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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. [ABSTRACT FROM AUTHOR]

This study sought to assess the cholesterol-lowering activity of peptides obtained from milk casein hydrolyzed with neutrase. The bioactive peptides were separated using a Sephadex G-10 chromatographic column (Amersham Pharmacia Biotech, Uppsala, Sweden) after ultrafiltration using a 1-kDa molecular mass cutoff membrane. Via ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry, we determined that peptides Thr-Asp-Val-Glu-Asn [TDVEN; β-casein f(143–147)], Leu-Gln-Pro-Glu [LQPE; β-casein f(103–106)], Val-Ala-Pro-Phe-Pro-Glu [VAPFPE; α S1 -casein f(40–45)], and Val-Leu-Pro-Val-Pro-Gln [VLPVPQ β-casein f(185–190)] reduced micellar cholesterol solubility. After Caco-2 cells were treated with LQPE, VLPVPQ, and VAPFPE, the Niemann-Pick C1-Like 1 (NPC1L1) protein levels decreased by (means ± SEM) 19.33 ± 2.47%, 52.1 ± 3.77%, and 23.09 ± 8.52%, respectively, compared with the control group. Treatment with each peptide induced significant upregulation of ATP binding cassette subfamily G member 8 antibody (ABCG8) mRNA expression by 398.1 ± 23.27%, 86.4 ± 27.07%, and 92.8 ± 8.49%. We found that VLPVPQ and LQPE significantly upregulated ATP-binding cassette transporter A1 (ABCA1) transcription by 203.9 ± 8.44% and 220.8 ± 36.42% respectively, whereas VLPVPQ significantly decreased mRNA expression of acetyl-CoA-acetyltransferase 2 (ACAT2) and microsomal triacylglycerols (MTP). The cholesterol-lowering action of milk-derived peptides may be induced by suppression of micellar cholesterol solubility and affects the expression of cholesterol absorption–related proteins and enzymes in intestinal epithelial cells. This research discovers new milk-derived peptides with decreasing cholesterol micellar solubility and provides a theoretical basis of in vitro cholesterol-lowering effects of peptides. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of glutaraldehyde (GTA) on the structure, mechanical properties and thermal stability of gelatin films, gelatin films modified by GTA at various pH (4.5, 6.5, and 11), were prepared. According to FTIR analysis, the reaction mechanism between GTA and gelatin was different at various pH. With the addition of GTA, the intermolecular forces (hydrogen bonds and ionic bonds) and triple helix structure of gelatin film were significantly disrupted. At pH 4.5, gelatin films modified by GTA showed the highest mechanical properties and thermal stability among all films, which tensile strength and residues in TGA up to 16.13 MPa and 15.05%, respectively. Therefore, an optimum pH was around 4.5 in gelatin films cross‐linked by GTA. [ABSTRACT FROM AUTHOR]

A newly developed molecularly imprinted photonic polymer (MIPP) film, which was prepared by colloidal crystal templating and surface molecular imprinting, was used for selective capture of S-layer protein (SLP) from a complex Lactobacillus acidophilus sample. The colloidal crystal templates were formed by a dipping process followed by chemical binding of the imprinted template SLP molecules. A sandwich structure consisting of two glass slides was formed after the SLP–silica layer had been covered with a poly(methyl methacrylate) glass slide. After polymerization of the SLP–silica layer with the preprepared polymerization solution, hydrofluoric acid and acetic phosphate buffer solutions removed the silica particles and SLP molecules, respectively. The MIPP film obtained exhibited a three-dimensional, highly ordered and interconnected macroporous structure (pore size greater than 200 nm), which is specifically accessible to SLP molecules. The adsorbed SLP molecules were simply and straightforwardly detected by a fiber-optic spectrometer. The redshift of the Bragg diffraction peak of the MIPP film was linearly related to the number of SLP molecules that had been harvested in the film. The detection limit of the SLP–MMIP–fiber-optic spectrometer method for SLP was 1 ng mL-1. The MIPP sensor was successfully applied to detect SLP molecules in a crudely extracted Lactobacillus acidophilus sample. Our results prove the applicability of the SLP–MIPP film for fast and real-time measurement of SLP. [ABSTRACT FROM AUTHOR]

