Improving the taste profile of reduced-salt dry sausage by inoculating different lactic acid bacteria

Elucidating the pattern of flavor evolution during the steaming process of fermented sausages in two dimensions: Strain fermentation and steaming time

This study elucidated the pattern of change in flavor during the steaming of fermented sausages, with a particular focus on the influence of two key factors: Strain fermentation and steaming time. The results indicated that the steaming procedure resulted in a notable loss of water, as well as protein and fat oxidation, in fermented sausages. Additionally, flavor compounds, predominantly aldehydes, esters, and Maillard reaction products, were produced in considerable quantities during the steaming of sausages. Notably, fermented sausages inoculated with LS starter (Lactiplantibacillus plantarum CQ 01107 and Staphylococcus simulans CD 207) exhibited lower levels of oxidation and higher contents of free amino acids and free fatty acids. Furthermore, the textural characteristics of LS sausages during steaming were found to be more favorable, as were the flavor compounds content and sensory scores. For 30-min steaming, LS sausages exhibited lower hardness and chewiness, accompanied by higher levels of esters, ketones and aldehydes, and better sensory scores. These findings demonstrate that starter culture selection (particularly LS strains) and 30-min steaming synergistically optimize flavor profiles, provides a scientific foundation for enhancing the flavor characteristics of fermented sausages throughout their journey from the factory production to the consumer's table.

Inoculation with autochthonous yeast strains in Harbin dry sausages with partial substitution of NaCl by KCl: Bacterial community structure and flavour profiles

The effects of two autochthonous yeast strains (Pichia kudriavzevii and Debaryomyces hansenii) on the physicochemical characteristics, bacterial community structure, and flavour profile of the dry sausages with 40% substitution of NaCl by KCl were evaluated in this study. The results revealed that the inoculation of yeast strains increased the pH and yeast counts of low-sodium sausages. Higher contents of total esters, aldehydes, and ketones were detected in the inoculated sausages (P < 0.05). Based on the results of high-throughput sequencing, the inoculation of P. kudriavzevii decreased the abundance of Lactobacillus, Weissella, and Leuconostoc. However, the inoculation of D. hansenii increased the abundance of Lactobacillus, Weissella and Staphylococcus, which may help to inhibit the growth of pathogenic microorganisms in sausages. Electronic tongue analysis as well as sensory evaluation revealed that D. hansenii reduced bitter, astringent, and metallic tastes (P < 0.05). Overall, D. hansenii can be used as the prospective stater culture to compensate the flavour defects and improve the safety of the dry sausage with NaCl substitutes.

Use of Selected Environmental Lactic Acid Bacteria During Industrial Production of Heat-Treated Nitrite-Free Organic Sausage

This study aimed to evaluate the potential of lactic acid bacteria (LAB) isolated from organic acid whey as an alternative to nitrites in heat-treated organic sausages. Eleven LAB strains were screened for their ability to develop sensory characteristics similar to traditionally cured meat. Based on the results, Lactiplantibacillus plantarum S21 was selected for further experiments. Four sausage treatments were produced: control cured (C), salted (S), salted with L. plantarum S21 at 107 CFU/g (LP), and salted with acid whey (AW). The pH value, oxidation-reduction potential (ORP), antioxidant activity of peptides (ABTS•+), thiobarbituric acid-reactive substance (TBARS), fatty acid profile, and microbiological quality were assessed post-production and after 14 days of cold storage. After production, the LP and AW sausages had a lower pH than the cured (C) and uncured (S) control samples. LP sausages exhibited a stable pink colour due to myoglobin conversion to nitrosylmyoglobin, comparable to the cured control. The LP sausages were similar in overall sensory quality to the cured (C) samples and were superior to the S and AW sausages after storage. The lowest ORP value was observed in treatment C after production, whereas after storage, no significant differences were found between the treatments. The highest antioxidant activity of peptides was observed in the LP sausages. It was shown that the LP and AW treatments had lower saturated fatty acid content and higher monounsaturated and polyunsaturated fatty acid content than the C and S treatments. Nevertheless, the C treatment had the lowest TBARS value. Lower total viable counts were found in the C and LP treatments than in the S and AW treatments after storage. Our research demonstrates the potential of L. plantarum S21 for producing heat-treated sausages without nitrites, assuming the implementation of additional anti-botulinum barriers. Nevertheless, further studies on the role of bacteria in meat oxidation processes are needed.

