High-salt Liquid-state Fermentation Soy Sauce Research Articles

Characterization of Key Odorants in Soy Sauce and Their Concentration Changes during Storage

To explore the key odorants and their concentration changes in high-salt liquid-state fermentation soy sauce (HLFSS) during storage, solvent extraction coupled with solvent-assisted flavor evaporation was applied to isolate the volatiles in HLFSS, and the volatiles were analyzed by gas chromatograph-mass spectrometry-olfactory and gas chromatograph-flame ionization detector-olfactometry combined with the aroma extract dilution assay. A total of 37 odor-active compounds with flavor dilution (FD) factors ranging from 1 to 1024 were identified, and 23 aroma components with odor activity values ≥1 were considered as key odorants. Methional, 3-methylbutanoic acid, phenethyl alcohol, sotolon, 4-hydroxy-2-methyl-5-ethyl-3(2H)-furanone (HEMF), and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (HDMF) had the highest FD factors of 1024. The results of quantitative analysis through the internal standard curve showed that the concentrations of HEMF, HDMF, acetic acid, 1-hydroxy-2-butanone, acetol, and furfuryl alcohol varied greatly during storage, so these compounds might be used as the indicators to determine the shelf life of HLFSS. The recombination experiment also confirmed the important contribution of these compounds. This result will provide valuable information for understanding the flavor changes of HLFSS.

Characterization of the key aroma compounds in soy sauce by gas chromatography-mass spectrometry-olfactometry, headspace-gas chromatography-ion mobility spectrometry, odor activity value, and aroma recombination and omission analysis.

Most previous studies on volatile compounds in soy sauce were performed by gas chromatography-mass spectrometry (GC-MS). In this study, the volatile compounds of high-salt liquid-state fermentation soy sauce (HLFSS) were analyzed qualitatively and quantitatively by GC-MS and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). One hundred and seventy-four substances were detected using the two instruments, 87 by HS-GC-IMS and 127 by GC-MS. Aldehydes (26), ketones (28), esters (29), and alcohols (26) were the main compounds in HLFSS. In addition, ethyl pyruvate, (E)-2-pentenal and diethyl propanedioate were detected by HS-GC-IMS, which were previously not detected in HLFSS. Forty-eight aromatics including 34 key ones were identified by gas chromatography-olfactometry. Phenylacetaldehyde, methional, 2-methylbutanal, 1-octen-3-ol, ethyl acetate, 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)-furanone and 4-ethyl guaiacol were identified as the main aroma compounds in HLFSS by aroma recombination and omission test. This study laid foundation for developing flavor assessment standards for soy sauce.

Comparison of potent odorants in high‐salt liquid‐state fermentation soy sauce before and after sterilization

AbstractTo compare the changes of potent odorants (PO) in high‐salt liquid‐state fermentation soy sauce (HLFSS) after sterilization under 120°C for 15 s, the volatiles in HLFSS were isolated by solvent extraction combined with solvent‐assisted flavour evaporation and were analysed by gas chromatography‐mass spectrometry‐olfactometry. A total of 40 odour‐active compounds were identified, and their flavour dilution (FD) factors ranging from 1 to 4096 were determined by comparative aroma extract dilution analysis. Twenty‐four compounds with FD factors ≥8 were quantitated by establishing standard curves, and the results showed that total concentrations of alcohols and phenols were almost unchanged, those of esters, acids and pyrazines decreased and those of aldehydes and ketones increased. Based on quantitative results and thresholds in water, odour activity values (OAVs) were calculated. Eighteen compounds with OAVs ≥1 were determined as PO in HLFSS. The number of POs did not change after sterilization, and OAVs of 10 POs remained unchanged or varied very little. The significant changes in the concentrations of methional, 5‐ethyl‐4‐hydroxy‐2‐methyl‐3(2H)‐furanone, nonanal, ethyl 2‐methylbutanoate, methionol, benzeneacetaldehyde, 4‐hydroxy‐2,5‐dimethyl‐3(2H)‐furanone and 2‐ethyl‐3,5‐dimethylpyrazine after sterilization caused the obvious variations of OAVs, which made cooked potato, caramel‐like, fatty and floral notes in HLFSS change in different degrees. The results obtained have some reference value to produce SS.

