Identification and sensory characterization of umami peptides from soy sauce and their interaction with the T1R1/T1R3 receptor

Soy sauces can be classified into three categories based on the production method used: honjozo, kongojozo (mixed-brewing, amino acid-decomposed), and kongo (mixed, amino acid-decomposed) soy sauces. Although differences in flavor between traditional (honjozo) and modern (amino acid-decomposed) soy sauces are clear, knowledge of the differences in compound profiles and the relationship between these and the sensory characteristics that affect soy sauce quality is limited. Therefore, this study aimed to investigate the differences between traditional and modern soy sauce compounds using metabolomic analysis, and to investigate the compounds that may be correlated with differences in flavor. Non-targeted gas chromatography/mass spectrometry (GC/MS) metabolomics analysis was performed on nine traditional and six modern soy sauces to annotate 239 soy sauce compounds. Principal component analysis suggested that the production methods used formed clusters that affected the types and amounts of soy sauce compounds, and that the production method had a greater effect on soy sauce composition than did the aging barrels or type of soybean used. Traditional soy sauce was characterized by alcohols and esters, whereas modern soy sauce was characterized by pyrazines. A sensory evaluation revealed that traditional soy sauce was characterized by bitterness and astringency, whereas modern soy sauce was characterized by sweetness and viscosity, suggesting that the method of soy sauce production influences flavor differences. This is the first study to comprehensively characterize the effects of production methods, aging barrels, and soybean types on soy sauce compounds and how these compounds contribute to differences in flavor.

Although soy sauce is a globally used seasoning, its sensory properties have not been fully revealed. Here, the sensory characteristics of 149 soy sauces were examined using descriptive analyses. Eighty‐eight attributes were identified and integrated them into a flavor wheel. Aroma was the sensory modality described most often, suggesting that soy sauce's aroma is likely important in characterizing its sensory quality. Nineteen out of 88 attributes were found in all soy sauces implying their importance in representing a soy sauce‐like quality. These 19 attributes allowed the discrimination of manufacturing methods and the successful generation of a comparison map. Other attributes appeared infrequently, indicating that all soy sauces are unique and that these attributes can be utilized to describe subtle differences in their characters.Practical applicationSince soy sauce has become a globally used seasoning, it is meaningful to define its attributes for sensory evaluation. Establishing the sensory attributes of soy sauce allows us to describe each soy sauce objectively and share sensory perceptions among consumers, producers, and researchers. A flavor wheel would facilitate people's systematical understanding of the sensory characteristics of soy sauce. Also sensory evaluation using a flavor wheel would be helpful in finding previously unrecognized attractive or non‐attractive characteristics in soy sauces, which ultimately affects purchase decisions. Defining the minimum attributes required for creating a soy sauce positioning map would save a great deal of time and money for product development. Finally, knowledge about the relationship between sensory qualities and the manufacturing process and/or production area would be helpful in regards to product development and purchasing decisions.

Tempeh is an indigenous traditional fermented food from Indonesia that is rich in protein and phenolics. Unfortunately, tempeh is highly perishable, with a shelf life of 36-48 hours at room temperature. Making soy sauce from tempeh can increase tempeh’s functional value and shelf life. However, tempeh-based soy sauce has different sensory characteristics than koji-based soy sauce. Therefore, molasses can be used to increase consumer preferences. Molasses is a sweetener that has a unique aroma of caramels and dark color. This research aims to determine the effect of molasses addition on the physicochemical and sensory characteristics of tempeh soy sauce based on consumer preferences. Four different concentrations of molasses (0%, 2%, 4% and 6%) in tempeh soy sauce were used in this research, with commercial soy sauce as a benchmark. After soy sauce was fermented for 2 months, L*, a* and b* values, total dissolved solids (TDS), hedonic and just about right (JAR) tests were analyzed. Results showed that adding molasses significantly increased L*, a*, b* and TDS values. Commercial soy sauce and tempeh-based soy sauce with 4% molasses and 6% molasses additions were not significantly different and were the most preferred. Based on the penalty test, commercial soy sauce and the addition of 4% molasses do not have the characteristics of entering the critical corner.