Stewed pork-hock in soy sauce is a representative meat product in China. Its taste quality is highly related to primary and secondary metabolites. This study researched the effects of stewing points (0, 30, 60 and 90 min) on the metabolites profile variation of stewed pork-hock in soy sauce by using 1H NMR spectroscopy with multivariate data analysis. The metabolome consisted of 25 metabolites, including amino acids, sugars, organic acids, nucleic acids and their derivatives. PC1 and PC2 explained a total of 90% and 7.8% of variables, respectively. Most amino acids, sucrose, β-glucose, acetate and creatinine increased during stewing, while creatine decreased. Fumarate kept extremely low content during the whole stewing process. The 60 and 90 min stewed points owned relatively higher levels of metabolites and sensory evaluation compared to other points. These results indicated that 1H NMR-based metabolomics is useful for a better understanding on the change of meat products during the stewing process, thus improving the stewing time to provide a better taste and higher product sales of stewed pork-hock in soy sauce. Unlabelled Image • Taste is the major factor which decided by biochemical composition. • The metabolites variation of stewed pork-hock in different stewing points. • The proportions and combinations of metabolites explained the specific taste of stewed pork-hock in soy sauce. • NMR provides detailed information on specific components of complex mixtures. [ABSTRACT FROM AUTHOR]

In this study, we aimed to investigate the effect of ultrasound (US) combined with different amounts of psyllium husk powder (PHP) (0 %, 0.5 %, 1 %, 2 %, 3 %) on the gelation and structure of goose myofibrillar protein (GMP). The analysis of circular dichroism, surface hydrophobicity and fluorescence spectroscopy showed that the combination of US and 2 % PHP could promote the development of myofibrillar protein (MP) secondary and tertiary structure, which could facilitate the exposure of active site and enhance the interaction between GMP and PHP. Meanwhile, the thermal stability was enhanced with US and PHP treatment. In addition, the analysis of rheology, Low field nuclear magnetic resonance (LF-NMR), Fourier transform infrared (FT-IR) spectroscopy and microstructure showed that US combined with 2 % PHP addition could make the gel network structure denser. Thus, these results suggested that the combination of US and 2 % PHP could promote the unfolding of GMP structure and improve its gel properties. This study provides new insights for the interaction of GMP and PHP under US treatment, improving the application of goose meat in practical production. [Display omitted] • The average particle size of goose myofibrillar protein (GMP) was decreased. • Ultrasound (US) and psyllium husk powder (PHP) improved the thermal stability of GMP. • The free water was converted into immobilized water in US/PHP-2 % group. • US/PHP-2 % gel has more uniform/denser microstructure and better gel properties. [ABSTRACT FROM AUTHOR]

Ternary nanobiocomposite films based on sodium alginate (SA) with cellulose nanocrystals (CNC) derived from shaddock peel and ε-polylysine (ε-PL) have been prepared and characterized. The tensile strength and Young's modulus of nanobiocomposite films increased from 51.18 to 67.68 MPa and from 4.8 to 7.6 GPa upon CNC loading from 0.5 to 2.5 wt %. The positive effects of the addition of CNC in SA matrix were also confirmed by reductions in water vapor permeability (WVP). SA-based nanobiocomposites showed significant antibacterial activity against Escherichia coli and Staphylococcus aureus influenced by the ε-PL content. The films exhibited homogeneous and cohesive structures, indicating strong interactions between the filler and matrix. In addition, the good dispersion of CNC in the SA matrix could increase the stability of ε-PL and promote the diffusion of the antimicrobial agent from the films. Practical Applications Chilled duck is an important raw material for making the sauce duck, roast duck, favor duck and it has a very broad consumer market. The chilled duck stability during storage can be enhanced by film-coating as a prominent technique, and therefore an nanobiocomposite film based on sodium alginate (SA) incorporation with ε-polylysine (ε-PL) and cellulose nanocrystals (CNC) derived from shaddock peel were prepared in this study. The film-coating has a good antibacterial effect on preservation of chilled duck. This study will find a successful packing method for chilled duck and improve the shelf life. [ABSTRACT FROM AUTHOR]