Mechanism of salt effect on flavor formation in Lactiplantibacillus plantarum fermented tilapia: integrated multiple intelligent sensory and flavor omics analyses

Improving the flavor and texture of low-salt fermented products addresses the demands of the health-conscious era and consumers' preferences. In this study, the characteristic flavor formation of dry-cured tilapia fermented by Lactiplantibacillus plantarum with different concentrations of NaCl was studied using flavor omics. The results showed that an appropriate concentration of NaCl improved the sensory and texture properties of the product. The 4% NaCl concentration increased the aroma intensity of the fermented tilapia. Under the action of 4% salt, the metabolism of Lactiplantibacillus plantarum promoted the formation of alcohols and aldehydes. The concentrations of 1-octen-3-ol and hexanal were significantly increased, enhancing the aroma of roasted meat. Meanwhile, low NaCl treatment promoted Lactiplantibacillus plantarum to degrade proteins and convert them into more free amino acids and nucleotides. Fermentation of tilapia with 4% salt significantly promoted the production of umami and sweet amino acids, such as glutamic acid and glycine. Additionally, it inhibited the production of bitter amino acids, such as leucine. Furthermore, the results contribute to a better understanding of the effects of NaCl on flavor formation in fermented tilapia and facilitate the development of flavor in low-salt foods.

Impact and correlation of fermentation temperature on the bacterial community, flavor characteristics, and proteolysis of Harbin dry sausages

Proteins undergo degradation to produce peptides and free amino acids, which in turn promote the production of volatile compounds with important contributions to the taste and aroma. This study investigated the effect of fermentation temperatures (8, 15, and 25 °C) on the bacterial community, flavor profile, and protein degradation of Harbin dry sausages. The physical and chemical properties were improved at 25 °C compared with 8 and 15 °C. Staphylococcus xylosus increased with the increase in fermentation temperature, whereas Latilactobacillus sakei decreased. The degree of protein degradation increased, and the content and proportion of taste peptides and free amino acids increased. Similarly, a higher fermentation temperature led to an increase in volatile compounds, such as aldehydes, alcohols, and esters. In conclusion, there is an inseparable relationship between proteolysis and microbial proteases. The fermentation temperature of 25 °C best contributed to the sensory quality and flavor characteristics of Harbin dry sausages.

Textured vegetable protein as a partial replacement for lean meat in salami analogues: Perspectives on physicochemical properties, flavour and proteome changes

Integrating plant proteins into meat products offers a sustainable way to reduce the environmental impact of meat consumption while satisfying the growing flexitarian population. This study explored the effects of textured vegetable proteins (TVPs) on the physico-chemical attributes and flavour profile of hybrid salamis using 4D label-free proteomics. Results showed that hybrid salamis had lower pH, reduced water activity and increased weight loss compared with traditional salamis, along with greater hardness and a slightly rough, porous texture with a filamentous structure. TVPs substantially modified crucial meaty flavour compounds (nitrogen oxides, sulfides and pyrazine), increasing heightening sourness and bitterness while diminishing umami. Proteomic analysis revealed significant upregulation of myosin and actin in hybrid salamis; notably, these proteins were involved in glycerol-3-phosphate dehydrogenase activity and calcineurin-mediated signalling, underscoring their role in flavour enhancement. Therefore, hybrid salamis offer an attractive alternative to traditional salamis by merging meat-like taste and texture with plant protein.

Unraveling the potential of zinc protoporphyrin-forming lactic acid bacteria for replacing nitrite and their role in quality characteristics of Harbin dry sausage

This study evaluated the effects of zinc protoporphyrin-producing lactic acid bacteria specifically Weissella viridescens JX11, Weissella viridescens MDJ8, and Lactobacillus pentosus Q on nitrite substitution and the quality characteristics of Harbin dry sausage. The redness (a*) values in the bacteria-inoculated groups were significantly higher than those in the control group (P < 0.05) during fermentation. Bacteria-inoculated sausages exhibited a higher proportion of oxymyoglobin and a lower proportion of metmyoglobin (P < 0.05). Ferrochelatase activity in the inoculated groups was significantly higher than in the control at days 3 and 6 (P < 0.05). Additionally, the fluorescence intensity of zinc protoporphyrin and its precursor, protoporphyrin IX, in the bacteria-inoculated groups significantly increased during fermentation (P < 0.05), and W. viridescen JX11 exhibited the highest fluorescence intensity and UV-Vis absorption peak (P < 0.05). These results suggest that zinc protoporphyrin-producing lactic acid bacteria could potentially replace nitrite in fermented dry sausages.

