Compounds In Soy Sauce Research Articles

Transcriptome and Proteome Expression Analysis of the Metabolism of Amino Acids by the Fungus Aspergillus oryzae in Fermented Soy Sauce.

Amino acids comprise the majority of the flavor compounds in soy sauce. A portion of these amino acids are formed from the biosynthesis and metabolism of the fungus Aspergillus oryzae; however, the metabolic pathways leading to the formation of these amino acids in A. oryzae remain largely unknown. We sequenced the transcriptomes of A. oryzae 100-8 and A. oryzae 3.042 under similar soy sauce fermentation conditions. 2D gel electrophoresis was also used to find some differences in protein expression. We found that many amino acid hydrolases (endopeptidases, aminopeptidases, and X-pro-dipeptidyl aminopeptidase) were expressed at much higher levels (mostly greater than double) in A. oryzae 100-8 than in A. oryzae 3.042. Our results indicated that glutamate dehydrogenase may activate the metabolism of amino acids. We also found that the expression levels of some genes changed simultaneously in the metabolic pathways of tyrosine and leucine and that these conserved genes may modulate the function of the metabolic pathway. Such variation in the metabolic pathways of amino acids is important as it can significantly alter the flavor of fermented soy sauce.

Comparative Volatile Profiles in Soy Sauce According to Inoculated Microorganisms

We compared the volatile profiles in soy sauce according to inoculation with Tetragenococcus halophilus and/or Zygosaccharomyces rouxii. Totals of 107 and 81 volatiles were respectively identified by using solid-phase microextraction and solvent extraction. The various volatile compounds identified included acids, aldehydes, esters, ketones, furans and furan derivatives, and phenols. The major volatiles in the samples treated with T. halophilus were acetic acid, formic acid, benzaldehyde, methyl acetate, ethyl 2-hydroxypropanoate, 2-hydroxy-3-methyl-2-cyclopenten-1-one, and 4-hydroxy-3-methoxybenzaldehyde, while those in the samples inoculated with Z. rouxii were mainly ethanol, acetaldehyde, ethyl propanoate, 2/3-methylbutanol, 1-butanol, 2-phenylethanol, ethyl 2-methylpropanoate, and 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone. The results indicate that T. halophilus produced significant acid compounds and could affect the Z. rouxii activity, supporting the notion that yeasts and lactic acid bacteria respectively have different metabolic pathways of alcoholic fermentation and lactic acid fermentation, and produce different dominant volatile compounds in soy sauce.

Co-culturing of Pichia guilliermondii enhanced volatile flavor compound formation by Zygosaccharomyces rouxii in the model system of Thai soy sauce fermentation

The roles of salt-tolerant yeasts such as Zygosaccharomyces rouxii, Candida versatilis, and Candida etchellsii in the production of volatile flavor compounds (VFCs) in soy sauce fermentation have been well documented. However, the knowledge of VFC production by other salt-tolerant yeasts is still limited. In this work, the roles of Z. rouxii and Pichia guilliermondii strains in VFC production were investigated in moromi medium as a model system for soy sauce fermentation. Inoculation of a single culture of either Z. rouxii or P. guilliermondii as well as co-cultures of these two yeasts into moromi medium showed increased numbers of viable yeast at around 0.7 to 1.9 log CFU/mL after 7days of cultivation at 30°C. During cultivation, both single and co-cultures displayed survival over a 7-day time period, compared with the controls (no culture added). Overall, yeast inoculation enhanced the production of VFCs in the moromi media with higher amounts of ethanol, alcohols, furanones, esters, aldehyde, acid, pyrone and phenols, known as important characteristic flavor compounds in soy sauce. Moreover, the co-culture produced more alcohols, furanones, esters, maltol and benzoic acid than the single culture of Z. rouxii.

Effect of Halotolerant Starter Microorganisms on Chemical Characteristics of Fermented Chum Salmon (Oncorhynchus keta) Sauce

Chum salmon sauce mash was inoculated with barley koji (barley steamed and molded with Aspergillus oryzae ) and halotolerant microorganisms (HTMs), Zygosaccharomyces rouxii , Candida versatilis , and Tetragenococcus halophilus , in nine different combinations under non-aseptic conditions similar to the industrial fish sauce production and fermented at 35 +/- 2.5 degrees C for 84 days. The changes in the chemical components, color, and sensory properties during fermentation were investigated. Free amino acid content was increased, and the browning of fish sauce was enhanced by the usage of barley koji during fermentation. The halotolerant yeast (HTY) produced ethanol and repressed the browning by consumption of reducing sugar. Inoculated Z. rouxii in the fish sauce mash produced 2-phenylethanol (2-PE) and 4-hydoxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF), and C. versatilis in the fish sauce mash produced 4-ethylguaiacol (4-EG), known as characteristic flavor compounds in soy sauce, adding soy-sauce-like flavor to the fish sauce. Thus, inoculation of HTMs and barley koji was effective for conferring the soy-sauce-like flavor and increasing free amino acid and ethanol contents in fish sauce product.

