Research advances on biogenic amines in traditional fermented foods: Emphasis on formation mechanism, detection and control methods

Halophilic bacteria as starter cultures: A new strategy to accelerate fermentation and enhance flavor of shrimp paste.

The objective of this study was to investigate the effects of halophilic bacteria, including Virgibacillus sp. ZV10-1, Virgibacillus sp. SK37, and Staphylococcus nepalensis JS11 as starters on physicochemical, sensory, and taste properties of rapidly-fermented shrimp paste. Halophilic bacteria reduced moisture and total volatile basic nitrogen content and increased the pH and amino acid nitrogen content of shrimp pastes. Higher levels of total organic acids (484.47 ± 10.40 mg/100 g) were detected in sample inoculated with S. nepalensis JS11. Assessment of sensory parameters indicated that the three-bacteria compound inoculation group improved taste of shrimp paste effectively and contained the highest level of free amino acids (8930.25 ± 3.51 mg/100 g) and equivalent umami concentration (EUC) (960.32 g MSG/100 g). Furthermore, partial least squares regression analysis demonstrated that rapidly-fermented shrimp pastes were associated with sweetness, umami, color, texture, and overall liking attributes, which were related to the presence of tartaric acid, malic acid, GMP, Glu, Asp, Arg and Thr. Thus, this study highlights the potential of Virgibacillus sp. SK37 and S. nepalensis JS11 for the production of rapidly-fermented shrimp paste with improved taste profiles.

Virgibacillus sp. SK37 and Staphylococcus nepalensis JS11 as potential starters to improve taste of shrimp paste

Microbial diversity is essential for determining the characteristic quality of fermented sea bass products. However, how microbial community succession affects metabolite profiles during fermentation remains poorly understood. In this study, using 16S and 18S rRNA gene sequencing, eight bacterial and four fungal microorganisms were identified as the dominant genera during the fermentation of sea bass. Ultra-high performance liquid chromatography with triple time-of-flight mass spectrometry was used to identify the metabolite profiles and a total of 54 metabolites were identified. Our results showed that the metabolic activities of Streptococcus, Macrococcus, Psychrobacter, Trichosporon, and Aspergillus were correlated with the production of amino acids, peptides, amines, lipids, and organic acids. Metabolic pathway analysis showed that these metabolites are related to various types of amino acid metabolism. We hope that our study will provide a new theoretical basis and research perspective that may improve the sea bass fermentation process. 

Exploring the roles of microorganisms and metabolites in the fermentation of sea bass (Lateolabrax japonicas) based on high-throughput sequencing and untargeted metabolomics

Correlation between dominant bacterial community and non-volatile organic compounds during the fermentation of shrimp sauces

Huanghua shrimp paste is well-known as a traditional salt-fermented food in China. So far, however, little is known about its quality characteristics and bacterial community. The quality of Huanghua salt-fermented shrimp paste was evaluated in this work by determining the pH values, amino acid nitrogen (AAN), malondialdehyde (MDA), nitrite and biogenic amines (BAs). Moreover, the bacterial community of shrimp paste was analyzed by using the high-throughput sequencing technology. The results showed that the pH, AAN, MDA, nitrite and total BA content in shrimp paste were in ranges of 6.77–8.25, 0.16–0.35 g/100 g, 0.25–1.10 mg/kg, 0.18–0.49 mg/kg and 18.20–469.02 mg/kg, respectively. The main BAs were tryptamine, histamine and tyramine. Bacterial community analysis indicated that Firmicutes and Proteobacteria were the most dominant phylum in all shrimp paste samples. Enterococcaceae, Pseudomonadaceae and Staphylococcaceae were the most predominant family. The major bacteria genera in shrimp paste were Tetragenococcus, Lactobacillus and Halanaerobium. The correlation between AAN, histamine and tyramine contents and Tetragenococcus were 0.71, 0.62 and 0.67 (R2 values), respectively. These findings expand the understanding for Huanghua salt-fermented shrimp paste and provide a theoretical basis for improving the fermentation process of shrimp paste.

Zehe He

Papers

Quality characteristics and bacterial community of a Chinese salt-fermented shrimp paste