Studies on the Key Aroma Compounds in Raw (Unheated) and Heated Japanese Soy Sauce

Abstract

An investigation using the aroma extract dilution analysis (AEDA) technique of the aroma concentrate from a raw Japanese soy sauce and the heated soy sauce revealed 40 key aroma compounds including 7 newly identified compounds. Among them, 5(or 2)-ethyl-4-hydroxy-2(or 5)-methyl-3(2H)-furanone and 3-hydroxy-4,5-dimethyl-2(5H)-furanone exhibited the highest flavor dilution (FD) factor of 2048, followed by 3-(methylthio)propanal, 4-ethyl-2-methoxyphenol, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone having FD factors from 128 to 512 in the raw soy sauce. Furthermore, comparative AEDAs, a quantitative analysis, and a sensory analysis demonstrated that whereas most of the key aroma compounds in the raw soy sauce were common in the heated soy sauce, some of the Strecker aldehydes and 4-vinylphenols contributed less to the raw soy sauce aroma. The model decarboxylation reactions of the phenolic acids during heating of the raw soy sauce revealed that although all reactions resulted in low yields, the hydroxycinnamic acid derivatives were much more reactive than the hydroxybenzoic acid derivatives due to the stable reaction intermediates. Besides the quantitative analyses of the soy sauces, the estimation of the reaction yields of the phenolic compounds in the heated soy sauce revealed that although only the 4-vinylphenols increased during heating of the raw soy sauce, they might not mainly be formed as decarboxylation products from the corresponding hydroxycinnamic acids but from the other proposed precursors, such as lignin, shakuchirin, and esters with arabinoxylan.

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

“…Benzeneacetic acid ethyl ester, a high boiling point ester, did not present in aHVP sample. This compound, being one of the major contributors to soy sauce flavor (Kaneko et al 2012(Kaneko et al , 2013, was found at low concentration in pure soy sauce sample and several soy sauce products. It is noteworthy that the amount of fatty acid ester in soy sauce depends on varieties of soybean which were used in the brewing material.…”

“…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.…”

“…The amount of phenylethyl alcohol in pure soy sauce sample, sample 11 and sample 12 was similar. 1-Octen-3-ol, which is also known as mushroom alcohol, is a contributor to the flavor of Japanese-type soy sauce (Kaneko et al 2012(Kaneko et al , 2013. The concentration of this compound in pure soy sauce sample was very low.…”

“…Aliphatic aldehyde, 3-(methylthio)-propanal, which contain sulfur and possess a strong onion and roast meat-like flavor, was also identified in pure soy sauce, aHVP, and three soy sauce products. It was the key aroma compound and major contributor of fragrance in soy sauces (Kaneko et al 2012(Kaneko et al , 2013. Like benzeneacetaldehyde, 3-(methylthio)-propanal was also found to be positively related to 'musty' and 'soy saucelike' odors and exhibited the greatest aroma intensities (Feng et al 2013a(Feng et al , b, 2015.…”

“…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.…”