BACKGROUND: Goose meat is rough and embedded with dense connective tissue, impairing protein solubility. Therefore, to improve the functional properties of goose myofibrillar protein (GMP), ultrasound was used to assist the phosphorylation of GMP. RESULTS: The fact that GMP attached covalently with the phosphate group of sodium tripolyphosphate (GMP‐STP) was disclosed directly by Fourier transform infrared spectroscopy. Furthermore, ultrasound significantly improved the hydrophobicity and solubility of GMP‐STP, which could be attributed to the conversion of α‐helix to β‐sheet, β‐turns, and random coils by sonication. The spatial stabilization of the protein phosphorylation process was boosted by ultrasound, making the droplets more dispersed, and thus an improvement in the functional properties of GMP‐STP was observed. Water‐holding capacity, oil‐binding capacity, and emulsifying and foaming properties were best at an ultrasound power of 400 W. CONCLUSION: Ultrasound‐assisted phosphorylation has great potential to modulate the structure–function relationship of proteins. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Cathodic electrodeposition (CED) has received great attention in metal-organic frameworks (MOFs) synthesis due to its distinguished properties including simplicity, controllability, mild synthesis conditions, and product continuously. Here, we report the fabrication of thin (Et 3 NH) 2 Zn 3 (BDC) 4 (E-MOF-5) film coated solid phase microextraction (SPME) fiber by a one-step in situ cathodic electrodeposition strategy. Several etched stainless steel fibers were placed in parallel in order to achieve simultaneously electrochemical polymerization. The influence of different polymerization parameters Et 3 NHCl concentration and polymerization time were evaluated. The proposed method requires only 20 min for the preparation of E-MOF-5 coating. The optimum coating showed excellent thermal stability and mechanical durability with a long lifetime of more than 120 repetitions SPME operations, and also exhibited higher extraction selectivity and capacity to four estrogens than commonly-used commercial PDMS coating. The limits of detection for the estrogens were 0.17–0.56 ng mL −1 . Fiber-to-fiber reproducibility (n = 8) was in the respective ranges of 3.5%–6.1% relative standard deviation (RSD) for four estrogens for triplicate measurements at 200 ng mL −1 . Finally, the (E-MOF-5) coated fiber was evaluated for ethinylestradiol (EE2), bisphenol A (BPA), diethylstilbestrol (DES), and hexestrol (HEX) extraction in the spiked milk samples. The extraction performance of this new coating was satisfied enough for repeatable use without obvious decline. [ABSTRACT FROM AUTHOR]

Peptidoglycan ( PG) is available from a wide variety of lactic acid bacteria ( LAB) and is the main structure of cell wall components. Phosphorylated modification would bring new properties such as the potential antioxidant activities and antiviral capability to an organic molecule. In the present work, small molecular fragments of PG (derived from Lactobacillus acidophilus) hydrolysed by mutanolysin were phosphorylated under optimal conditions. P- PG had a monomer molecular structure of Glc NAC[ PO3]-Mur NAC-Ala-Glu-Lys-Ala, with a molecular mass of 884 Da and a phosphorus content of 8.9%. P- PG displayed some immunoregulatory activity in lipopolysaccharides ( LPS) stimulated RAW 264.7 macrophages. Compared with the LPS-stimulated group, the addition of P- PG inhibited the secretion of GM- CSF, TNF-α and IL-1 in a dose-dependent manner. The effect of 50 μg mL−1 of P- PG was more significant than 50 μg mL−1 of PG. Lower fluorescence of lysosomes was observed in P- PG-treated RAW 264.7 cells may also reveal some immune defence function in the LPS-induced macrophages. [ABSTRACT FROM AUTHOR]

