Vital parameters for high gamma-aminobutyric acid (GABA) production by an industrial soy sauce koji Aspergillus oryzae NSK in submerged-liquid fermentation

Wan Abd Al Qadr Imad Wan-Mohtar; Safuan Ab Kadir; Sarina Abdul Halim-Lim; Zul Ilham; Siti Hajar-Azhari; Nazamid Saari

doi:10.1007/s10068-019-00602-y

Vital parameters for high gamma-aminobutyric acid (GABA) production by an industrial soy sauce koji Aspergillus oryzae NSK in submerged-liquid fermentation

Food Sci Biotechnol. 2019 Mar 22;28(6):1747-1757. doi: 10.1007/s10068-019-00602-y. eCollection 2019 Dec.

Authors

Wan Abd Al Qadr Imad Wan-Mohtar¹, Safuan Ab Kadir², Sarina Abdul Halim-Lim³, Zul Ilham⁴, Siti Hajar-Azhari², Nazamid Saari²

Affiliations

¹ 1Functional Omics and Bioprocess Development Laboratory, Biotechnology Program, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
² 2Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Malaysia.
³ 4Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Malaysia.
⁴ 3Biomass Energy Laboratory, Environmental Science and Management Program, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.

Abstract

In submerged-liquid fermentation, seven key parameters were assessed using one-factor-at-a-time to obtain the highest GABA yield using an industrial soy sauce koji Aspergillus oryzae strain NSK (AOSNSK). AOSNSK generated maximum GABA at 30 °C (194 mg/L) and initial pH 5 (231 mg/L), thus was able to utilize sucrose (327 mg/L of GABA) for carbon source. Sucrose at 100 g/L, improved GABA production at 646 mg/L. Single nitrogen sources failed to improve GABA production, however a combination of yeast extract (YE) and glutamic acid (GA) improved GABA at 646.78 mg/L. Carbon-to-nitrogen ratio (C8:N3) produced the highest cell (24.01 g/L) and GABA at a minimal time of 216 h. The key parameters of 30 °C, initial pH 5, 100 g/L of sucrose, combination YE and GA, and C8:N3 generated the highest GABA (3278.31 mg/L) in a koji fermentation. AOSNSK promisingly showed for the development of a new GABA-rich soy sauce.

Keywords: Aspergillus oryzae; GABA-enriched foods; Gamma-aminobutyric acid (GABA); Glutamic acid; Soy sauce koji.