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Soy sauce, originating from China, has a long history in Asian countries. Recently, global production has markedly increased, and the consumer base is growing. The complex production process, involving various raw materials and multiple steps, poses multiple risks of fraud, some of which are related to food safety. Hence, soy sauce authentication is crucial. This review starts by investigating recent global production and trade volumes of soy sauce in major producing countries. It then outlines production standards and additive usage criteria in key countries. Building on this, it analyzes fraudulent activities observed in soy sauce over the past two decades. Finally, the review introduces principles, equipment, and data processing methods applied in analytical chemistry approaches for studying soy sauce authentication, considering both principles and applications. In soy sauce production, soybean protein hydrolysis relies mainly on microbial fermentation, with an optional use of acid hydrolysis. The latter raises safety concerns, making fraudulent events in soy sauce production through these methods a significant concern. In recent years, soy sauce bottles have displayed various high-quality attribute labels, such as GM-free, organic, addictive-free, and handmade, etc. However, discerning the quality attributes in soy sauce through clear indicators is often very challenging. For the above issues, over the past decade or so, scientists have established a series of targeted and non-targeted analytical methods based on spectroscopy, mass spectrometry, and molecular biology techniques to verify the authenticity of soy sauce. Past research efforts are a good start, however, compared to other foods, the attention given to the authenticity analysis of soy sauce has not matched its importance. Future analytical approaches should focus on sample preparation, developing new rapid detection methods, and establishing chemical profile databases for diverse types of soy sauce. These efforts will further ensure the authenticity of soy sauce sold in many markets across the world. • Soy sauce is a rapidly growing condiment in terms of production and global trade. • Soy sauce fraud is driven by the complexity of ingredients, production techniques, and complex supply chains. • The focus on soy sauce authenticity has not matched its culinary importance. • Putting the spotlight light on soy sauce authenticity analysis advances and future outlooks. [ABSTRACT FROM AUTHOR]

Natto, a nutritious fermented soybean product, is known for its health benefits. Modern production methods use Bacillus subtilis as the starter culture to ensure consistent quality. However, this method overlooks the potential positive effects of other microbial species present in traditionally, naturally fermented natto. This study explored the effects of ARTP-induced mutants of B. subtilis var. natto and several strains of lactic acid bacteria (LAB) on natto quality. The results showed that these two types of bacteria have complementary roles in fermentation. B. subtilis var. natto , with enhanced extracellular protease activity, promotes the hydrolysis of soy protein and enhances the product's ACE inhibitory and fibrinolytic activities. Meanwhile, two strains of Lactiplantibacillus plantarum reduced the content of total volatile basic nitrogen (TVB-N) while increasing the content of folic acid in the final product. In addition, B. subtilis var. natto and LAB produce different profiles of volatile compounds (VOCs). Subsequently, B. subtilis var. natto and Lpb. plantarum were used to co-ferment natto in different ratios. The results showed that the two types of bacteria could co-colonize and enhance fermentation quality through their respective strengths. Specifically, Lpb. plantarum strains co-metabolized with B. subtilis var. natto to elevate the content of pyrazines, characteristic VOCs in natto. The optimal quality of natto was achieved when Lpb. plantarum HIS6, Lpb. plantarum LP3 and B. subtilis var. natto Y15-11 were combined in a 2:1:2 ratio. This study not only identified effective combinations of starter cultures with complementary benefits but also elucidated the metabolic pathways of key volatile compounds. Our findings also provide technical insights for improving natto quality, enhancing consumer acceptance, and supporting industrial production. [Display omitted] • The protease and nattokinase activities of B. subtilis var. natto were enhanced. • Lpb. plantarum and B. subtilis ferment natto with complementary functionalities. • Cofermentation enhances natto quality via metabolic interactions. [ABSTRACT FROM AUTHOR]

