Biochemical changes in low-salt solid-state fermented soy sauce

Abstract

Low-salt solid-state fermentation soy sauce was prepared with defatted soy bean and wheat bran. Biochemical changes during the aging of the soy sauce mash were investigated. Results showed that after a 15-day aging period, the contents of total nitrogen, formol titration nitrogen, free amino acids, reducing sugar, total sugar and the brown color were increased. However, pH was decreased during the fermentation period. Furthermore, contents of total free amino acids in low-salt solid-state fermentation soy sauce fluctuated during the fermentation period, and in most periods, it was increased. The analysis of free amino acid composition shows that the contents of glutamic acid, aspartic acid, alanine and leucine were higher than other amino acids. Therefore, it means that these amino acids may contribute to the taste and flavor of low-salt solid-state fermentation soy sauce. The biochemical changes characters were due to enzyme activities, solution balance and reaction balance, and biochemical changes contributed to the improvement of the flavor of low-salt solid-state fermented soy sauce. Analyzing the biochemical change in the fermented process of soy sauce is helpful in finding out the shortcoming of low-salt solid-state fermented soy sauce.

Evaluation of non-volatile taste components in commercial soy sauces

“…Oxalic acid, tartaric acid, lactic acid, acetic acid, citric acid, succinic acid, hydrochloric acid (HCl), potassium ferrocyanide (K 4 [Fe(CN) 6 ]), zinc sulphate (ZnSO 4 ), potassium dihydrogen phosphate (KH 2 PO 4 ), phosphoric acid (H 3 PO 4 ), disodium hydrogen phosphate dodecahydrate (Na 2 HPO 4 •12H 2 O) (all AR grade), and malic acid (BR grade) were purchased from Sinopharm Chemical Reagent Co. (Shanghai, China). Pyroglutamic acid and pyruvic acid were purchased from Macklin Reagent Company (Shanghai, China).…”

“…[8,9] Zhang et al analysed taste compounds in Chinese solid fermented soy sauce and found that free amino acids, such as Glu, Asp, Arg, Leu, and Ala, were abundant and are recognised as important contributors to taste of the soy sauce. [4] Lioe et al compared three typical forms of Japanese soy sauce (shoyu), koikuchi, tamari, and shiro shoyu, and concluded all of them contain sodium salt, free Glu, and several other free amino acids, especially sweet taste-eliciting amino acids. [10] The taste of soy sauce is probably a result of the interaction and balance among different taste components.…”

“…[2] Soy sauce not only contributes to flavour but also enhances the taste of other ingredients to which it is added, especially the umami taste. [3,4] The flavor of soy sauce is generated from grain fermentation. [5] Brewed soy sauce is traditionally made from soybeans and may be fortified with wheat grains over several months after seeding with Aspergillus.…”

Recent progress and advances in soy sauce production technologies: A review

“…Although HLFSS is still produced, most commercial soy sauce manufacturers in China have adopted the LSFSS technique using pure starter cultures due to its shorter production cycle and lower cost. Nonetheless, HLFSS has a richer aromatic profile and complex composition of volatile compounds (Diez-Simon et al, 2020;Feng et al, 2015;Zhang, 2010). Soy sauce chemical composition differs according to the raw materials employed.…”

The effect of the Corynebacterium glutamicum on the shortening of fermentation time, physicochemical and sensory properties of soy sauce

“…High‐salt liquid‐state fermentation soy sauce (HLFSS) and low‐salt solid‐state fermentation soy sauce (LSFSS) typically have a brine concentration of 20% and 15%, and ageing period of approximately 90–180 days and 15–30 days, respectively (Zhang, 2015). Approximately 300 aroma compounds have been reported in soy sauce, with alcohols, esters and alkanes, and heterocyclic compounds mainly found at the initial stage, middle stage and final stage of fermentation, respectively (Wei et al ., 2013a).…”