Soy sauce contains a variety of volatiles that are highly valuable to its quality with regard to sensory characteristics. This paper describes the analysis of volatile compounds influencing the flavor quality of Chinese-type soy sauces. Gas chromatography-mass spectrometry (GC-MS) combined with headspace-solid phase microextraction and electronic nose (E-nose) were applied for identifying the volatile flavor compounds as well as determining their volatile profiles of 12 soy sauces manufactured by different fermentation process. Forty one key volatile components of these 12 soy sauce products, a pure soy sauce and an acid-hydrolyzed vegetable protein sample, were compared in semi-quantitative form, and their volatile flavor profiles were analyzed by E-nose. The substantially similar results between hierarchical cluster analysis based on GC-MS data and E-nose analysis suggested that both techniques may be useful in evaluating the flavor quality of soy sauces and differentiating soy sauce products. The study also showed that there were less volatile flavor compounds in soy sauces produced through low-salt solid-state fermentation process, a traditional manufacturing technology and a widely adopted technology in Chinese soy sauce industries. In addition, the investigation suggested that the flavor quality of soy sauce varied widely in Chinese domestic market, and that the present Chinese national standards of soy sauce should be further perfected by the addition of flavor grades of soy sauce in the physical and chemical index. Meanwhile, this research provided valuable information to manufacturers and government regulators, which have practical significance to improve quality of soy sauces.

Home-made soy sauces with or without Hovenia dulcis Thunb (Hutgae) originated from different parts such as fruits, stems, and twigs were prepared according to the Korean traditional procedure. Soy sauces supplemented with Hutgae were evaluated for their activities of 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) and alcohol dehydrogenase (ADH), free amino acid profiles, and sensory quality. All soy sauce types containing Hutgae had a strong DPPH activity as compared to the general type of soy sauce without Hutgae (GSC). Among Hutgae groups, DPPH activities of soy sauce supplemented with Hutgae stems was higher than that of soy sauces with either Hutgae fruits or twigs. ADH activities of soy sauces with Hutgae ranged from 14% to 55%, thus indicating that the functional activity of Hutgae was not altered during soy sauce preparations. Total free amino acid content of GSC was 295.5 ㎎%, and that of soy sauce with Hutgae fruits (346.8 ㎎%) was the highest when compared to Hutgae stems (272.3 ㎎%) and Hutgae twigs (225.6 ㎎%). In amino acid profiles, aspartate, arginine, histidine, and lysine levels were higher in soy sauces with Hutgae compared to GSC, whereas isoleucine, leucine, and phenylalanine levels were lower. Particularly, high levels of aspartate, glutamate, threonine, and lysine were presented in Hutgae twigs, whereas for Hutgae fruits and Hutgae stems, the levels of serine, glycine and arginine, and proline and methionine were high, respectively. According to sensory evaluations, Hutgae stems were preferred than GSC, due to the lower offensive smell and higher umami tastes. These findings demonstrate that soy sauce with Hutgae stems has potential protective effects against hangovers, improves the taste, and implies a possible functional ingredient.Key words: Hutgae fruit, soy sauce, DPPH, alcohol dehydrogenase (ADH), sensory evaluation

The present study aimed to determine the components related to sensory properties in soy sauce and to characterize the differences between low-salt solid-state fermented soy sauce (LSFSS) and high-salt diluted-state fermented soy sauce (HDFSS). The taste and aroma active components of 18 commercially available soy sauces (eight types of LSFSS and 10 types of HDFSS) were characterized. The relationship between these compounds, soy sauce samples, and sensory properties was modeled by partial least squares regression. The analysis showed that the 11 taste-active components, including glutamic acid, glycine, alanine, threonine, malic acid, citric acid, tartaric acid, acetic acid, lactic acid, reducing sugar and salt, contributed greatly to the taste of soy sauce. In addition, umami, saltiness and sweetness are the characteristic tastes of HDFSS, whereas sourness and bitterness were the characteristic tastes of LSFSS. At the same time, seven aroma-active compounds, namely 4-ethyl-2-methoxyphenol, ethanol, 3-methyl-1-butanol, ethyl acetate, 2-phenethyl alcohol, 3-methyl thiopropanol and 2-ethyl-4-hydroxy-5-methylfuran-3-one, played a decisive role in the flavor of soy sauce. In addition, HDFSS presented the aroma attributes of smoky, alcoholic, floral, fruity and caramel-like, whereas LSFSS mainly presented sour and malty aroma attributes. The present study reveals new insight into the relationship between the chemical composition and sensory characteristics of soy sauce, which is of great significance for developing an objective measurement system and providing a theoretical basis to improve the sensory quality of soy sauce. © 2023 Society of Chemical Industry.