We describe an aptamer-based colorimetric assay for chloramphenicol (CAP) based on the ability of anti-single-stranded DNA antibody (anti-ssDNA Ab) to recognize ssDNA, and the catalytic ability of PowerVision (PV), which is a polymeric conjugate of horseradish peroxidase and antibody with a high enzyme-to-antibody ratio. The complementary DNA of the aptamer (cDNA) was immobilized on magnetic gold nanoparticles (FeO@Au) and used as a capture probe (AuMNPs-cDNA). The ssDNA Ab and PV were conjugated to AuNPs to form signal tags that recognize ssDNA with anti-ssDNA Ab to form beads containing the amplified probe (AuMNPs-cDNA@anti-ssDNA Ab/PV-AuNPs). The PV on their surface catalyzes the oxidation of the substrate 3,3',5,5'-tetramethylbenzidine to produce a color change which is quantified by absorptiometry at 652 nm. The assay has a linear calibration plot for CAP in the 0.01 to 100 ng mL range, with a detection limit as low as 3 pg mL. The method was successfully employed to detect CAP in real samples. Results were consistent with data obtained using a conventional enzyme-linked immunosorbent assay. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Lactobacillus species are potential probiotic bacteria for humans because of their capacity to improve certain biological functions in the host's immune system. In this study, we focused on three peptidoglycans (PGNs) derived from different Lactobacillus strains and investigated each PGN's anti-inflammatory capacity. Each PGN was analyzed using HPLC, MALDI–TOF/TOF MS and FTIR. All three PGNs displayed a β-1,4-linked N -acetylmuramic acid (MurNAc) and N -acetylglucosamine (GlcNAc) structure with some modifications in the polypeptides at the end of the MurNAc residue. In a new insight, we found that PGNs inhibit the release of inflammatory cytokines in LPS-induced RAW 264.7 cells; a capacity that may be related to the TLR-4 pathway. The goal for exploring PGN diversity in Lactobacillus strains is to better understand the potential use of Lactobacillus PGNs in food and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: The traditional screening method for umami peptide, extracted from porcine bone, was labor‐intensive and time‐consuming. In this study, the rapid screening method and molecular mechanism of umami peptide was investigated. RESULTS: This article showed that a more precisely rapid screening method with composite machine learning and molecular docking was used to screen the potential umami peptide from porcine bone. As reference, 24 reported umami peptides were predicated by composite machine learning, with the accuracy of 86.7%. In this study, potential umami peptide sequences from porcine bone were screened by UMPred‐FRL, Umami‐MRNN Demo, and molecular docking was used to provide further screening. Finally, nine peptides were screened and verified as umami peptides by this method: LREY, HEAL, LAKVH, FQKVVA, HVKELE, AEVKKAP, EAVEKPQS, KALSEEL and KKMFETES. The hydrogen bonding was deemed to be the main interaction force with receptor T1R3, and domain binding sites were Ser146, His121 and Glu277. The result demonstrated the feasibility of machine learning assisted T1R1/T1R3 receptor for rapid screening umami peptides. The screening method would not only adapt to screen umami peptides from porcine bone but possibly applied for other sources. It also provided a reference for rapid screening of umami peptides. CONCLUSION: The manuscript lays a rapid screening method in screening umami peptide, and nine umami peptides from porcine bone were screened and identified. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND Diacetyl (2,3-butanedione) is a common flavor aroma from fermented dairy products. There is a need to screen new microorganisms that can efficiently produce large amounts of diacetyl. RESULTS A new lactic acid bacterium that produced high concentrations of diacetyl was identified based on Gram staining, microscopic examination and 16S rDNA sequence analysis as Lactococcus lactis DX. Its α-acetolactate decarboxylase ( ALDC) was purified using 0.45 g mL−1 ammonium sulfate precipitation, Sephacryl S-300 and S-200 HR and native- PAGE. The purified ALDC displayed a monomer structure and had a molecular mass of about 73.1 kDa, which was estimated using SDS-PAGE. IR analysis showed that the ALDC had a typical protein structure. The optimal temperature and pH for ALDC activity were 40 °C and 6.5 respectively. The ALDC of L. lactis DX was activated by Fe2+, Zn2+, Mg2+, Ba2+ and Ca2+, while Cu2+ significantly inhibited ALDC activity. Leucine, valine and isoleucine activated the ALDC. CONCLUSION A strain that had high ability to produce diacetyl was identified as L. lactis DX. The difference in diacetyl production may be due to the ALDC, which is different from other ALDCs. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

An enzyme-amplified magnetic immunosensor was developed for the sensitive and selective detection of ractopamine (RAC) in fodder using a quartz crystal microbalance (QCM). Magnetic capture probes were prepared by immobilizing β-cyclodextrins (β-CD) on Fe 3 O 4 nanoparticles in order to enrich RAC. PowerVision (PV), a kind of enzyme–polymer complex with a high enzyme-to-antibody ratio, served as a signal label. Horseradish peroxidase (HRP) on the immnunocomplex, which arises from sandwich-type immunoreactions, causes 3,3′,5,5′-tetramethylbenzidine (TMB) to produce large amounts of sedimentation with a mass proportional to RAC. The large amounts of HRP on the PV greatly amplify the QCM sensor's signal. Under optimum conditions, the differences of the QCM frequency (Δ f ) are proportional to the concentration of RAC over the range from 0.03 to 25 ng mL −1 . The limit of detection was 0.01 ng mL −1 . More importantly, this assay's results in swine fodder samples were consistent with those of ELISA, with recoveries between 92.3% and 110%. Due to its high sensitivity, portability and selectivity, the immunosensor achieved reliable quantification of RAC in real fodder samples and has the potential to become an on-site screening tool to enhance food safety. [ABSTRACT FROM AUTHOR]

Exopolysaccharide (EPS) was isolated and purified fromLactococcus lactissubsp.Lactisculture and then selenium chloride oxide (SeCl2O) was added to synthesise selenium-exopolysaccharide (Se-EPS). This study sought to evaluate the immunomodulatory effects of EPS and Se-EPS on the activity of peritoneal macrophages and spleen lymphocytes. In mouse peritoneal macrophages, the EPS and Se-EPS enhanced phagocytosis and increased nitric oxide (NO), IFN-γ, IL-1, IL-6 and IL-12 secretion, but not IL-10 levels. Preliminaryin vitrotests revealed that EPS and Se-EPS stimulated mouse spleen lymphocyte proliferation, and strongly improved levels of TNF-α, IL-2 and IL-6 mRNA in spleen cells. These findings indicate that EPS and Se-EPS can enhance the immune response via enhanced macrophage and spleen lymphocyte stimulation. Se-EPS showed stronger immunomodulatory activity than EPS. [ABSTRACT FROM PUBLISHER]