Peptide ferrous chelate is a new type of biological iron, which has the advantages of high absorption rate, safety and no digestive tract irritation. In this study, microbial fermentation was used for the first time to prepare iron-chelating peptides. Forty-eight strains were applied to ferment scallop skirts. A dominating strain was eliminated by using the iron binding capacity of the scallop skirt hydrolysate as the screening index. The scallop skirt hydrolysate fermented by Bacillus subtilis M17-b7 showed excellent iron-chelating capacity (96.20% ± 0.03%). Meanwhile, the structure, morphology and bioactivity of fermented scallop skirt hydrolysate (FSH) and fermented scallop skirt hydrolysate-iron (FSH–Fe) were measured. Based on the amino acid composition and spectral analysis, it was confirmed that the significant amino acids contains carboxyl, carbonyl, and amino groups. The result of scanning electron microscope indicated that the surface of FSH became porous and the particles were bigger after chelating with ferrous. Moreover, the peptide-ferrous chelate was more stable in salt solutions and simulated gastric juice compared with ferrous sulfate. It is also noteworthy that the preparation of ferrous chelate peptides by fermentation is cost-effective compared with enzymatic hydrolysis. Therefore, this study provides theoretical support for the use of fermentation as a promising tool to produce peptide-ferrous chelate. [Display omitted] • For the first time, ferrous chelating peptides of seafood were produced via fermentation. • Scallop skirt peptide fermented by Bacillus subtilis M17 b7 has excellent ferrous chelating rate of 10.77 mg/g. • Iron-chelating capacity of the hydrolysates depended on the –COOH and –NH 2. • The peptide-ferrous chelate was more stable in salt solutions and simulated gastric juice compared with ferrous sulfate. • Microbial fermentation was more cost-effective than enzymatic methods. [ABSTRACT FROM AUTHOR]

Kombucha is a kind of traditional fermented sugared tea rich in polyphenols. Although the health effects of tea polyphenols (TPPs) have been extensively studied, the biotransformation of the TPPs during kombucha fermentation was not fully elucidated. In this study, the polyphenol transformation capacity of microbial strains and the synthetic microbial communities during the tea broth fermentation were investigated. Firstly, six microbial species demonstrated different polyphenol transformation abilities: Acetobacter pasteurianus , Zygosaccharomyces bailii and Debaryomyce hansenii could increase the contents of epigallocatechin gallate (EGCG), the most abundant components of TPPs. Z. bailii and Acetobacter xylinum could enhance the concentration of TPPs with low molecular weight. Then, four synthetic microbial communities (SMC) consisting of different species were constructed to ferment the black tea broth. When different strains coexisted, their interaction could further enhance kombucha's phenols transformation and antioxidant activity. Specifically, the SMC, constructed by Z. bailii , L. plantarum and D. hansenii , could enhance the EGCG content significantly in tea broth and the total phenols and flavonoid contents. Meanwhile, the antioxidant activities of kombucha fermented by this SMC were found to be relatively high among different fermented tea broth groups. Besides, it is demonstrated that A. pasteurianus was a strong competitor in the tea broth environment. This bacterium could decrease the number of viable yeast cells by producing more acid. This study demonstrated that the construction of suitable synthetic microbial communities would help reveal the phenolic metabolic characteristics of complex microbial communities and obtain customizable phenolic combinations for kombucha products. [Display omitted] • Microbial strains showed distinct polyphenol transformation capacities. • SMCs further enhance specific phenols and antioxidant activities of kombucha. • Antioxidant activity of kombucha is related to total phenols and phenolic profiles. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of papain on the physicochemical and microbiological properties, volatile compound profiles, and sensorial attributes of Chouguiyu. Papain was applied at a dose of 10, 50, 200, 400 U/g fish. Results showed that papain addition improved the release of free amino acids, essential amino acids, eicosapentaenoi acid (EPA, C20:5n3), and docosapentenoic acid (DPA, C22:5n6), respectively. Lower biogenic amines content, higher the volatile compound concentrations and relative abundance of Lactobacillales were also observed. Further results showed that the papain dose group decreased the fermentation time from 10 to 7 days while good organoleptic quality was remained, especially in the 200 U/g dose group. The redundancy analysis (RDA) showed a high correlation between Lactobacillus and the key volatile compounds in the 200 U/g and 400 U/g groups, which indicated that Lactobacillus could contribute to the fatty flavor. In summary, proper papain addition (i.e. 200 U/g or 400 U/g) could reduce biogenic amines contents and maintain acceptable sensorial properties of Chouguiyu in a shorter fermentation time. [Display omitted] [ABSTRACT FROM AUTHOR]

