Shoyu (soy sauce) flavor components: Neutral fraction.

Abstract

Fromthe vacuumdistilled volatiles ofshoyu, a neutral fraction was obtained. Shoyu was also directly extracted with dichloromethane and then the extract was separated into ten (A~J) fractions. The J fraction was a neutral one. The J fraction was further separated into twelve fractions by liquid column chromatography. All fractions obtained were analyzed by gas chromatography and combined gas chromatography-mass spectrometry. Consequently, 142 components were identified, 82 of which have not been reported previously as volatile constituents of shoyu. The identified compounds were 37 hydrocarbons, 22 alcohols, 22 carbonyls, 22 esters, 12furans, 6 sulfurous compounds, 1 pyrone, 5 phenols, 1 furanone, 1 acid, 1 lactone and 12 other compounds.Fromthe results of quantitative analysis and organoleptic evaluation, phenylacetaldehyde is considered to be most important in the neutral fraction.In the previous papers,1~5) the authors reported that 131 flavor components were identified in shoyu and that 4-hydroxy~2(or 5)-ethyl-5(or 2)-methyl-3(2i/)-furanone (abbreviated as HEMF,tautomers ratio: ca. 3 : 2) was the main and the most important constituent of the characteristic flavor of shoyu. In these Studies, the basic, acidic I, acidic II and neutral fractions were obtained from the vacuumdistilled volatiles ofshoyu, and the volatiles in the basic3) and acidic5} fractions have been investigated. It was also reported that the direct extract of shoyu with dichloromethane was separated into ten (A-J) fractions5) in order to cover the components that were not obtained by the above method. This work was concerned with the identification of many components in the uninvestigated fractions of shoyu; i.e. the volatile neutral fraction and the neutral J fraction from the direct extract with dichloromethane. Some components contributing to the odor of the neutral fraction were also discussed. MATERIALS AND METHODSShoyu. Commercially available Japanese genuine fermented shoyu (pH 4.8) was used for the following experiments.Separation of a volatile shoyu flavor concentrate into acidic, basic and neutral fractions. Four fractions (basic, acidic I, acidic II and neutral) were obtained from the vacuumdistilled volatiles by the method described in the previous paper.5) All concentrations and pH adjustments were carried out at a temperature of below 50°C.Separation of a shoyu flavor concentrate (CH2Cl2 extract) into ten fractions. The direct dichloromethane extract, 19.5g, was obtained from 40 liters of shoyu. The extract was fractionated into ten (A~J) fractions by the method described in the previous papers.4'5] The A and B fractions were basic; the C~I fractions were acidic and the J fraction was neutral. All concentrations and pH adjustments were carried out at a temperature of below 50°C. The weight ratio of each fraction to total extract was calculated; the basic ones were 27%, the acidic ones were 57%and the neutral one was 16%.

Analysis of volatile flavor compounds influencing Chinese-type soy sauces using GC–MS combined with HS-SPME and discrimination with electronic nose

“…Nevertheless, the typical compound of soy sauce, 4-EG, and 4-EP, were not found in aHVP sample. 2-methoxy-phenol, typically described as smoky, spicy, and medicine-like (Nunomura et al 1984;Kaneko et al 2012Kaneko et al , 2013, was detected in all samples, while phenol was not found in pure soy sauce sample. By calculation, it was clear that the total amount of phenols in pure soy sauce sample was not high and phenols accounted for a little part of volatile flavor compounds.…”

“…Among these compounds, dozens of components were shared commonly with different amount in soy sauce products. According to the previous report (Nunomura et al 1984;Kaneko et al 2012Kaneko et al , 2013Feng et al 2015), some typical or key volatile flavor compounds, which might be the contributors to the flavor of soy sauce, were summarized in Table 2.…”

“…It was also identified in most soy sauce products with the exception of aHVP sample, sample 6 and sample 11. 4-EG, which was formed from lignin degradation by asperillus during fermentation (Bao 2011;Nunomura et al 1984;Gao et al 2010), was an important contributor to soy sauce aroma with 1 ppm could be sensory (Bao 2011). In contrast to other phenols, the amount of 4-EG in soy sauce was not significantly higher.…”

“…Volatile chemical compounds make a critical contribution to the typical flavor of soy sauce. Volatile organic compounds in various soy sauces, including Japanese-type soy sauces (Nunomura et al 1984;Kaneko et al 2012Kaneko et al , 2013Meng et al 2012;Hayase et al 2013;Aishima 2006;Feng et al 2013a, b), Thai-type soy sauce (Wanakhachornkrai and Lertsiri 2003;Lertsiri et al 2010), Korea-type soy sauces (Baek and Kim 2004;Lee et al 2006) and Chinese-type soy sauces (Zhang and Tao 2009;Gao et al 2010;Sun et al 2010;Feng et al 2015), have been investigated and some of the volatiles such as alcohols, esters, phenols, acids, and heterocyclics have been identified.…”

Profile of Volatile Compounds in 12 Chinese Soy Sauces Produced by a High-Salt-Diluted State Fermentation

“…The main steps in flavour development in soy sauce production are heat treatment of raw materials, koji culturing and the mash fermentation 31 . There have been a few studies conducted to determine the volatile compounds in soy sauces produced in different Asian countries or regions 1,16,19,21,26,31 . For example, Nunomura and co-authors [19][20][21] investigated the volatile compounds of Japanese soy sauce using a combination of vacuum distillation-solvent distillation and gas chromatography-mass spectrometry.…”