Safety and Quality Improvement of NaCl-Reduced Banana and Apple Fermented with Lacticaseibacillus paracasei

Food preservation techniques changed during the industrial revolution, as safer techniques were developed and democratized. However, one of the simplest techniques, adding salt, is still employed in a wide variety of products, not only as a flavor enhancer but as a method to allow for the controlled fermentation of products such as fruits. The objective of the present study consists of evaluating the quality of different salt-reduced fermented fruits through the application of the lactic acid bacteria (LAB) Lacticaseibacillus paracasei and vacuum, as well as assessing the LAB as a preventive measure against Escherichia coli O157:H7. To achieve this goal, microbial plate count techniques, the evaluation of the physicochemical characteristics, and Check-All-That-Apply/Rate-All-That-Apply sensory analyses were performed on bananas and apples individually fermented at 30 °C for 2 and 7 days, respectively. Additionally, a challenge test using E. coli as pathogenic bacteria was performed. The characteristics of each fruit determined the efficiency of the LAB's protective activity. LAB-inoculated batches controlled the growth of E. coli in both salted fruits, but this pathogenic bacterium in the apple case was controlled even in the salt-reduced batch. Sensorially, only inoculated fermented apples found a reduction in off-flavor and old fruit smell; however, higher acceptability was found in the salt-reduced with LAB batches of both fruits. Thus, Lacticaseibacillus paracasei proved to be a cheap, easy, and feasible protective method that can ensure a protective strategy on salt-reduced fermented apples and should be studied particularly for different fruits.

Comparison of non-volatile compounds of Penaeus vannemei with different drying treatments via multidimensional infrared spectroscopy

To analyze the effect of various drying treatments (microwave drying (MD), hot air drying (HAD), vacuum drying (VD), and vacuum freeze drying (VFD)) on taste compounds in Penaeus vannamei, relevant indicators such as free amino acids, 5'-nucleotides, and organic acids were performed. Multidimensional infrared spectroscopy (MM-IR) results found that there were notable variations in taste properties of P. vannamei. There were 18 autocorrelation peaks in 3400-900 cm-1 were screened using second-derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR). Variations in functional groups were the major contributors to taste profiles. The TAV of glutamic acid (Glu), guanine (GMP), and inosinemonphosphate (IMP) were greater than one and had notable impacts on taste profiles. VD had the highest equivalent umami value, followed by VFD, HAD, and MD. This study may provide a theoretical guide for the production of dried P. vannamei products on an industrial scale.

Effect of glycine and Pediococcus pentosaceus R1 combined application on the physicochemical properties, oxidative stability, and taste profile of Harbin dry sausages

This study investigated the effects of the application of glycine (Gly) and Pediococcus pentosaceus R1(Pp), alone or in combination, on the physicochemical properties, oxidative stability, and taste quality of Harbin dry sausages. The results demonstrated that after nine days of fermentation, the Gly + Pp group exhibited significantly (P < 0.05) lower moisture content (19.04%), water activity (0.686), and pH (4.78) values, alongside notably (P < 0.05) higher lactic acid bacteria count (8.11 log CFU/g sausage) and redness value (17.2), compared to the other three groups (P < 0.05). In addition, the dry sausages in the Gly + Pp group exhibited the lowest peroxide value (0.34 meq/kg sausage), thiobarbituric acid reactive substances (0.46 MAD/kg sausage), and protein carbonyl content (1.26 nmol/kg protein) during fermentation, followed by the Gly group, Pp group, and control group. Electronic tongue (e-tongue) and sensory evaluations revealed that the combined treatment with P. pentosaceus R1 and Gly resulted in superior taste characteristics. Besides, partial least squares regression (PLSR) analysis illustrated that the taste qualities characterized using the e-tongue were accordant with the sensory evaluation consequences, and total free amino acids (FAAs) and organic acids contributed to the dry sausages' taste properties. In conclusion, the combined application of Gly and P. pentosaceus R1 enhanced the physicochemical properties, oxidative stability, and taste profile of Harbin dry sausages.

Blue honeysuckle fermentation with Lacticaseibacillus rhamnosus L08 improves its biological activity, sensory and flavor characteristics, and storage stability

The objective of this study was to investigate the potential of Lacticaseibacillus rhamnosus L08 (L. rhamnosus L08) to enhance the functionality, improve the taste, and explore efficient storage methods of blue honeysuckle juice (BHJ). The fermentation process resulted in an increase in the levels of polyphenols, flavonoids, and anthocyanins in blue honeysuckle juice, which was attributed to the action of β-glucosidase on specific phenolic compounds, namely Cyanidin-3-Glucoside and Quinic acid. The increase in phenolic content resulted in an enhancement of the antioxidant capacity of BHJ. The fermentation processed, utilizing L. rhamnosus L08, not only enhanced the flavor and taste of BHJ, but also mitigated its bitter aftertaste while minimizing the loss of bioactive components during storage. In conclusion, this study demonstrated a potential avenue for enhancing the commercial value and dietary significance of this lesser-known superfruit, with fermented BHJ emerging as a promising innovation in the field of functional foods.