Chouguiyu (stinky Mandarin fish), a traditional spontaneously fermented fish in China, is famous for its unique aroma and pleasant taste. However, the relationships between the succession of microorganisms during the fermentation and the formation of Chouguiyu 's unique aroma and taste remain to be characterized. In this study, 16S rRNA gene amplicon sequencing was done to investigate the evolving microbiota during Chouguiyu fermentation, and the volatile compounds and amino acids profiles were measured alongside with chemical characterization of the samples (e.g., determination of pH, TVB-N, TBARS, and TCA-soluble peptides). Based on the changes of the microbiota, the fermentation was categorized into two stages: early-fermentation, 1st-3rd days; and late-fermentation, 4th-7th days. Linalool, piperitone, anethole, 1-octen-3-ol, 2-methyl-3-octanone and indole were identified as characteristic volatile compounds in Chouguiyu. According to the sensory evaluation results, the flavor of the Chouguiyu was reinforced in the late-fermentation stage. Redundancy analysis showed the relationships between evolving microbiota and the formation of Chouguiyu 's aroma and taste, and Psychrilyobacter was identified to be the most important bacterial genus contributing to flavor and aroma development, followed by Fusobacterium , Arcobacter and O c eanisphaera. These genera were positively correlated with Glu, Met, Tyr, Pro, linalool, piperitone, indole, TBARS, TVB-N, and TCA, and influenced the flavor and aroma of the Chouguiyu. The results of this study provided a scientific basis to further improve Chouguiyu production. • Chouguiyu 's fermentation process was divided into early-fermentation and late-fermentation. • The changes of features in Chouguiyu were more pronounced during the late-fermentation stage. • Four genera were found to be highly related to the change of Chouguiyu' s flavor and aroma. • These 4 genera included Psychrilyobacter , Fusobacterium , Arcobacter and Oceanisphaera. • The Psychrilyobacter was highly related to the flavor and aroma of Chouguiyu. [ABSTRACT FROM AUTHOR]

Decanal is one of the main products of lipid oxidation. It has been shown that decanal can oxidize to form volatiles with shorter carbon chains during heating, but the mechanism is still unclear. In this study, volatile compounds formed in the decanal thermal oxidation were verified using thermal-desorption cryo-trapping combined with GC–MS. A total of 32 volatile compounds were identified. The oxidation mechanism of decanal was studied by applying density functional theory. Results revealed that the carbonyl carbon atom was the thermal oxidation site of decanal and two pathways of peroxide oxidation were determined: the ortho‑carbon and the meta‑carbon oxidation. The ortho‑carbon oxidation pathway is superior to the occurrence of the meta‑carbon oxidation pathway. The oxidative mechanism of decanal was finally summarized as the peroxide oxidation based on radical attack on the carbonyl carbon, which would provide a theoretical basis for exploring the oxidation mechanism of other saturated aldehydes. [Display omitted] • Carbonyl carbon atom was the thermal oxidation site of decanal. • Oxidative cleavage of decanal was caused by peroxides formed by free radical attack. • Ortho‑carbon and meta‑carbon oxidation pathways were elaborated. • Priority order was ortho‑carbon oxidation pathway > meta‑carbon oxidation pathway. [ABSTRACT FROM AUTHOR]

Iron chelating peptides have been widely utilized as iron supplements due to their excellent absorption capacity, However, the high cost and cumbersome manufacturing process of these peptides significantly limit their industrial application. In this study, fermentation was used for the first time to prepare iron chelating peptides. Bacillus altitudinis 3*1–3 was selected as the most suitable strain from 50 strains. The hydrolysates of fermented scallop skirts showed excellent iron-chelating capacity (9.39 mg/g). Aspartic acid, glutamic acid, and histidine are crucial for the binding of peptides to ferrous ions. The heptapeptide (FEDPEFE) forms six binding bonds with ferrous irons. Compared with ferrous sulfate, peptide-ferrous chelate showed more stability in salt solution and simulated gastrointestinal juice (p < 0.05). Furthermore, the fermentation method could save >50% of the cost compared with the enzymatic method. The results can provide a theoretical basis for the preparation of ferrous-chelated peptides using the fermentation method. [Display omitted] • For the first time, seafood-ferrous chelates were prepared by fermentation. • Fermented hydrolysates showed a high iron chelating rate of 9.39 mg/g. • Aspartic acid, glutamic acid, and histidine are crucial for binding to ferrous ions. • Spatial structures of peptides are important for the chelating of iron and peptides. • The heptapeptide (FEDPEFE) forms six binding bonds with ferrous iron. [ABSTRACT FROM AUTHOR]