Effect of salt concentration on Chinese soy sauce fermentation and characteristics

Macroporous resin purification of peptides with umami taste from soy sauce

Application of compressed sensing for selecting relevant variables for a model to predict the quality of Japanese fermented soy sauce

As interest continues in sodium reduction technologies, there is a need to understand the changes in physiochemical and sensory characteristics of reduced sodium food products. Previous research has shown that traditionally brewed soy sauce (SS) and fermented flavor enhancer (NFE) offer efficacy as viable sodium reduction ingredients. However, their ability to provide similar results in other meat products with different requirements (e.g., flavor, functionality, etc.) for salt is not well understood. In this study, bacon, beef jerky, summer sausage, and boneless ham treatments were generated with sodium reductions of 30 and 50% by including either SS or NFE alone and in combination with potassium chloride (KCl). Sensory and quality measurements, including salty taste, and product qualities such as color, purge, and texture profiles were evaluated. No differences (P > 0.05) were observed for overall liking of bacon at 30 (SS and NFE) and 50% (SS) reductions containing KCl, and for overall liking of beef jerky (NFE) and boneless ham (SS) at 30% reductions utilizing either SS or NFE as a salt reduction tool. Further, saltiness liking scores showed no change (P > 0.05) at 30% reductions in bacon, beef jerky and boneless ham, while a decreased liking (P < 0.05) were observed in summer sausage products containing SS and NFE. These results suggest the use of SS and NFE can increase perceived salty taste without increasing the sodium content of multiple products investigated. These results indicated that SS and NFE are suitable ingredients to utilize in processed meat products to reduce sodium content, while each product has unique and variable responses in sensory attributes that must be considered.

Soy sauces are available in different types and grades, which allows them to reach consumers of all socioeconomic groups. Ferric sodium ethylenediaminetetraacetic acid (NaFeEDTA) has been used for iron fortification of soy sauces in some countries, however, its high cost may make it unattractive to policymakers and industry. We evaluated the feasibility of using more economical iron sources for iron fortification, with soy sauce of various types and grades used as a vehicle. Seven iron sources were tested for their feasibility for fortification of four types of soy sauce: naturally fermented in the traditional style, naturally fermented according to large-scale industrial formulas 1 and 5, and chemically hydrolyzed at 5 mg per serving (15 mL, per Thailand's food labeling regulations). Either citric acid or sodium citrate was added at 0.1% as a chelator. Five iron sources--ferrous sulfate, NaFeEDTA, ferric ammonium citrate, ferrous lactate, and ferrous gluconate--did not significantly affect the sensory qualities of the product over a period of 3 months (p > .05). Ferrous fumarate and ferrous bisglycinate caused unacceptable precipitation. Less than 3% of 260 and 306 commonly cooked foods out of 871 and 772 preparations using soy sauces fortified with NaFeEDTA and ferrous sulfate, respectively, were found to be different from normal with regard to sensory qualities. The cost of fortification was US 0.22 cents to US 3.28 cents per bottle (700 mL). Both naturally fermented and chemically hydrolyzed soy sauces could be fortified with all five iron sources. Ferrous sulfate is the most appropriate source because of its low cost and acceptable sensory characteristics. Soy sauce is a promising vehicle for iron fortification, however, the bioavailability of iron in the products examined here needs to be evaluated under normal use conditions.

Soy sauce is a traditional salty liquid condiment produced by fermenting soybeans. However, the increasingly high price of soybeans on the market has led to the need for alternative substitutes to the raw material for making soy sauce. Sorghum (Sorghum bicolor (L.) Moench.) is a cereal crop that is widely grown in Indonesia and has high carbohydrate and protein content but has yet to be utilized optimally, so sorghum has the potential to be used as a functional. The sensory quality of soy sauce is affected by the fermentation process. This research aims to analyze the effect of adding yeast variations and fermentation time on the physicochemical and sensory quality characteristics of sorghum soy sauce. The research method used a wholly randomized factorial design with three repetitions. The first factor is yeast variations, which use two levels, Rhizopus oligosporus and Saccharomyces cerevisiae. The second factor is the fermentation time, with four levels, namely 7, 11, 15, and 19 days. The resulting soy sauce is then analyzed for protein content, acidity, viscosity, and sensory analysis using the attributes of taste, color, and flavor. The data obtained was processed with SPSS software using two-way ANOVA and Least Significant Difference (LSD) if the results obtained had a significant effect. The research results showed that the use of various types of yeast has a substantial impact on the protein content, viscosity, and flavor attributes of sorghum soy sauce. Meanwhile, fermentation time treatment had a significant effect on acidity and color. Overall, the best treatment was obtained by adding Saccharomyces cerevisiae with a fermentation time of 11 days, resulting in a protein content of 1.32%, acidity of 4.60, and viscosity of 3.11 cp. Sensory analysis showed that the best treatment was soy sauce fermentation using Rhizopus oligosporus for 11 days, which obtained a taste attribute value of 3.24, flavor value of 2.21, and color value of 3.96.