Research Progress on the Mechanism of the Impact of Myofibrillar Protein Oxidation on the Flavor of Meat Products

Myofibrillar proteins primarily consist of myosin, actin, myogenin, and actomyosin. These proteins form complex networks within muscle fibers and are crucial to the physical and chemical properties of meat. Additionally, myofibrillar proteins serve as significant substrates for the adsorption of volatile flavor compounds, including aldehydes, alcohols, ketones, and sulfur and nitrogen compounds, which contribute to the overall flavor profile of meat products. A series of chemical reactions occur during the processing, storage, and transportation of meat products. Oxidation is one of the most significant reactions. Oxidative modification can alter the physical and chemical properties of proteins, ultimately impacting the sensory quality of meat products, including flavor, taste, and color. In recent years, considerable attention has been focused on the effects of protein oxidation on meat quality and its regulation. This study investigates the impact of myofibrillar protein oxidation on the sensory attributes of meat products by analyzing the oxidation processes and the factors that initiate myofibrillar protein oxidation. Additionally, it explores the control of myofibrillar protein oxidation and its implications on the sensory properties of meat products, providing theoretical insights relevant to meat processing methods and quality control procedures.

Advancements in production, assessment, and food applications of salty and saltiness-enhancing peptides: A review

Salt is important for food flavor, but excessive sodium intake leads to adverse health consequences. Thus, salty and saltiness-enhancing peptides are developed for sodium-reduction products. This review elucidates saltiness perception process and analyses correlation between the peptide structure and saltiness-enhancing ability. These peptides interact with taste receptors to produce saltiness perception, including ENaC, TRPV1, and TMC4. This review also outlines preparation, isolation, purification, characterization, screening, and assessment techniques of these peptides and discusses their potential applications. These peptides are from various sources and produced through enzymatic hydrolysis, microbial fermentation, or Millard reaction and then separated, purified, identified, and screened. Sensory evaluation, electronic tongue, bioelectronic tongue, and cell and animal models are the primary saltiness assessment approaches. These peptides can be used in sodium-reduction food products to produce "clean label" items, and the peptides with biological activity can also serve as functional ingredients, making them very promising for food industry.

Smoked sausages of bovine meat produced in North Macedonia as a source of pro-technological lactic acid bacteria and coagulase-negative cocci

Smoked bovine sausages, traditional meat products from the Balkan Peninsula, are rich in microbial diversity and represent potential sources of pro-technological microorganisms. This study aimed to characterize these sausages from three different producers collected in green markets of North Macedonia. The analyses included physico-chemical (proximate composition, pH, aw), morpho-textural (color and texture), and microbiological assessments (viable plate counts). Moreover, an isolation campaign was conducted to identify and characterize pro-technological microorganisms. Significant variability was observed in moisture content (ranging from 33.70 to 48.61 %), hardness, and color among samples from different producers. Samples from producer 2 showed the lowest pH (mean ∼4.90) and the highest loads of lactic acid bacteria (up to ∼9 log cfu g-1). Coagulase-negative cocci ranged between 4.84 and 7.47 log cfu g-1. No potential pathogenic bacteria were detected. A total of 30 isolates, primarily Latilactobacillus sakei, Staphylococcus equorum, and Staphylococcus casei, were identified. Isolates of L. sakei S7, S13, and S27 showed strong in-vitro acidification performance, together with the production of exopolysaccharides (EPS), and protease activity. S. equorum isolates S1 and S2 exhibited protease and lipase activities, while isolates S. casei S21 and S28 showed notable lipase and protease activities, along with the production of EPS. Additionally, all S. equorum isolates, except S2, showed nitrate reductase activity, one of the key features able to affect sausage color. These findings highlighted the pro-technological traits of these microbial isolates, suggesting their potential use as starter or adjunct cultures in the meat industry to enhance product quality and safety.

