP capped at 1200 px wide is served; the ledger's original image can be checked from the link above.
On this page (8 sections)
Reading the bitterness
Soy sauce (「醤油」; shoyu) is a traditional Japanese seasoning made mainly from soybeans, wheat, and salt through fermentation by koji mold, lactic acid bacteria, and yeast. A 2017 sensory study compares the characteristics of commercial raw soy sauce (nama) and heat-treated soy sauce (hiire) against this basic description of ingredients and fermenting microorganisms.
Soy sauce bitterness is considered to arise from bitter amino acids such as isoleucine and from peptides. Based on that understanding, the 2017 study used the concentration of phenylalanine, a bitter amino acid, as a quantitative indicator of bitterness. This was background information based on prior literature cited by the study, however; the study itself did not newly isolate or identify bitter peptides.
A 1992 study prepared glycoside fractions from raw soybeans, koji, soy sauce, and soy sauce lees and compared them by TLC. It detected no glycosides such as saponins or isoflavones in soy sauce itself, with most transferring to the lees. A band corresponding to soyasapogenol B was detected only in koji and lees, leading the authors to infer that enzymes breaking down soybean group B saponins to aglycones are produced during koji making. Calculated from ingredient proportions and lees yield, breakdown rates were 68.7% for Bb and 33.0% for Ab; the total concentration of group B saponins in lees was about 2.5 times that in raw soybeans.
Sources for this overview
定量的記述分析法による市販の生しょうゆと火入れしょうゆの評価および日本のしょうゆの特徴の体系化
Checked for this overview: Checked the description of soy sauce's main ingredients and fermentation microorganisms. / Checked the second-hand account attributing bitterness to amino acids and peptides.
大豆不快味成分と発酵食品―大豆サポニン・イソフラボン成分を中心に―
Checked for this overview: Checked transfer of glycosides to the lees and the breakdown rates.
Other names: しょうゆ (ja)
Follow the connections
soy sauce (shoyu) →— bitterness is attributed …→ bitter peptides
soyasaponin group B →is excluded from→ soy sauce (shoyu)
soy sauce (shoyu) →is prepared from→ soybean
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (2)
Scope: Commercial soy sauce (background description in Imamura & Katayama 2017's examination of the validity of sensory-evaluation terms)
Note: In the process of selecting a quantitative indicator for sensory evaluation, Imamura & Katayama (2017) state 「しょうゆの苦味は，isoleucineなどの苦味を呈するアミノ酸やペプチド類に起因すると考えられている」 (in translation: "the source states that soy sauce's bitterness is attributed to bitter-tasting amino acids such as isoleucine, and to peptides"), and analyse, as indicators of bitterness, 9 bitter amino acids (phenylalanine, arginine, isoleucine, valine, leucine, methionine, histidine, tyrosine and lysine) and melanoidins indexed by the colour number. This description is a background explanation based on a prior source cited by the same paper (reference 23, a secondary citation whose original was not checked), and the same paper itself does not newly isolate or identify a bitter peptide.
Show data
ingredient-shoyu —has_bitterness_attributed_to→ compound-class-bitter-peptidesScope: The glycoside fraction of commercial soy sauce (TLC analysis)
Note: Kudo et al. (1992) prepared glycoside fractions from raw soybean, finished koji, soy sauce, and soy sauce lees, and compared them by TLC, showing that no glycoside components (saponins, isoflavones) are detected in the soy sauce itself, with most of them moving into the soy sauce lees. Because a band corresponding to soyasapogenol B was detected only in the finished koji and the soy sauce lees, it is inferred that an enzyme that breaks down the soybean saponin B group into its aglycone is produced during the koji-making process. The total group B saponin concentration in the soy sauce lees was about 2.5 times that of the raw soybean, and the degradation rate over the course of brewing was calculated at 68.7% for Bb and 33.0% for Ab.
Show data
compound-class-soyasaponin-group-b —is_excluded_from→ ingredient-shoyuHow processing and cooking change it (1)
Note: Imamura and Katayama (2017): 「しょうゆは大豆，小麦，食塩を主な原材料とし，麹菌，乳酸菌，酵母による発酵を経て作られる日本の伝統的な調味料である」 (in translation: "Soy sauce is a traditional Japanese seasoning made mainly from soybeans, wheat, and salt and fermented with koji mold, lactic acid bacteria, and yeast").
Show data
ingredient-shoyu —is_prepared_from→ organism-glycine-max