To solve the serious problem of homogenising commercial soy sauce, peanut meal, a high-quality plant protein resource, was used to replace soybean meal to ferment soy sauce. In this study, we investigated the effects of different raw material ratios (w/w) and starters on the physicochemical and antioxidant activities, sensory characteristics and flavour of soy sauce. The results showed that peanut meal helped to increase the protease activity of koji, deepen the colour of soy sauce, improve the antioxidant activity of soy sauce, and enrich the aroma of soy sauce. The total phenol and total flavonoid content of PMSS (2:2) with starters were increased by 20% and 36%, respectively, compared to soybean meal soy sauce. The results of SPME-GC–MS and recombination and omission experiments showed that the aroma of peanut meal soy sauce was more complex and more abundant in esters, pyrazines, and phenols. Ethyl 2-methylbutanoate, Apricolin, 2-Methyl-1-butanol, and Isovaleraldehyde in peanut meal had high OAV values. In addition, PMSS (2:2) with starters had the highest sensory score, with intense fruity, caramel, malty, and smoky aromas. These results show that peanut meal can improve the quality and flavour of soy sauce and provide a theoretical basis for the development of peanut soy sauce.

Korean traditional soy sauce was fermented for 120 days in ceramics obtained from five different regions in Korea. The average internal and external temperatures of soy sauce in ceramics were 20.0 and 18.3 °C, respectively. Physicochemical, microbiological, and sensory characteristics were analyzed. Ceramics from different regions generated differences in physicochemical characteristics. Soy sauce fermented in the southwest regional ceramic, which has a low height and wide circumference, had significantly lower salt content, higher reducing sugar content, and protease activity rather than others. In descriptive analysis, soy sauce fermented in the ceramic from Seoul capital region had a lower intensity of saltiness and biting taste, whereas the soy sauce in the southwest ceramic had comparable saltiness and biting taste attributes as those in the southeast and central regions, and Jeju Island ceramics. Five regional ceramics were categorized into three groups by principal component analysis. Based on the physicochemical characteristics, soy sauces from southwest and Seoul capital regions had distinctive characteristics in comparison with the soy sauces from Jeju Island, southeast, and central regions.

The objective of this study was to investigate the sensory quality attributes for the development of soy sauce containing an extract of the fruit of Hovenia dulcis Thunb (Hutgae), also known as liver function improvement and hangover removal. Aqueous extracts of Hutgae fruit and Hutgae fruit-soy sauce were used for determining the sensory evaluation. The intensity of the sweet smell and taste was predominated in the Hutgae fruit extract (p<0.05). Various seasoning items, such as apples, pears, dried figs, Korean bramble (Bokbunja), citron (Yuza) and sun-dried hot pepper (Taeyangcho), were used to determine the suitable type of seasoned soy sauce with the Hutgae fruit extract. In the sensory analysis, the highest overall preference (acceptance score 5) was obtained from the pear extract added to soy sauce with the Hutgae fruit. The overall preference of Yuza (score 4.9) and Taeyangcho (score 4.5) extracts also very well-matched the seasoning items for soy sauce with the Hutgae fruit extract. There was no difference among the extract mixtures of multi-seasoning items added to soy sauce with the Hutgae fruit extract. As more pear extract was added, a higher overall preference was obtained. On the other hand, as the more Yuza extract was added, the higher flavor intensity without the change of the overall preference was obtained. The overall preference of soy sauce with the pear- Yuza-Taeyangcho extract mixture was not different between with or without the Hutgae fruit extract. However, the overall preference (score 5.6) was significantly higher in the pear extract added to soy sauce with the Hutgae fruit extract compared with the pear extract added to soy sauce without the Hutgae fruit extract (score 4.8). These results suggest that soy sauce with the Hutgae fruit-pear extract mixture may be useful as a functional seasoning for various salad dressings.