The role of microorganisms in soy sauce production

Research on microbial diversity and nutritional flavor formation of Xianju wheat paste

BACKGROUND

Xianju wheat paste, a traditional condiment in Hubei Province, China, possesses nutritional value and a distinctive taste profile. Nevertheless, there remains a dearth of comprehensive comprehension regarding the intricate interplay between the microbial population and its nutritional profile in Xianju wheat paste.

RESULTS

It was determined that Xianju wheat paste harbors predominant microbial genera such as Bacillus, Staphylococcus and Aspergillus. The findings from high-throughput sequencing analysis revealed the presence of 11 bacterial genera in Xianju wheat paste, with relative abundances exceeding 1%. These genera included Bacillus, Staphylococcus, Brevibacterium, Lactobacillus, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Enterobacteriaceae, Pantoea, Brachybacterium, Klebsiella, Escherichia-Shigella and Ochrobactrum. Furthermore, six fungal genera were identified with relative abundances greater than 1%, specifically Aspergillus, Zygosaccharomyces, Cutaneotrichosporon, Candida, Millerozyma and Rhizopus. The correlation analysis indicated a significant impact of the microbial community and nutritional flavor on the second phase of fermentation in Xianju wheat paste. The predominant bacterium Bacillus in Xianju wheat paste facilitated the production of free amino acids, whereas Staphylococcus exhibited a negative correlation with free amino acid levels. The quantity of volatile compounds in Xianju wheat paste progressively increased during fermentation, with the presence of typical aroma compounds 4-vinyl-2-methoxyphenol significantly associated with Bacillus. This indicated Bacillus notably enhanced the production of aromatic substances. Furthermore, a strong correlation was observed between Staphylococcus and the 18 volatile organic compounds, highlighting their substantial contribution to these aroma compounds.

CONCLUSION

This research indicates that the presence of microbial communities significantly contributes to the development of the nutritional flavor profile in Xianju wheat paste. © 2024 Society of Chemical Industry.

Polysaccharide intercellular adhesin and proper phospholipid composition are important for aggregation in Tetragenococcus halophilus SL10

Aggregating strains of Tetragenococcus halophilus tend to be trapped during soy sauce mash-pressing process and are, therefore, critical for clear soy sauce production. However, the precise molecular mechanism involved in T. halophilus aggregation remains elusive. In previous studies, we isolated a number of aggregating strains, including T. halophilus AB4 and AL1, and showed that a cell surface proteinaceous aggregation factor is responsible for their aggregation phenotype. In the present study, we explored the role of polysaccharide intercellular adhesin (PIA) in aggregate formation in T. halophilus SL10, isolated from soy sauce. SL10 exhibited similar aggregation to AB4 and AL1 but formed a non-uniform precipitate with distinctive wrinkles at the bottom of the test tube, unlike AB4 and AL1. Insertion sequence mutations in each gene of the ica operon diminished aggregation and PIA production, highlighting the critical role of IcaADBC-mediated PIA production in T. halophilus aggregation. Furthermore, two non-aggregating cardiolipin synthase (cls) gene mutants with intact ica operon did not produce detectable PIA. Phospholipid composition analysis in cls mutants revealed a decrease in cardiolipin and an increase in phosphatidylglycerol levels, highlighting the association between phospholipid composition and PIA production. These findings provide evidence for the pivotal role of cls in PIA-mediated aggregation and lay the foundation for future studies to understand the intricate networks of the multiple aggregation factors governing microbial aggregation.IMPORTANCEAggregation, commonly observed in various microbes, triggers biofilm formation in pathogenic variants and plays a beneficial role in efficient food production in those used for food production. Here, we showed that Tetragenococcus halophilus, a microorganism used in soy sauce fermentation, forms aggregates in a polysaccharide intercellular adhesin (PIA)-mediated manner. Additionally, we unveiled the relationship between phospholipid composition and PIA production. This study provides evidence for the presence of aggregation factors in T. halophilus other than the proteinaceous aggregation factor and suggests that further understanding of the coordinated action of these factors may improve clarified soy sauce production.

An overview of fermentation in the food industry - looking back from a new perspective

Fermentation is thought to be born in the Fertile Crescent, and since then, almost every culture has integrated fermented foods into their dietary habits. Originally used to preserve foods, fermentation is now applied to improve their physicochemical, sensory, nutritional, and safety attributes. Fermented dairy, alcoholic beverages like wine and beer, fermented vegetables, fruits, and meats are all highly valuable due to their increased storage stability, reduced risk of food poisoning, and enhanced flavor. Over the years, scientific research has associated the consumption of fermented products with improved health status. The fermentation process helps to break down compounds into more easily digestible forms. It also helps to reduce the amount of toxins and pathogens in food. Additionally, fermented foods contain probiotics, which are beneficial bacteria that help the body to digest food and absorb nutrients. In today's world, non-communicable diseases such as cardiovascular disease, type 2 diabetes, cancer, and allergies have increased. In this regard, scientific investigations have demonstrated that shifting to a diet that contains fermented foods can reduce the risk of non-communicable diseases. Moreover, in the last decade, there has been a growing interest in fermentation technology to valorize food waste into valuable by-products. Fermentation of various food wastes has resulted in the successful production of valuable by-products, including enzymes, pigments, and biofuels.