Improvement of soy‐sauce flavour by genome shuffling in Candida versatilis to improve salt stress resistance

SummaryGenome shuffling of Candida versatilis was applied to improve the soy‐sauce flavour by further increasing salt stress resistance. A mutant S3‐5, with a stronger resistance to salt, was isolated after three rounds of genome shuffling. It is found that S3‐5 improved stress tolerance to higher potassium chloride and lithium chloride. S3‐5 not only grew well in the YPD (peptone, yeast extract and dextrose) medium containing high concentrations of sodium chloride with various pH values, but also exhibited improvement of growth ability in soy‐sauce medium. The main aroma compounds in soy sauce were distinctly improved. Notably, S3‐5 produced about 2.78 times as much ethanol as the control strain. Another important aroma compound, 4‐hydroxy‐2 (or 5)‐ethyl‐5 (or 2)‐methyl‐3 (2H)‐furanone (HEMF) was enhanced by up to 80%. Meanwhile, S3‐5 accelerated flavour formation of soy sauce thus decreasing the total time required for the aroma development.

Rapid determination of volatile flavor components in soy sauce using head space solid-phase microextraction and gas chromatography-mass spectrometry

A rapid and simple method was developed for the determination of volatile flavor compounds (VFCs) in soy sauce by head space solid-phase microextraction (HS-SPME) coupled to capillary gas chromatography-mass spectrometry (GC-MS). Five types of SPME fibers, including 85 microm PA, 100 microm PDMS, 75 microm CAR/PDMS, 65 microm PDMS/DVB, 50 microm DVB/CAR/PDMS were investigated. Three parameters for HS-SPME in terms of adsorption time, salt concentration, and extraction temperature were optimized. Adsorption time tested in this study were 20, 40 and 60 minutes; the salt concentrations were 180, 210, 250, 270 and 300 g/L; and extraction temperatures were 25, 35, 45, 55 and 65 degrees C. The concentrations of the compounds were calculated based on their relative peak areas to the internal standard of 2-octanol. An 85 microm PA fiber, adsorption time of 40 min, a temperature of 45 degrees C and NaCl concentration of 250 g/L were selected as th optimum conditions. This optimized method was applied to evaluate a real sample. As a result, 97 compounds in a soy sauce sample were isolated and identified successfully. The results showed that alcohols, carboxylic acids, esters and phenols were the major VFCs of soy sauce. The most important groups of volatile compounds in the soy sauce sample were ethanol, hexadecanoic acid, phenylethyl alcohol and 2,3-butanediol. In addition, some oxo-compounds and heterocyclic compounds were also found. The average relative standard deviation of the relative peak area was 12.1%, and the recoveries were 79.9% - 109.6%. The method is simple, fast and accurate with high reproducibility, high sensitivity and low cost.

Evaluation of aroma compounds in soy sauce by AEDA(Aroma Extract Dilution Analysis)

Evaluation of aroma compounds in soy sauce by AEDA(Aroma Extract Dilution Analysis)

Characterization of the Key Aroma Compounds in Soy Sauce Using Approaches of Molecular Sensory Science

Application of aroma extract dilution analysis (AEDA) to the volatiles isolated from a commercial Japanese soy sauce revealed 30 odor-active compounds in the flavor dilution (FD) factor range of 8-4096, among which 2-phenylethanol showed the highest FD factor of 4096, followed by 3-(methylsulfanyl)propanal (methional), the tautomers 4-hydroxy-5-ethyl-2-methyl- and 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone (4-HEMF), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF), and 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolone), all showing FD factors of 1024. Thirteen odorants were quantified by stable isotope dilution assays, and their odor activity values (OAVs) were calculated as ratio of their concentrations and odor thresholds in water. Among them, 3-methylbutanal (malty), sotolone (seasoning-like), 4-HEMF (caramel-like), 2-methylbutanal (malty), methional (cooked potato), ethanol (alcoholic), and ethyl 2-methylpropanoate (fruity) showed the highest OAVs (>200). An aqueous model aroma mixture containing 13 odorants, which had been identified with the highest OAVs, in concentrations that occur in the soy sauce showed a good similarity with the overall aroma of the soy sauce itself. Heat treatment of the soy sauce resulted in a clear change of the overall aroma. Quantitation of selected odorants revealed a significant decrease in sotolone and, in particular, increases in 2-acetyl-1-pyrroline, 4-HDMF, and 4-HEMF induced by heating.