In this study, the electrospinning technique was used to co-encapsulate Quercetin (Qu) and Lactiplantibacillus plantarum 1–24-LJ in PVA-based nanofibers, and the effect of bioactive films on fish preservation was evaluated at the first time. The findings indicated that both Lpb. plantarum 1–24-LJ and Qu were successfully in the fibers, and co-loaded fibers considerably outperformed single-loaded fiber in terms of bacterial survival and antioxidant activity. Following fish preservation using the loaded fibers, significant reductions were observed in TVB-N, TBARS, and microbial complexity compared to the control group. Additionally, the co-loaded fibers more effectively reduced the counts of H 2 S-producing bacteria and Pseudomonas. In the future, fibers with both active substances and LAB hold promise as a novel approach for fish preservation. [Display omitted] • Co-loading of flavonoids quercetin (Qu) and Lpb. plantarum by electrospinning technology. • Qu and Lpb. plantarum synergize provide strong antioxidant and hyper-bacterial activity. • Qu or/and Lpb. plantarum films inhibit the growth of spoilage bacteria. • Active films improved fish's physiology, raised sensory appeal and extended storage time. [ABSTRACT FROM AUTHOR]

It's the first comparative transcriptome study of Tetraselmis subcordiformis' H 2 production with carbonyl cyanide m-chlorophenylhydrazone (CCCP) by de novo RNA-seq. The global analysis of the annotated genes and pathways unveiled it a good candidate for biofuels. Focusing on H 2 production, the genes coding active center subunit (HydA) and assembly subunits (HydEF and HydG) of hydrogenase proportionally expressed during the induction but stopped after illuminated; on contrast, the gene of the active centre stabilization subunit (Hyd3) highly expressed during the H 2 evolution, indicating its key role in the prolonged H 2 production. The results also showed genes of HCP4, ppGpp phosphohydrolase and RpoD relating to the hydrogenase expression regulation. On the energy aspect, genes of CF-ATPases and ferredoxin-NADP reductase in chloroplast down-regulated while Mito-ATPase in mitochondria and pyruvate metabolism pathway up-regulated during the H 2 production, consisting with our previous reports on physiological level. [ABSTRACT FROM AUTHOR]

[Display omitted] • Untreated molasses could be utilized by R. mucilaginosa DL-X01 as carbon source. • Fish bone meal enzymatic hydrolysate was used to replace yeast extract and peptone. • The amount of molasses and fish bone meal added were optimized. • Feedstock cost of producing EGT is reduced by 331 % compared to using YPD broth. Ergothioneine (EGT) is a high-value natural antioxidant that cannot be synthesized by the human body. This study showed that Rhodotorula mucilaginosa DL-X01 can use untreated molasses and fish bone meal enzymatic hydrolysate as the substrates to synthesize EGT. By optimizing the growth conditions, the EGT yield reached 29.39 mg/L when molasses and fish bone meal (FBM) were added at 60 g/L and 400 g/L respectively. Finally, the EGT yield was increased to 216.25 mg/L by fed-batch fermentation in a 5 L bioreactor. Compared with the fermentation by yeast extract peptone dextrose medium, the feedstock cost of EGT production was reduced by 330.91 % by using molasses and FBM as substrates. These results showed that R. mucilaginosa DL-X01 can produce high-value EGT using two cheap processing by-products, molasses and FBM, which is of great significance for environmental protection and sustainable development. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal oxidation mechanism of (E)−2-decenal was discussed by applying DFT. • Obtained reactions grouped into peroxide, alkoxy radical, peroxyl radical pathway. • Priority order is alkoxy radical > peroxide > peroxyl radical pathway. Unsaturated fatty aldehydes are the main products of fatty acid oxidation, and could be further oxidized to form volatile compounds with shorter carbon chains. Therefore, studying the oxidation of unsaturated fatty aldehydes is an important way to reveal the mechanism of food flavor formation during heating. In this study, volatile profiling of (E)-2-decenal during heating was firstly investigated by using thermal-desorption cryo-trapping combined with gas chromatography-mass spectrometry (GC–MS). A total of 38 volatile compounds were detected. Then, twenty-one reactions in the heating process of (E)-2-decenal were obtained by using density functional theory (DFT) calculations, and grouped into three oxidation pathways, namely, peroxide pathway, peroxyl radical pathway and alkoxy radical pathway. Meanwhile, the priority of these three pathways was the alkoxy radical reaction pathway > peroxide pathway > peroxyl radical reaction pathway. Moreover, the calculated results agreed well with the experimental results. [ABSTRACT FROM AUTHOR]