Comparative Analysis of Commercially Available Flavor Oil Sausages and Smoked Sausages

This study utilized gas chromatography-ion mobility spectrometry (GC-IMS) to analyze the volatile flavor compounds present in various commercially available sausages. Additionally, it conducted a comparative assessment of the distinctions among different samples by integrating sensory evaluation with textural and physicochemical parameters. The results of the GC-IMS analysis showed that a total of 65 volatile compounds were detected in the four samples, including 12 hydrocarbons, 11 alcohols, 10 ketones, 9 aldehydes, 12 esters, and 1 acids. Fingerprinting combined with principal component analysis (PCA) showed that the volatiles of different brands of sausages were significantly different (p < 0.05). The volatiles of S1 and S4 were more similar and significantly different from the other two samples (p < 0.05). Among them, there were 14 key volatile substances in the four samples, of which 3-hydroxy-2-butanone and diallyl sulfide were common to all four sausages. Combined textural and sensory evaluations revealed that smoked sausages exhibited superior characteristics in resilience, cohesiveness, springiness, gumminess, and chewiness. Additionally, smoked sausages were found to be more attractive in color, moderately spicy, and salty, while having a lower fat content. In conclusion, smoked sausages are preferred by consumers over flavored oil sausages.

Targeted inhibition of biogenic amine-producing strains by spice extracts and control of biogenic amine accumulation in reduced-salt dry sausages

This study aimed to screen spice extracts that can target the inhibition of biogenic amine (BA)-producing bacteria and reduce the BA accumulation in reduced-salt dry sausages. A total of 59 bacterial strains were isolated from reduced-salt dry sausages; among them, three isolates, namely, Staphylococcus epidermidis S1, S. saprophyticus S2, and S. edaphicus S3, had the strongest ability to produce BA. Eight spice extracts, i.e. Angelica dahurica, cinnamon, ginger, clove, fennel, Amomum, nutmeg, and orange peel, were extracted. The inhibition zone diameter and minimum inhibitory concentration indicated that A. dahurica, Amomum, and clove elicited the strongest inhibitory effect on BA-producing strains. Growth kinetics showed the strongest inhibitory effect of clove extracts, followed by Amomum and A. dahurica. In the medium system, clove extract was the most effective in controlling the total BA content by inhibiting of BA-producing strains S. epidermidis S1, S. saprophyticus S2, and S. edaphicus S3; their contents were reduced by 23.74%, 31.05% and 21.37%, respectively. In the dry sausage system, the control of BA accumulation by clove was quite prominent, and the total BA content was reduced from 373.70 mg/kg to 259.05 mg/kg on day 12.

Effect of Inoculation with Autochthonous Lactic Acid Bacteria on Flavor, Texture, and Color Formation of Dry Sausages with NaCl Partly Substituted by KCl

The effects of inoculating lactic acid bacteria (LAB), specifically Lactiplantibacillus plantarum, Latilactobacillus sakei, Latilactobacillus curvatus, and Weissella hellenica on the flavor, texture, and color formation of dry sausages in which NaCl was partially substituted by 40% KCl, were explored in this study. It was found that LAB inoculation increased the presence of ketones, alcohols, acids, esters, and terpenes. It also reduced the pH, moisture, protein, and fat content, improving the b*-value, flavor, and texture of the sausages. Notably, L. sakei inoculation showed the most significant improvement in dry sausages with NaCl substitutes, especially on the reduction of bitterness. Meanwhile, there was a close positive correlation between the LAB count with the alcohols and esters formation of dry sausage with NaCl substitution (p < 0.05). These findings offer insight into improving the product characteristics of dry sausages using NaCl substitutes.

Valorization of Dairy and Fruit/Berry Industry By-Products to Sustainable Marinades for Broilers' Wooden Breast Meat Quality Improvement

The study aims to improve the quality of wooden breast meat (WBM) via the use of newly developed marinades based on selected strains of lactic acid bacteria (LAB) in combination with the by-products of the dairy and fruit/berry industries. Six distinct marinades were produced based on milk permeate (MP) fermented with Lacticaseibacillus casei (Lc) and Liquorilactobacillus uvarum (Lu) with the addition of apple (ApBp) and blackcurrant (BcBp) processing by-products. The microbiological and acidity parameters of the fermented marinades were evaluated. The effects of marinades on the microbiological, technical, and physicochemical properties of meat were assessed following 24 and 48 h of WBM treatment. It was established that LAB viable counts in marinades were higher than 7.00 log10 colony-forming units (CFU)/mL and, after 48 h of marination, enterobacteria and molds/yeasts in WBM were absent. Marinated (24 and 48 h) WBM showed lower dry-matter and protein content, as well as water holding capacity, and exhibited higher drip loss (by 8.76%) and cooking loss (by 12.3%) in comparison with controls. After WBM treatment, biogenic amines decreased; besides, the absence of spermidine and phenylethylamine was observed in meat marinated for 48 h with a marinade prepared with Lu. Overall, this study highlights the potential advantages of the developed sustainable marinades in enhancing the safety and quality attributes of WBM.