Characterization of fragrant compounds in different types of high-salt liquid-state fermentation soy sauce from China

The aroma and sensory characteristics of 21 commercial high-salt liquid fermentation soy sauces (HLFSS) suitable for different edible methods were investigated by MS-based non-targeted metabolomics workflow using headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC-MS) combined with sensory evaluation. A total of 325 compounds were detected, and 60 were considered aroma-active compounds. Light soy sauce (LSS) and premium soy sauce (PSS) for direct dipping contained more alcohols and esters. Aldehydes and furans were more abundant in dark soy sauce (DSS) used for stir-frying and braising. Principal component analysis (PCA) clustered LSS, DSS, and PSS into different quadrants and distinguished HLFSS of north-south origin. In addition, orthogonal partial least squares discriminant analysis (OPLS-DA) confirmed that the difference in volatile compounds of HLFSS in northern and southern China was related to local manufacturers' use of the Japanese and Cantonese fermentation processes. Sensory evaluations showed that LSS and PSS had prominent alcoholic and fruit aromas, while DSS had firmer caramel and malty aromas. Aroma-active compounds influenced regional differences in sensory attributes. The present study results will provide a theoretical basis for broadening industrial soy sauce production with different flavors.

Combination of mutagenesis and adaptive evolution to engineer salt-tolerant and aroma-producing yeast for soy sauce fermentation.

The moromi fermentation of high-salt liquid-state fermentation (HLF) soy sauce is usually performed in high-brine solution (17-20%, w/w), which decreases the metabolic activity of aroma-producing yeast. To enhance the soy sauce flavors, increasing the salt tolerance of aroma-producing yeasts is very important for HLF soy sauce fermentation. In the present study, atmospheric and room-temperature plasma (ARTP) was first used to mutate the aroma-producing yeast Wickerhamomyces anomalus, and the salt tolerant strains were obtained by selection of synthetic medium with a sodium chloride concentration of 18% (w/w). Furthermore, adaptive laboratory evolution (ALE) was used to improve the salt tolerance of the mutant strains. The results obtained indicated that the combination use of ARTP and ALE markedly increased the NaCl tolerance of the yeast by increasing the cellular accumulation of K+ and removal of cytosolic Na+ , in addition to promoting the production of glycerin and strengthening the integrity of the cell membrane and cell wall. In soy sauce fermentation, the engineered strains improved the physicochemical parameters of HLF soy sauce compared to those produced by the wild-type strain, and the engineered strains also increased the alcohol, acid and aldehyde production, and enriched the types of esters in the soy sauce. The results of the present study indicated that the combination of ARTP mutagenesis and ALE significantly improved the salt tolerance of the aroma-producing yeast, and also enhanced the production of volatiles of HLF soy sauce. © 2021 Society of Chemical Industry.

Effect of aroma-producing yeasts in high-salt liquid-state fermentation soy sauce and the biosynthesis pathways of the dominant esters

Fermentation with excellent aroma-producing yeasts can enhance the flavour of soy sauce. In this work, Millerozyma farinosa CS2.23, Zygosaccharomyces rouxii CS2.42, and Candida parapsilosis CS2.53 were added to the high-salt liquid-state moromi to promote soy sauce fermentation. All three yeasts improved the TE of soy sauce, the highest of which reached 1.03 g/L with added CS2.42. Other quality indexes of soy sauce, including RS, TA, and AN, were not greatly affected. The volatile esters of soy sauce added to the three yeasts increased by 108.85%, 166.71%, and 113.61% compared with the control through GC-MS analysis. Obviously, CS2.42 had an excellent ability to produce esters. Studying the biosynthesis pathway of esters, CS2.42 has the best esterification ability, while CS2.53 has the advantage of alcoholysis ability. The exploration of the biosynthetic pathway of acetate and ethyl esters has laid a foundation for regulating esters in soy sauce fermentation.

Rapid Quality Discrimination and Amino Nitrogen Quantitative Evaluation of Soy Sauces by Tri-Step IR and E-nose

Despite the fact that soy sauce has been one of the most popular seasonings in Eastern Asia, rapid and holistic methods for its authentication and discrimination are still lacking. This research is sought to develop a novel method for rapid discrimination and amino nitrogen quantitative evaluation of different qualities of soy sauces (Chinese traditional fermentation soy sauce (CTFSS), Japanese traditional fermentation soy sauce (JTFSS), high-salt liquid-state fermentation soy sauce (HLFSS), and low-salt solid-state fermentation soy sauce (LSFSS)) based on tri-step infrared spectroscopy (IR) and partial least squares (PLS). Global nutrition fingerprints (saccharides, proteins, amino acids, and other compositions) of each quality soy sauce at the three levels of enhanced spectral resolution and nutrition profile variations among different soy sauces are synthetically interpreted with fast evaluation of their relative contents based on spectral peak intensity. Complementarily, electronic sensory combined with SPME-GC-MS distinguishes four species of soy sauces effective in smell with 90 discrimination indexes. Specifically, FT-IR peak intensity at about 1409 cm−1 (C–N band) exhibits regular enhancement with the increasing concentration of amino acid nitrogen. Thus, a quantitative prediction model based on IR spectra is established by PLS (R2, 0.9956; RMSEC, 0.233). It has been demonstrated that the developed method is applicable for rapid (5 min) discrimination and quantitative analysis of amino acid nitrogen in soy sauce.