Abstract Manufacturing of protein-enriched beverages is an interesting field which has attracted a lot of attention from the research community. In this study, polysaccharides extracted from a mushroom (Tremella fuciformis) were used to enhance the stability of 5% whey protein isolate (WPI) solution for enriched beverage development with excellent results. Rheological studies showed that the T. fuciformis polysaccharides (TP) enhanced WPI solution exhibited characteristics of pseudoplastic fluid. Microstructure studies showed that the WPI–TP complexes formed more orderly structures than that of the two monomers. A new limited proteolysis-coupled mass spectrometry technique was utilized to characterize the in vitro digestibility of WPI-TP complexes: the rate of digestion of WPI-TP was shown to be significantly lower than that of WPI, which would reduce gastric emptying time and increase satiety. In addition, the degree of digestibility of each protein and the potential binding regions of TP-WPI were also revealed by this new technique. Graphical abstract Image 1 Highlights • Polysaccharides (TP) from a fungus enhance the stability of 5% WPI solution. • WPI–TP complexes formed more orderly microstructures. • A new LiP-MS technique was developed to characterize its digestibility. • The potential binding regions of TP and WPI were revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probiotics and phycocyanin (Pc) were co-embedded in nanofibres (NFs) the first time. • The survivability of L. plantarum 1-24-LJ in fiber was significantly enhanced by Pc. • Electrospun fibers protect the Pc' bioactivity, while probiotics boost its loading. • Co-addition of Pc and probiotics markedly enhance the fibers' antioxidant ability. • NFs containing symbiotic additives are innovative materials for food preservation. This study reports for the first time the co-encapsulation of probiotics and phycocyanin by electrospinning. SEM showed that the electrospun fibers exhibited a homogeneous, smooth surface and a circular shape. XRD and ATR-FTIR results showed that Lactiplantibacillus plantarum 1-24-LJ and Pc were co-embedded in the fibers and that the presence of L. plantarum 1-24-LJ promoted the encapsulation of phycocyanin. TG analysis showed that the addition of phycocyanin and L. plantarum 1-24-LJ improved the composite fiber's thermal stability. The fibers co-embedded with phycocyanin and L. plantarum 1-24-LJ had the highest DPPH and ABTS+ activity, indicating that the two may have synergistic antioxidant effects. After 28 days, the viability of the strain could still be above 6 log cfu/g, and the addition of phycocyanin could help to improve the strain's survivability. In this experiment, a co-embedding method for probiotics and antioxidants was proposed, which could effectively increase the survivability of probiotics and improve the antioxidant properties of the fibers. [ABSTRACT FROM AUTHOR]