TMT-labeled quantitative proteomic reveals the mechanism of proteolysis and taste improvement of dry-cured bacon with Staphylococcus co-inoculation

To understand the mechanism of co-inoculation of Staphylococcus xylosus and Staphylococcus vitulinus (SX & SV) on structural protein degradation and taste enhancement of dry-cured bacon, protease activities, protein degradation, surface morphology of proteins and taste parameters of dry-cured bacon with Staphylococcus inoculation were investigated. The dry-cured bacon with co-inoculation of Staphylococcus xylosus and Staphylococcus vitulinus showed the best taste attributes. High residual activities in cathepsin B + L (more than 1.6-fold) and alanyl aminopeptidase (more than 1.4-fold) accelerated structural protein degradation in SX & SV. 32 down-regulated proteins were identified in SX & SV by TMT-labeled quantitative proteomic compared with control group; myosin and actin showed the most intense response to the accumulation of sweet and umami amino acids, and atomic force microscopy confirmed structural proteins breakdown by morphological changes. The accumulation of glutamic acid, alanine and lysine was mainly responsible for taste improvement of dry-cured bacon with Staphylococcus co-inoculation.

Analysis and comparison of the quality and flavour of traditional and conventional dry sausages collected from northeast China

In this study, the physicochemical properties and flavour profile of traditional dry sausages (T-SH, T-DXAL, T-HG, T-MDJ, T-HRB) collected from various wet markets were compared with those of conventional dry sausages (C-QL, C-ND, C-YSD, C-YC, C-HRL) collected from various food companies in northeast China. Traditional dry sausages were characterised by a low moisture content, a low water activity, and a high shear force after a long fermentation time compared with conventional dry sausages. Electronic nose and electronic tongue signals combined with chemometrics methods were applied for a comprehensive qualitative analysis of the odour and taste of dry sausages. A total of 61 volatile compounds were identified using gas chromatography-mass spectrometry, and the multivariate chemometrics analysis confirmed the difference in volatile compounds between traditional and conventional samples. Moreover, the sensory evaluation revealed that conventional dry sausages lacked the characteristic fermented flavour of traditional dry sausages.

The combination of high-throughput sequencing and LC-MS/MS reveals the mechanism of Staphylococcus inoculation on bacterial community succession and taste development during the processing of dry-cured bacon

BACKGROUND

To understand the mechanism of co-inoculation of Staphylococcus vitulinus and Staphylococcus xylosus (SX&SV) on taste quality of dry-cured bacon, physicochemical parameters, microbial community, metabolite compositions and taste attributes were investigated during the processing of dry-cured bacon with Staphylococcus inoculation. The potential correlation between core bacteria and metabolites was evaluated, and the metabolic pathway of key metabolites was further explored.

RESULTS

The values of pH, water activity and adhesiveness were significantly lower in SX&SV, and more than 2.56- and 2.15-fold higher values in richness and overall acceptance were found in SX&SV bacon than in CK bacon. The overwhelming advantage of Staphylococcus was confirmed in SX&SV by high-throughput sequencing. Sixty-six metabolites were identified by liquid chromatography-tandem mass spectrometry, and oligopeptides, amino acid derivatives and organic acids were the key components. Pearson correlation demonstrated that the accumulation of oligopeptides, amino acid derivatives and organic acids were positively correlated with high abundance of Staphylococcus. The pathways of purine metabolism, glutathione metabolism and glutamate metabolism were mainly involved in developing the taste quality of SX&SV.

CONCLUSION

The co-inoculation of Staphylococcus vitulinus and Staphylococcus xylosus enhanced the taste attributes of dry-cured bacon. The present study provides the theoretical reference with respect to regulating the taste quality of fermented meat products by starter cultures of Staphylococcus during manufacture. © 2023 Society of Chemical Industry.