Reducing the Influence of the Thermally Induced Reactions on the Determination of Aroma-Active Compounds in Soy Sauce Using SDE and GC-MS/O

A method based on simultaneous distillation extraction (SDE) coupled with gas chromatography–mass spectrometry/olfactometry (GC-MS/O) was developed for the analysis of volatile profiles in soy sauce. Its optimum operating conditions were as follows: 100 mL soy sauce plus 100 mL saturated brine; 2 h extraction using 50 mL dichloromethane. Eighty-eight volatile compounds were identified. Of these, 26 aroma-active compounds were detected by GC-O including 3-(methylthio)propanal, 2-methoxy-4-vinylphenol, 2-methoxyphenol, 2-methylbutanoic acid, 2,3-butanedione, phenylacetaldehyde, 2-ethyl-6-methylpyrazine, 3-methylbutanal, 2-methylbutanal, 3-methyl-1-butanol, and 2-methyl-1-butanol (which occurred at a high odor intensity in both high-salt liquid-state fermentation soy sauce (HLFSS) and low-salt solid-state fermentation soy sauce (LSFSS). SDE analysis of the odorless soy sauce indicated 12 volatiles (mainly Strecker aldehydes and α-dicarbonyl compounds). Thus, the proportions of these compounds (1.94–54.07 %) shown in previous GC-MS results could result from thermal degradation of non-volatile compounds in soy sauce. Especially, the contribution of 3-methylbutanal, 2-methylbutanal, phenylacetaldehyde, 3-(methylthio)propanal, and 2,3-butanedione to the aroma of soy sauce could be overestimated by conventional SDE-GC-O. With a full consideration of such limitations, this study will improve the application of SDE on aroma analysis of complex food matrix.

Characterisation of aroma profiles of commercial soy sauce by odour activity value and omission test

Twenty-seven commercial soy sauces produced through three different fermentation processes (high-salt liquid-state fermentation soy sauce, HLFSS; low-salt solid-state fermentation soy sauce, LSFSS; Koikuchi soy sauce, KSS) were examined to identify the aroma compounds and the effect of fermentation process on the flavour of the soy sauce was investigated. Results showed that 129 volatiles were identified, of which 41 aroma-active components were quantified. The types of odorants occurring in the three soy sauce groups were similar, although their intensities significantly differed. Many esters and phenols were found at relatively high intensities in KSS, whereas some volatile acids only occurred in LSFSS. Furthermore, 23 aroma compounds had average OAVs>1, among which 3-methylbutanal, ethyl acetate, 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone, 2-methylbutanal and 3-(methylthio)propanal exhibited the highest average OAVs (>100). In addition, omission tests verified the important contribution of the products resulting from amino acid catabolism to the characteristic aroma of soy sauce.

Evaluation of aroma differences between high-salt liquid-state fermentation and low-salt solid-state fermentation soy sauces from China

Two types of Chinese soy sauce, high-salt liquid-state fermentation soy sauce (HLFSS) and low-salt solid-state fermentation soy sauce (LSFSS), were used to investigate their differences in aroma profile by headspace solid-phase microextraction (HS-SPME) and gas chromatography-olfactometry/mass spectrometry (GC-O/MS). Results from descriptive sensory analysis showed that the alcoholic, cooked potato-like and caramel-like attributes were significantly higher in HLFSS, while LSFSS exhibited significantly higher sour and burnt attributes. In addition, aroma extract dilution analysis (AEDA) revealed 37 and 33 odour-active regions for HLFSS and LSFSS, respectively. Ethanol, 3-methyl-1-butanol, phenylacetaldehyde, 4-ethyl-2-methoxyphenol, 2-methoxy-4-vinylphenol and 3-(methylthio)propanal detected in HLFSS showed the highest flavour dilution (FD) factors, while 3-methylbutanal, phenylacetaldehyde and ethyl propanoate possessed the highest FD factors in LSFSS. Therefore, the traditional Chinese soy sauce HLFSS contained more complex volatiles and exhibited a richer aromatic profile compared with LSFSS.