Enhancing Protease and Amylase Activities in Bacillus licheniformis XS-4 for Traditional Soy Sauce Fermentation Using ARTP Mutagenesis

This study was conducted to increase the enzymatic activity of Bacillus licheniformis XS-4, which was isolated from the traditional fermented mash of Xianshi soy sauce. The mutation was induced by atmospheric and room-temperature plasma (ARTP), and a mutant strain, mut80, was obtained. mut80 exhibited significant increases in protease and amylase activity by 90.54% and 143.10%, respectively, and the enhanced enzymatic activities were stably maintained after 20 consecutive incubations. Re-sequencing analysis of mut80 revealed that the mutation sites were located in 1518447(AT-T) and 4253106(G-A) in its genome, which was involved in the metabolic pathways of amino acids. The expression of the protease synthetic gene (aprX) increased 1.54 times, while that of the amylase gene (amyA) increased 11.26 times, as confirmed via RT-qPCR. Using ARTP mutagenesis, the present study proposes a highly efficient microbial resource with enhanced protease and amylase activity provided by B. licheniformis, which can potentially be used to improve the efficiency of traditional soy sauce fermentation.

By-Products of the Black Soybean Sauce Manufacturing Process as Potential Antioxidant and Anti-Inflammatory Materials for Use as Functional Foods

To assess the potential of by-products of the black bean fermented soybean sauce manufacturing process as new functional food materials, we prepared black bean steamed liquid lyophilized product (BBSLP) and analysed its antioxidant effects in vitro. RAW264.7 macrophages were cultured and treated with BBSLP for 24 h, and 1 μg/mL lipopolysaccharide (LPS) was then used for another 24 h to induce inflammation. The cellular antioxidant capacity and inflammatory response were then analysed. Activation of nuclear factor kappa B (NF-κB) signaling in RAW264.7 macrophages was also analysed. Results showed BBSLP had 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS+) radical-scavenging abilities and reducing power in vitro. The levels of both reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) were reduced after RAW264.7 macrophages were treated with BBSLP after LPS induction. After RAW264.7 macrophage treatment with BBSLP and induction by LPS, the levels of inflammatory molecules, including nitric oxide (NO), prostaglandin E2 (PGE2), IL-1α, IL-6 and TNF-α, decreased. NF-κB signaling activity was inhibited by reductions in IκB phosphorylation and NF-κB DNA-binding activity after RAW264.7 macrophages were treated with BBSLP after LPS induction. In conclusion, BBSLP has antioxidant and anti-inflammatory capabilities and can be a supplement material for functional food.

Metabolic Features of Ganjang (a Korean Traditional Soy Sauce) Fermentation Revealed by Genome-Centered Metatranscriptomics

The taste and quality of soy sauce, a fermented liquid condiment popular worldwide, is greatly influenced by microbial metabolism during fermentation. To investigate the fermentative features of ganjang (a Korean traditional soy sauce), ganjang batches using meju (fermented soybean) bricks and solar salts were prepared, and organic compounds, microbial communities, metagenomes, and metatranscriptomes of ganjang were quantitively analyzed during fermentation. Polymeric compound analysis in the ganjang treated with/without microbial inhibitors revealed that indigenous enzymes of meju bricks might be primarily responsible for degrading polymeric compounds. Through metagenome binning and microbe sequencing, 17 high-quality genome sequences representing all major ganjang microbiota were obtained, and their transcriptional expressions were quantitatively analyzed by mapping metatranscriptome reads normalized by spike-in RNA sequencing to the 17 genomes, which revealed that microbial metabolism might primarily occur while meju bricks are in the ganjang solution and decrease significantly after the removal of meju bricks. Metabolic pathways for carbohydrates, proteins, and lipids of the major ganjang microbiota were reconstructed, and their metabolic genes were transcriptionally analyzed, revealing that facultative lactic acid fermentation by Tetragenococcus was the major fermentation process active in the ganjang fermentation and that aerobic respiration by facultatively aerobic bacteria such as Chromohalobacter, Halomonas, and Marinobacter was also an important metabolic process during fermentation. Although the abundances of Fungi and the corresponding transcriptional expression levels were generally much lower than those of Bacteria, our analysis suggests that yeasts such as Debaryomyces and Wickerhamomyces might be in large part responsible for producing biogenic amines and flavors.