Analysis on driving factors of microbial community succession in Jiuyao of Shaoxing Huangjiu (Chinese yellow rice wine)

The microbial ecosystem of fermented food is greatly disturbed by human activities.Jiuyao is important saccharification starter for brewing huangjiu. The interaction between environmental factors and microorganisms significantly affected the microbial community structure at different stages of Jiuyao manufacturing. This study combined environmental factor analysis and high-throughput sequencing technology to comprehensively analyze the specific changes of microbial community and environmental factors in each fermentation stage of Jiuyao production and their correlation. The results showed that the activities of liquefaction enzyme, glycosylation enzyme and acid protease reached the highest value on the 8 th day (192 h) after the beginning of fermentation, and the cellulase activity reached the highest value at the end of fermentation. Pediococcus（37.5 %-58.2 %）, Weissella（9.2 %-27.0 %） and Pelomonas（0.1 %-12.1 %） were the main microbial genera in the genus bacteria, and Saccharomycopsis（37.1 %-52.0 %）, Rhizopus（12.5 %-31.0 %） and Saccharomyces（4.0 %-20.5 %） were the main microbial genera in the genus fungi. The results of correlation analysis showed that the microbial communities in Jiuyao were closely related to environmental factors. Most microbial communities were positively correlated with temperature, but negatively correlated with ambient humidity, CO2 concentration, acidity and water content of Jiuyao. In addition, the transcription levels of enzymes related to microbial glucose metabolism in Jiuyao were higher in the late stage of Jiuyao fermentation. Interestingly, these enzymes had high transcription levels in fungi such as Saccharomycopsis, Rhizopus and Saccharomyces, as well as in bacteria such as Pediococcus and Lactobacillus. This study provides a reference for revealing the succession rule of microbial community structure caused by environmental factors during the preparation of Jiuyao in Shaoxing Huangjiu.

Combination of ultrasound treatment and starter culture for improving the quality of beef jerky

The effects of treatment by ultrasound (US), inoculation of Pediococcus acidilactici BP2 strain (BP), and their combination (US-BP) on the quality characteristics of beef jerky were investigated during fermentation for 6 days. Moisture contents and water activity were highest after the US and US-BP treatments (P < 0.05). These effects were attributed to the decreased moisture mobility in beef jerky during ultrasonication. Meanwhile, samples treated with US and US-BP displayed more broken muscle fibers and larger gaps and cavities between the adjacent muscle bundles, resulting in lower shear force values compared to the other samples (P < 0.05), which indicated that the US and US-BP treatments improved the tenderness of beef jerky. Moreover, treatment with BP promoted the flavor development of beef jerky. The US-BP treatment improved the sensory attributes of beef jerky. In conclusion, US-BP is a promising strategy to improve the quality of beef jerky.

Effect of gamma irradiation treatment on microstructure, water mobility, flavor, sensory and quality properties of smoked chicken breast

Effect of gamma irradiation on quality, flavor and sensory properties of smoked chicken breasts were investigated. Results indicated irradiation doses >3 kGy were effective for sterilization, while also produced a significant effect on overall quality of smoked chicken breast. Irradiation treatment could inhibit protein oxidation and accelerate lipid oxidation of smoked chicken breasts. High irradiation doses could increase the instability of free and bound water, as well as increase muscle fiber gap and juice loss significantly. Irradiation treatment also promoted free fatty acids and taste-presenting nucleotides degradation, effectively increased fresh-tasting amino acids contents and decreased bitter and sweet-tasting amino acids contents. The types and relative contents of volatiles, especially aldehydes, alcohols, aromatic hydrocarbons, and phenolic compounds, also changed after irradiation, while tartaric, pyruvic, and malic acids decreased. Results obtained can provide valuable reference data for improving the quality and flavor of smoked chicken breasts using gamma irradiation technology.

Insights into the flavor perception and enhancement of sodium-reduced fermented foods: A review

Salt (sodium chloride, NaCl) is a vital ingredient in fermented foods, which affects their safety, texture, and flavor characteristics. Recently, the demand for reduced-sodium fermented foods has increased, as consumers have become more health-conscious. However, reducing sodium content in fermented foods may negatively affect flavor perception, which is a critical quality attribute of fermented foods for both the food industry and consumers. This review summarizes the role of salt in the human body and foods and its role in the flavor perception of fermented foods. Current sodium reduction strategies used in the food industry mainly include the direct stealth reduction of NaCl, substituting NaCl with other chloride salts, and structure modification of NaCl. The odor-induced saltiness enhancement, application of starter cultures, flavor enhancers, and non-thermal processing technology are potential strategies for flavor compensation of sodium-reduced fermented foods. However, reducing sodium in fermented food is challenging due to its specific role in flavor perception (e.g., promoting saltiness and volatile compound release from food matrices, inhibiting bitterness, and changing microflora structure). Therefore, multiple challenges must be addressed in order to improve the flavor of low-sodium fermented foods. Future studies should thus focus on the combination of several strategies to compensate for the deficiencies in flavor resulting from sodium reduction.