In this research, the graphene with excellent dispersity is prepared successfully by introducing gold nanoparticle to separate the individual sheets. Various techniques are adopted to characterize the prepared graphene and graphene-gold nanoparticle composite materials. This fabricated new composite material is used as the support material to construct a novel tyrosinase based biosensor for detection of bisphenol A (BPA). The electrochemical performances of the proposed new enzyme biosensor were investigated by differential pulse voltammetry (DPV) method. The proposed biosensor exhibited excellent performance for BPA determination with a wide linear range (2.5 × 10 −3 –3.0 μM), a highly reproducible response (RSD of 2.7%), low interferences and long-term stability. And more importantly, the calculated detection limit of the proposed biosensor was as low as 1 nM. Compared with other detection methods, this graphene-gold nanoparticle composite based tyrosinase biosensor is proved to be a promising and reliable tool for rapid detection of BPA for on-site analysis of emergency BPA related pollution affairs. [ABSTRACT FROM AUTHOR]

Optimisation of enzymatic hydrolysis of β-casein with cell envelope proteinase ( CEP) from Lactobacillus acidophilus JQ-1 to produce the angiotensin-I-converting enzyme ( ACE) inhibitory peptides using response surface methodology ( RSM). Under optimal conditions (enzyme-to-substrate ([E]/[S]) ratio (w/w) of 0.132 and pH of 8.00 at 38.8 °C), the ACE inhibitory activity of hydrolysates was 72.06% and the total peptides was 11.75 mg mL−1. Scanning electron microscopy ( SEM) micrographs indicated that the tightness of the β-casein surface structure was gradually weakened and small holes appeared after enzymatic treatment, while Fourier transform infrared spectroscopy ( FTIR) spectra indicated remarkable changes in the chemical composition and macromolecular conformation of β-casein after enzymatic hydrolysis. Differential scanning calorimetry ( DSC) analysis indicated that the corresponding hydrolysates had higher thermal stability. The enzymatic hydrolysis also led to an increase in the free sulfhydryl content of β-casein hydrolysates compared with raw β-casein, which led to the increase in the antioxidant activity of β-casein hydrolysates. [ABSTRACT FROM AUTHOR]

Flavonoids are easily destroyed and their activity lost during gastrointestinal digestion. Protein-based nanocomplexes, a delivery system that promotes nutrient stability and bioactivity, have received increasing attention in recent years. This study investigated the stability, inhibitory activity against α-glucosidase and interaction mechanisms of protein-based nanocomplexes combining whey protein isolate (WPI), soybean protein isolate (SPI) and bovine serum albumin (BSA) with flavonoids (F) from A. keiskei using spectrophotometry, fluorescence spectra and molecular docking approaches. The results show that the flavonoid content of WPI-F (23.17 ± 0.86 mg/g) was higher than those of SPI-F (19.41 ± 0.56 mg/g) and BSA-F (20.15 ± 0.62 mg/g) after simulated digestion in vitro. Furthermore, the inhibition rate of WPI-F (23.63 ± 0.02%) against α-glucosidase was also better than those of SPI-F (18.56 ± 0.02%) and BSA-F (21.62 ± 0.02%). The inhibition rate of WPI-F increased to nearly double that of F alone (12.43 ± 0.02%) (p < 0.05). Molecular docking results indicated that the protein-flavonoids (P-F) binding occurs primarily through hydrophobic forces, hydrogen bonds and ionic bonds. Thermodynamic analysis (ΔH > 0, ΔS > 0) indicated that the P-F interactions are predominantly hydrophobic forces. In addition, the absolute value of ΔG for WPI-F is greater (−30.22 ± 2.69 kJ mol−1), indicating that WPI-F releases more heat energy when synthesized and is more conducive to combination. This paper serves as a valuable reference for the stability and bioactivity of flavonoids from A. keiskei. [ABSTRACT FROM AUTHOR]

Highlights: [•] The small molecule metabolites of duck meat were systematically studied by NMR. [•] Flavour composition and metabolic differences associated with age were examined. [•] The relationship of meat quality with duck age was explained. [ABSTRACT FROM AUTHOR]

