Improvement of fish sauce quality by combined inoculation of Tetragenococcus halophilus MS33 and Virgibacillus sp. SK37

Abstract

Biological and chemical dynamics were investigated during fermentation of fish sauce inoculated single and combined starter cultures, Virgibacillus sp. SK37 and Tetragenococcus halophilus MS33. At 120–150 days of fermentation, cell numbers of Virgibacillus sp. SK37 and T. halophilus MS33 were lower as detected by qPCR in fish sauce inoculated with a single culture compared with the sample inoculated with combined cultures. In addition, qPCR revealed that the sequential inoculation of Virgibacillus sp. SK37 followed by the addition of T. halophilus MS33 after 1 month (SK37_1M + MS33) showed bacterial counts that were approximately 0.5–1 LogCFU/mL higher than the single starter culture treatments. α-Amino contents of fish sauce added simultaneous co-cultures (MS33 + SK37) and SK37_1M + MS33 were 1160.41 and 1185.71 mM, respectively. SK37_1M + MS33 showed a lower amount of histamine than the control (P < 0.05). Fish sauce samples inoculated with either sequential cultures or a single culture of Virgibacillus sp. SK37 or T. halophilus MS33 showed higher amounts of total glutamic acid and greater total amounts of amino acids than the control (P < 0.05). The amounts of key desirable volatiles, namely 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal, were higher in SK37_1M + MS33 than in the control (without starter culture, P < 0.05). The addition of both starter cultures in sequential order showed the potential to improve quality in terms of volatile compounds, glutamic acid content and overall acceptability.