[Display omitted] • C. zeylanoides and S. cerevisiae were firstly reported as major fungi in sour meat. • S. cerevisiae was positively related to esters, alcohols and total flavor compounds. • The addition of S. cerevisiae could improve the sensory quality of sour meat. Saccharomyces cerevisiae is commonly used as a starter culture for alcoholic beverages but is less applied in meat products. In this study, the effects of S. cerevisiae LXPSC1 on sour meat during fermentation were investigated. It was found that samples inoculated with S. cerevisiae LXPSC1 (Sc group) had better sensory characteristics and higher levels of pH, ethanol, free amino acids (FAAs), volatile organic compounds (VOCs). The bacterial communities of both groups were dominated by Lactobacillus sakei , Weissella hellenica , and Lactobacillus plantarum , which might play a role in reducing pH and a w and increasing the content of lactic acid, FAAs, and esters. However, Candida zeylanoides and S. cerevisiae were the dominant fungi in the control group and Sc group, respectively. Moreover, S. cerevisiae was positively related to esters, alcohols, ethanol and total VOCs. Overall, S. cerevisiae LXPSC1 might be regarded as a desirable starter culture for improving product quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • 72 amine degrading bacterial isolates were obtained. • Two LAB starters with MCO activity could effectively reduce BAs in Roucha. • Mixed starters had higher a higher reduction (46.64%) of total BAs in Roucha. • L. plantarum as dominant population was beneficial to volatile profiles of Roucha. • Starters in Roucha resulted in a marked decrease of BAs-producing bacteria. Biogenic amines (BA) are often present at high concentrations in fermented meat and cause foodborne illness. The aim of this work was to screen amine-degrading starters for Roucha (a fermented meat) to improve product safety and quality. Firstly, Weissella viridescens F2 and Lactiplantibacillus plantarum His6 with multi-copper oxidase activity and high degradation rates towards histamine and tyramine were selected as single or mixed starters. Additionally, the effect of starters on bacterial community succession, acid production, BA accumulation, free amino acid profiles, and volatile compound profiles were evaluated during the fermentation of Roucha. Results indicated that all starters could effectively reduce the accumulation of BA in Roucha. At the end of fermentation, Lpb. plantarum His6 as a single starter reduced the histamine level (38.15 %), while mixed starters (Lpb. plantarum His6 + W. viridescens F2) possessed a high tyramine-reduction rate (54.95 %) and total BA-reduction rate (46.64 %). Bacterial succession analysis revealed that starters could help establish the dominance of lactobacilli or Weissella quickly, which contributed to the direct degradation of BA and inhibited the growth of amine-producing bacteria. Furthermore, Lpb. plantarum His6 could promote the accumulation of essential amino acids (leucine, phenylalanine, threonine, isoleucine), sweet and umami amino acids (glycine, threonine, glutamate), and volatile compounds of good odor, indicating that this strain greatly contributed to the development of good taste and aroma characteristics in Roucha. Overall, this work shows that the application of amine-degrading starters is an effective strategy to reduce the BA accumulation and improve the quality of Roucha. Thus, these findings can provide foundations for the industrial production of Roucha. [ABSTRACT FROM AUTHOR]

[Display omitted] • The co-inoculated Suancai had a high bacterial diversity. • The inoculation of Lb. plantarum and P. pentosaceus changed the VCs profiles. • The co-inoculation of Suancai had a similar VCs profile with spontaneous Suancai. • The inoculation increased the organic acids and most of amino acids of Suancai. The quality characteristics of Suancai fermented with Lactobacillus plantarum CGMCC No.20193 (Lb. plantarum) and Pediococcus pentosaceus CGMCC No. 20192 (P. pentosaceus) were investigated. Their inoculation affected the bacterial communities revealed by Pacbio Sequel platform. After fermentation, the dominant phylum and genus in inoculation and spontaneous fermented Suancai were Firmicutes and Lactobacillus. Compared with single inoculation, the co-inoculation of Lb. plantarum and P. pentosaceus had a higher bacterial diversity. The Suancai co-inoculated with Lb. plantarum and P. pentosaceus had a more similar VCs profile with spontaneous fermented Suancai. The inoculation of Lb. plantarum and P. pentosaceus increased the content of organic acids, such as lactate, acetate, citrate, succinate, malate and tartrate. The most amino acids content in Suancai fermented with Lb. plantarum and P. pentosaceus were higher than that in spontaneous fermented Suancai. Compared single inoculation, the Suancai co-inoculated with Lb. plantarum and P. pentosaceus had a higher similarity of organoleptic tastes with spontaneous fermented Suancai. These results may facilitate the understanding of the starters' effects on the Suancai fermentation and the selection of applicable starters to manipulate the flavor. [ABSTRACT FROM AUTHOR]

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. • The addition of 50 U/g flavourzyme help prolong the shelf life and increased the nutritional value. • Lactobacillus and Saccharomyces were easier to establish dominant position with flavourzyme addition. • Flavourzyme addition prompted the formation of alcohols, aldehydes, and esters. • Lactobacillus and Lactococcus played important roles in the flavor formation. • Flavourzyme addition may be a novel method that can potentially improve the properties of Suanzhayu. [ABSTRACT FROM AUTHOR]