Abstract: Exopolysaccharide (EPS) of Lactococcus lactis subsp. lactis was isolated and purified from MRS culture broth. Phosphorylated exopolysaccharide (P-EPS) was synthesized by using the purified EPS and sodium hexametaphosphate (SHMP). The in vitro and in vivo antioxidant activity of EPS and P-EPS was analyzed. Both EPS and P-EPS displayed superoxide anion (O2− ), hydroxyl radical (OH ) and DPPH scavenging activity. Catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity increased in serum and the livers of mice treated with EPS and P-EPS, while malondialdehyde (MDA) levels decreased. P-EPS was shown to prevent the progression of d-galactose-induced oxidative stress in hepatocytes in vivo. P-EPS showed stronger in vitro and in vivo antioxidant activity than EPS. [Copyright &y& Elsevier]

In this study, whey protein was hydrolyzed by trypsin. A calcium binding peptide was isolated and purified by ultra-filtration, gel filtration chromatography, and reverse phase HPLC from the hydrolysate. The target peptide, with a molecular weight of 555.54 Da and with the amino acid sequence Ser-Thr-Glu-Tyr-Gly, corresponds to the 48 to 52 th amino acid sequence of bovine α-lactalbumin, which exhibited a significant effect on promoting the absorption of calcium in mice. The peptide could be used as a food additive to prevent calcium deficiency in humans. [ABSTRACT FROM PUBLISHER]

Abstract: Consumers focus on tenderness and flavor when eating goose meat. This study was conducted to determine the mechanism by which goose muscle becomes tender. Changes in reactive oxygen species (ROS) and myofibril proteins (titin, nebulin, desmin, troponin-T, and β-actin) were analyzed, and the main activated proteins' (caspase-3 and caspase-9) expression levels were examined using western blot analysis. Caspase activity was compared and analyzed across different storage times using a substrate method. Significant variations in troponin-T (approximate 35kDa) and β-actin were detected between samples suspended in 10mmol/l hydrogen peroxide (H2O2) and N-acetyl cysteine (NAC) for various time periods. The data demonstrated that as goose muscle matured there were changes in proteins (titin, nebulin, desmin, troponin-T, and β-actin) and the activated fragments of caspase-3 and caspase-9, with their activities showing a significant negative correlation (P<0.05). The mean fluorescence intensity of dichlorofluorescein (DCF) in the control group was lower than the disposed groups treated with 10mmol/l H2O2, and goose meat aged 2days showed higher dihydroethidium (DHE) levels than that shown by the 0d samples. [Copyright &y& Elsevier]

Abstract: Exopolysaccharide (EPS) was isolated and purified from Lactococcus lactis subsp. Lactis culture broth. Selenium chloride oxide (SeCl2O) was added to the EPS to synthesize selenium-exopolysaccharide (Se-EPS). The in vitro and in vivo antioxidant and in vivo immunomodulatory activity of EPS and Se-EPS were compared. EPS and Se-EPS scavenged superoxide anions and hydroxyl radicals. They also increased catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, while decreasing malondialdehyde (MDA) levels in serum and in the livers of mice. Se-EPS showed stronger in vitro and in vivo antioxidant activity than were shown by EPS. The in vivo immunoenhancement activity of EPS and Se-EPS induced by cyclophosphamide (CY) treatment in immunosuppressed mice was researched. EPS and Se-EPS treatments increased macrophage phagocytosis, spleen and thymus indices and haemolytic complement activity (HC50). Se-EPS showed stronger immunomodulatory activity than did EPS. [Copyright &y& Elsevier]

Background Hypertension is a major and common threat to the health of individuals around the world. Although agents such as captopril have been shown to regulate high blood pressure effectively, they bring unfavourable side effects such as dry cough and angioedema. If angiotensin I-converting enzyme ( ACE) inhibitors derived from natural substances such as milk proteins can be shown to be safe and efficient at managing hypertension, such inhibitors will be a valuable auxiliary to agents such as captopril. Results Low-molecular-weight casein-derived peptides hydrolysed by cell envelope proteinase of Lactobacillus casei subsp. casei ( ATCC 15008) showed quite high ACE-inhibitory activity. The peptide fraction from α-casein with molecular weight between 5 and 10 kDa showed the highest ACE-inhibitory activity of 82.35%, with a 50% inhibition concentration ( IC50) of 2.36 mg mL−1. Peptides from β-casein exhibited lower ACE-inhibitory activity (56.67%, IC50 4.00 mg mL−1). Three distinct peptide sequences derived from α-casein ( αs1-cn f95-105, f106-115 and f148-166) were identified using two-dimensional gel electrophoresis coupled with matrix-assisted laser desorption/ionisation time-of-flight tandem mass spectrometry. Conclusion This work investigated the ACE-inhibitory properties of casein-derived peptides. Three distinct peptide sequences derived from α-casein were identified. Characterisation of such peptides furthers the investigation of casein-derived ACE-inhibitory peptides from fermented dairy products. [ABSTRACT FROM AUTHOR]

