The production of functional γ-aminobutyric acid Malaysian soy sauce koji and moromi using the trio of Aspergillus oryzae NSK, Bacillus cereus KBC, and the newly identified Tetragenococcus halophilus KBC in liquid-state fermentation

• Main Authors: Shin Yee, C., Sohedein, M.N.A., Poh Suan, O., Weng Loen, A.W., Abd Rahim, M.H., Soumaya, S., Ilham, Z., Wan-Mohtar, W.A.A.Q.I.
• Format: Article
• Published: Elsevier B.V. 2021
• Subjects: S Agriculture (General)
• Online Access: http://eprints.um.edu.my/35928/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85111754006&doi=10.1016%2fj.fufo.2021.100055&partnerID=40&md5=0d839b951bae98055ef7b846000ad275
• Institution: Universiti Malaya

Soy sauce fermentation was improved using the trio of A. oryzae (AO), B. cereus (BC), and the newly identified Tetragenococcus halophilus KBC (TH) in liquid-state fermentation. The effect of molasses (5, 10, and 20) and type of wheat flour (organic-WFO and commercial-WFC) were tested on the koji-moromi formulation for efficient ɣ-aminobutyric acid (GABA) production. The koji-WFO produced higher GABA (1290 mg/L) compared to koji-WFC (13 mg/L). In the initial moromi mixture, 2 × 10−4 mL of BC inoculum containing 5–20 of molasses was added and replaced the same amount with TH in the second trial. Subsequently, the moromi was mixed with 1 × 10−4 mL of BC and TH, which shortened the 60-day moromi process to 30 days. Meanwhile, BC-moromi cultured in 20 molasses generated significantly lower GABA (118 mg/L) production compared to other percentages, however the concentration boosted for TH-moromi in 20 molasses (159 mg/L). The combination of BC-TH percentages (5–20) gave significantly lower GABA (83–137 mg/L) than the singular 20 TH treatment. The results promote the use of TH in producing high-GABA soy sauce. © 2021