• Firmicutes and Cyanobacteria were major phylum in Suancai. • Lactobacillus and Pediococcus were the biomarker of LS and HS, respectively. • Lactobacillus and Pediococcus were correlated with flavors in Suancai. • The inoculated of P. pentosaceus improve the alcohols and nitriles in Suancai. • The co-inoculated of L. plantarum and P. pentosaceus improve the flavors in Suancai. Suancai, a popular traditional fermented cabbage in northeast China, is commonly prepared by the spontaneous fermentation process at a certain salt concentration. The salt can affect the metabolites by affecting the microorganisms during Suancai fermentation. The bacterial community and volatile flavor compounds in commercial Suancai from different regions of Northeastern China at different salt concentrations were investigated using next-generation sequencing and GC–MS. Firmicutes and Cyanobacteria were the dominant phyla in the commercial Suancai, and Lactobacillus , Pediococcus , and Leuconostoc were the dominant genera. Among them, Lactobacillus and Pediococcus were considered as the biomarkers of the low and high salt Suncai, respectively. Eighty-five volatile flavor compounds were detected, and HS exhibited higher contents of volatile flavor compounds than LS. Based on the results of correlation analysis, Pediococcus were highly correlated with the alcohols and nitriles in Suancai. The contents of alcohols and nitriles significantly increased in the Suancai, fermented by Pediococcus pentosaceus. The co-inoculated fermentation of Lactobacillus plantarum and P. pentosaceus could increase the concentrations of alcohols, esters, aldehydes, hydrocarbons, and nitriles in Suancai. This study provides a perspective for understanding the ecology of Suancai fermentation and facilitating the fermentation with multispecies inoculation fermentation at an appropriate salt concentration. [ABSTRACT FROM AUTHOR]

This paper aimed to investigate the dose-effects of l -Lysine (Lys, 0.2% to 0.8%) on the water holding capacity (WHC), textural properties, water mobility and distribution, microstructures and sensory acceptance of reconstructed ham with 50% reduction of added salt. Results showed that reducing salt from 2.50% to 1.25% caused significant increase in cooking loss and centrifuge loss, and decrease in hardness, springiness and chewiness. 0.8% Lys significantly improved the WHC and textural properties of salt-reduced hams, whereas 0.2% Lys further impaired these attributes. Moreover, 0.8% Lys improved the sensory scores for mouthfeel, appearance, taste and global acceptance. The NMR analysis reveals that water distribution and mobility were affected by salt reduction and Lys addition, and hams with 0.8% Lys contained more entrapped water with decreased mobility. Furthermore, a fine network with more bridge-linkage among myofibrils was formed in hams with 0.8% Lys. Therefore, addition of 0.8% Lys showed great potential in developing salt-reduced reconstructed ham with premium technological and sensory qualities. [ABSTRACT FROM AUTHOR]

This study was designed to explore the temperature effects on bacterial communities and metabolites, as well as their relationships during the fermentation of sour meat, a traditional fermented meat product in the ethnic minority regions of China. Results showed that reduction of pH and increase of lactic acid and free amino acid contents occurred (p < 0.05) as the fermentation temperature and time increased, and the tendency was more apparent at higher temperature. During the fermentation, Lactobacillus gradually replaced other genera, and higher the temperature, more rapid was the process. Both the number and amount of volatile organic compounds increased at higher temperatures. Hexanal, benzaldehyde, nonanal, (E,E)-2,4-decadienal, 1-octen-3-ol and octanal were identified as the key volatile organic compounds produced by Lactobacillus in sour meat as main contributors to odor as confirmed by variable importance in the projection analysis. Redundancy analysis and Pearson correlation showed positive correlation between Lactobacillus and desired product characteristics, such as higher content of lactic acid, free amino acids, volatile organic compounds, and lower pH and water activity values, which may represent a better quality and longer shelf life after fermentation at higher temperature. Therefore fermentation at 20 °C and 25 °C are proposed as optimum temperatures for sour meat production. • Faster fermentation process of sour meat were obtained at higher temperatures (20 °C and 25 °C). • There were more abundant metabolites in batches of higher fermentation temperatures. • Lactobacillus was the dominant genus eventually. • Lactobacillus was positively related to the desirable quality and flavor of sour meat. [ABSTRACT FROM AUTHOR]