Abstract: Chicken breast protein was hydrolyzed by papain under optimal conditions. The antioxidant activity of the chicken breast protein hydrolysate was then evaluated in vitro and in vivo using different measurements, including reducing power and DPPH radical scavenging assays. The reducing power of the hydrolysate was 0.5 at 2.37mg/mL. The DPPH radical scavenging assay showed that the EC50 value of the hydrolysate was 1.28mg/mL. In antioxidant assays in vivo, d-galactose-induced aging mice administrated the fraction peptides of chicken breast protein hydrolysate showed significantly increased antioxidant enzyme activities, while malondialdehyde levels decreased both in serums and livers. Under a transmission electron microscope (TEM), the ultramicrostructure of hepatic tissue was observed and we found that the hydrolysate may play a part in inhibiting oxidative stress in hepatocytes in vivo. Therefore, we concluded that chicken breast protein hydrolysate exhibits significant antioxidant activity. [Copyright &y& Elsevier]

Abstract: This study sought to purify and identify a novel angiotensin I-converting enzyme (ACE) inhibitory peptide from whey protein hydrolysed by trypsin. The peptide’s amino acid sequence, as well as the molecular mechanism of the interactions between the peptide and the ACE, were also studied. Using ultrafiltration, the hydrolysate was separated into three fractions. The fraction with molecular weight of <6kDa had the greatest ACE inhibitory activity and was further separated by size exclusion chromatography on Sephadex G-25 and G-10 columns. Reverse-phase high performance liquid chromatography (RP-HPLC) was used to separate the most active fraction. The amino acid sequence of the peptide with the greatest ACE inhibitory characteristics was confirmed as Leu–Leu (LL). The molecular mechanisms, position, type, and energy of the LL/ACE interaction were investigated by using flexible molecule docking technology. [Copyright &y& Elsevier]

Summary Calcium chloride (CaCl2) and phosphates are important additives to improve product quality during meat processing. Response surface methodology was used to study the influence of CaCl2 and phosphates on the hardness, water-holding capacity (WHC) and ultra-structure of salt-soluble goose meat protein gels. The results show that the hardness and WHC of salt-soluble protein gels increased significantly when CaCl2 concentration was increased and phosphates were added. Scanning electron microscopy showed that tetrasodium pyrophosphate (TSPP) and sodium tripolyphosphate (STPP) had a greater impact on the cross-linking and pore diameter of the gel networks than sodium hexametaphosphate (SHMP). At the 0.02 m and 4:3:2 of CaCl2 concentration and the ratio of TSPP, SHMP and STPP, hardness and WHC values were 114.55 gf and 96.65%, which corresponded to the prediction value of our model. Further results showed that the hardness and WHC of gels reached the maximum with 0.3% of phosphates levels. [ABSTRACT FROM AUTHOR]

ABSTRACT Milk proteins were hydrolyzed with chymotrypsin and trypsin. Effects of hydrolysis conditions were studied through L9 (34) orthogonal experiment, and optimization hydrolysis conditions (substrate concentration, 25% (w/v); hydrolysis temperature, 45C; hydrolysis pH, 8.0; hydrolysis time, 2 h) were obtained. Six peptide fractions were separated from hydrolyzates by ultra-filtration and sephadex G-15 gel filtration chromatography. Anti-fatigue activity (swimming endurance tests) of each fraction was determined. Fraction 3 (F3) possessed longest swimming time. The anti-fatigue activity of the F3 peptide was evaluated. Loaded swimming time, serum blood urea nitrogen (SBUN), blood lactic acid and hepatic glycogen of mice were determined. F3 peptide can significantly increase the loaded swimming time and hepatic glycogen of mice, and decrease SBUN and blood lactic acid after swimming of mice. The antioxidant activity of the F3 peptide was also evaluated. F3 peptide had capacity to scavenge hydroxyl radical and superoxide anion radical. PRACTICAL APPLICATIONS Milk protein has been widely used as a material for peptides production by enzymatic hydrolysis. However, few anti-fatigue peptides from milk protein were reported. This work was found that the peptides hydrolyzed from milk protein had both anti-fatigue and antioxidant activities. It is to be expected that milk protein-derived anti-fatigue and antioxidant activity peptides would have no undesirable side-effects. As a consequence, the milk protein hydrolyzates with anti-fatigue and antioxidant activity could be applied in functional foods or beverages designed for persons suffering from diseases caused by fatigue, reactive oxygen species (ROS) and free radicals. [ABSTRACT FROM AUTHOR]