The Changes Occurring in Proteins during Processing and Storage of Fermented Meat Products and Their Regulation by Lactic Acid Bacteria

Protein, which is the main component of meat, is degraded and oxidized during meat fermentation. During fermentation, macromolecular proteins are degraded into small peptides and free amino acids, and oxidation leads to amino acid side chain modification, molecular crosslinking polymerization, and peptide chain cleavage. At different metabolic levels, these reactions may affect the protein structure and the color, tenderness, flavor, and edible value of fermented meat products. Lactic acid bacteria are currently a research hotspot for application in the fermented meat industry. Its growth metabolism and derivative metabolites formed during the fermentation of meat products regulate protein degradation and oxidation to a certain extent and improve product quality. Therefore, this paper mainly reviews the changes occurring in proteins in fermented meat products and their effects on the quality of the products. Referring to studies on the effects of lactic acid bacteria on protein degradation and oxidation from all over the world, this review aims to provide a relevant reference for improving the quality of fermented meat products.

Flavour Compensation Role of Yeast Strains in Reduced-Salt Dry Sausages: Taste and Odour Profiles

The effects of different yeast strains including Pichia kudriavzevii, Torulaspora delbrueckii, and Debaryomyces hansenii on the taste and odour profiles of reduced-salt dry sausages were explored. Inoculation of P. kudriavzevii and D. hansenii compensated for the lack of saltiness and umami tastes of reduced-salt sausages. Furthermore, inoculation of P. kudriavzevii and T. delbrueckii resulted in an odour profile in the reduced-salt dry sausages that was similar to traditional dry sausages. According to the volatile analysis, the contents of certain alcohols, acids, esters and terpenes were higher in the inoculated sausages. Finally, the sensory evaluation indicated that the inoculation of P. kudriavzevii and D. hansenii contributed positively to the aroma and saltiness of reduced-salt dry sausages. In conclusion, P. kudriavzevii and D. hansenii can be employed as effective starter cultures to compensate for the flavour deficiencies of reduced-salt dry sausages.

Combined Effect of High-Pressure Processing with Spice Extracts on Quality of Low-Salt Sausage during Refrigerated Storage

The study evaluated the combined effect of high-pressure processing (HPP) and spice extracts on low-salt sausages during refrigerated storage. Physicochemical and microbiological characteristics of the sausages were determined. HPP treatment increased the thiobarbituric acid reactive substances (TBARS) value and the carbonyl content of the samples (p < 0.05), which meant lipid and protein oxidation was accelerated. Adding clove and cinnamon extracts can retard the oxidation caused by HPP (p < 0.05). The pH of the sausages treated with both the spice extracts and HPP maintained a higher pH value during the storage (p > 0.05). Compared with the samples treated with HPP or with the spice extracts alone, the combined treatment observably inhibited the growth of spoilage bacteria (p < 0.05) and improved the microbial community. The results demonstrated that the use of clove and cinnamon extracts in conjunction with HPP improved the storage quality and prolonged the shelf-life of the low-salt sausages. Thus, the combined use of spice extracts and HPP can be developed as a promising way to preserve low-salt meat products.

Complete Replacement of Nitrite With a Lactobacillus fermentum on the Quality and Safety of Chinese Fermented Sausages

This study investigated the positive effects of complete replacement of nitrite with a Lactobacillus fermentum on the quality and safety of Chinese fermented sausages, and evaluated the risk of this strain. The effects of the strain on pH, color, nitrite, thiobarbituric acid reactive substances (TBARS), total volatile basenitrogen (TVB-N), metmyoglobin (Met-Mb), biological amines, free amino acid content, and sensory index have been studied. The results revealed that the strain reduced the pH of the sausages, which reduced the risk of food-borne pathogens, and accelerated the acidification and gelation process. The inoculation of the strain produced pink color similar to 50 mg/kg nitrite, significantly reducing the residual risk of nitrite in the sausages. In addition, the strain effectively improved quality and nutrition of the sausages through preventing fat oxidation, protein decomposition, and myoglobin oxidation and increasing free amino acid content. The harmful biogenic amines species of the treated sample were reduced, although the tyramine contents were higher than the control, and the contents of the two groups were all far below the specified limit (800 mg/kg). The sensory analysis showed that the strain enhanced the taste, flavor, sourness, and overall acceptability of the sample sausages. Therefore, replacing nitrite completely with the strain L. fermentum could be a potential strategy to produce healthier and safer acceptable sausages through decreasing the risk of nitrite and improving nutrition and quality of the sausages.