IMPORTANCE The taste and quality of soy sauce, a popular fermented liquid condiment worldwide, is greatly influenced by microbial metabolism during fermentation. Spontaneous fermentation of ganjang (a Korean traditional soy sauce) in a nonsterile environment leads to the growth of diverse bacteria and fungi during fermentation, making it difficult to understand the mechanism of ganjang fermentation. Genome-centered metatranscriptomic analysis, combined with organic compound analysis, quantitative metagenome and metatranscriptome analyses, and metabolic pathway reconstruction and expressional analysis of the major ganjang microbiota during fermentation, would provide comprehensive insights into the metabolic features of ganjang fermentation.

Sodium Reduction in Traditional Fermented Foods: Challenges, Strategies, and Perspectives

Sodium salt is a pivotal ingredient in traditional fermented foods, but its excessive consumption adversely affects human health, product quality, and production efficiency. Therefore, reducing sodium salt content in traditional fermented foods and developing low-sodium fermented foods have attracted increasing attention. Given the essential role of sodium salt in the safety and quality of fermented foods, appropriate approaches should be applied in the production of low-sodium fermented foods. In this review, the challenges of sodium reduction in traditional fermented foods are presented, including the possible growth of pathogenic bacteria, the formation of hazardous chemicals, flavor deficiency, and texture deterioration. Physical, chemical, and biological strategies are also discussed. This review provides references for improving the quality and safety of low-sodium fermented foods.

Diversity of the microbial community and antioxidant activity during fermentation of red raspberry Enzymes

The diversity and succession of microbial community and antioxidant activity present during the preparation of red raspberry Enzymes with and without starter cultures were investigated by high-throughput sequencing of 16S rRNA and ITS1 genes and correlation analysis of the microbial diversity and antioxidant activity. The results showed that the sample inoculated with mixed fermentation had higher antioxidant activity than the sample without inoculated fermentation. The antioxidant capacity of red raspberry Enzymes increased significantly as the fermentation time increased. Firmicutes and Ascomycota were the predominant phyla of bacteria and fungi in all samples. At the genus level, Rhodococcus and Lactobacillus were the predominating bacteria throughout the fermentation process. The genus Kodamaea dominated the fungal community of early-fermentation samples with microbial inoculated fermentation. Candida spp. grew rapidly in the late stage of fermentation in the samples with spontaneous fermentation. Unweighted pair-group and PCA analysis revealed that the microbiota structures differed between the two groups. RDA and CCA showed that Rhodococcus and Kodamaea had positive effects on the DPPH scavenging ability and other antioxidant indicators, and the total phenol content had a significant and positive correlation coefficient with Gluconobacter. The results indicated that the fermentation by microorganisms significantly improves the oxidation resistance and helps to improve the quality of the red raspberry Enzymes.

Effects of flavourzyme addition on physicochemical properties, volatile compound components and microbial community succession of Suanzhayu

Flavourzyme is known to promote protein decomposition, resulting in more peptides and amino acids which can improve the quality of fermented foods. In this study, the effects of flavourzyme addition on the fermentation of Suanzhayu fish were investigated. The results showed that the addition of 50 U/g flavourzyme reduced the water activity (a_w) of products and promoted the release of trichloroacetic acid (TCA)-soluble peptides and free amino acids (FAAs). Thus, the stability of the product was improved and its nutritional value was increased. In addition, with the addition of flavourzyme, Lactobacillus and Saccharomyces more quickly became the dominant genera in the fermentation. Furthermore, the formation of alcohols, aldehydes, and esters was promoted in flavourzyme addition group. Redundant analysis (RDA) indicated that Lactobacillus and Lactococcus play important roles in the formation of flavors, especially for the characteristic flavors of Suanzhayu. Flavourzyme addition may be a novel method to greatly improve the properties of Suanzhayu and shorten the fermentation time.

Enhancement of Agricultural Processed By-Products: Qualities Analysis of Fermentation Method in Gradient Salt Adding Treatment of Tuna Cooking Juice with Black Bean Koji Added

Fish sauce is popular for fermenting food in Southeast and Eastern Asia, while black bean is used to ferment condiments in Taiwan. Researchers have recently investigated the use of fish and black bean sauce in places where combining both fish and black bean is rare. This study was focused on fish sauce made from concentrated tuna cooking juice mixed with black bean koji. The experiment was divided into two stages. In the pre-fermentation stage, a suitable fermentation time with no salt added was determined. In the later fermentation stage, two preformatted samples of 4 and 7 days were added to salt water at 20 °Bé. In the pre-fermentation stage, the results show that the protease activity increased as time passed, but the pH value decreased. The highest browning degree was achieved after 120 days. In the later fermentation period, the total nitrogen contents for both experimental groups of 4 days and 7 days reached up to twice that of soy sauce. The total nitrogen content increased with time. In addition, the level of ammonia nitrogen increased from 0.08 to 0.15 g/dL in the first month. In conclusion, a new flavor of fermented sauce was produced in a shorter time and more effectively by combining tuna cooking juice and black bean.