Abstract: The ability of milk protein derived Ile-Pro-Ala (IPA), Phe-Pro (FP) and Gly-Lys-Pro (GKP) peptides to inhibit angiotensin I-converting enzyme (ACE), a protein with an important role in blood-pressure regulation, were verified in vitro and in vivo. This work elucidates the modes and molecular mechanisms of the interaction of IPA, FP and GKP with ACE, including mechanisms that bind the peptides to the cofactor Zn2+. It was observed that the best docking poses obtained for IPA, FP and GKP were at the ACE catalytic site with very similar modes of interaction, including the interaction with Zn2+. The interactions, including H-bonds, hydrophobic, hydrophilic, and electrostatic interactions, as well as the interaction with Zn2+, were responsible for the binding between the bioactive peptides and ACE. [Copyright &y& Elsevier]

Abstract: The effect of fermentation conditions on the production of angiotensin-I converting enzyme (ACE) inhibitory peptide in sour milk fermented by Lactobacillus helveticus LB10 was investigated using response-surface methodology. Optimal conditions to produce the maximum production of ACE-inhibitory peptides were found to be 4% (v/w) inoculum, 7.5 initial pH of medium and 39.0°C. The fermented milk resulted in 75.46% inhibition in ACE activity. The cell-envelope proteinase, assisted by X-prolyldipeptidyl aminopeptidase of Lb. helveticus LB10 produced the ACE-inhibitory peptides. A novel ACE-inhibitory peptide from whey protein hydrolysate produced by crude proteinases of Lb. helveticus LB10 was purified. The separations were performed with Sephadex® G-75 and Sephadex G-15 gel filtration chromatography and reversed-phase, high-performance liquid chromatography. The peptide with the RLSFNP sequence was isolated from β-lactoglobulin hydrolysate and its IC50 while inhibiting ACE activity was 177.39μm. [Copyright &y& Elsevier]

Abstract: A novel exopolysaccharide (EPS) was obtained by ultra-filtration, ion exchange and sizing chromatography from a culture of Lactococcus lactis subsp. lactis 12. The EPS was mainly composed of fructose and rhamnose with a mean molecular weight of 6.9×105 Da. The EPS and its antioxidant properties were evaluated in vitro and in vivo. The EPS displayed strong antioxidant effects, exhibited the ability to scavenge hydroxyl and superoxide anion radicals, and significantly decreased the level of malondialdehyde (MDA), even while increasing the activity of catalase (CAT) and superoxide dismutase (SOD) in mice in a dose-dependent manner. The results suggest that the EPS has direct and potent antioxidant properties. [Copyright &y& Elsevier]

Abstract: In the present research, the effect of process conditions on the angiotensin-I converting enzyme (ACE) inhibitory activity of whey protein concentrate hydrolysed with crude proteinases preparation from L. helveticus LB13 was investigated systematically using response surface methodology. It was shown that ACE inhibitory activity of the whey hydrolysates could be controlled by regulation of three process conditions (hydrolysis temperature, pH and enzyme to substrate (E/S) ratio). Hydrolysis conditions for optimal ACE inhibition were defined using a response surface model. E/S ratio at 0.60, pH at 9.18 and temperature at 38.9°C were found to be the optimal conditions to obtain high ACE inhibitory activity close to 92.2% and DH of the whey protein was 18.8%. [Copyright &y& Elsevier]

Abstract: The cell-envelope proteinase (CEP) of Lactococcus lactis ssp. lactis LB12 was released from cells by treatment with lysozyme, purified by ammonium sulfate precipitation and chromatographed on DEAE-Sephadex A-25 and Sephacryl S-300 HR. The purified CEP is a monomer structure and has molecular mass of about 53kDa. Optimal activity occurred at pH 7.5 and 40°C. It is a metallopeptidase, activated by Mn2+, Mg2+, Ca2+, inhibited by Co2+, Zn2+, Ni2+ and EDTA, and a serine proteinase which is inhibited by PMSF. The sequence of the first 13 amino acids of the N-terminal of the CEP was determined to be Asp-Val-Phe-Ala-Pro-His-Met-Ala-Asn-Val-Ala-Ala-Val, and the whey protein hydrolysate produced by the CEP displayed ACE-inhibitory activity. [Copyright &y& Elsevier]

[Display omitted] • Succinylated site of chicken liver protein (CLP) is located at ε-NH 2 of lysine. • Succinylation condition design is used for modifying CLP structure and function. • Succinylation depends on the rate of pH-dependent nucleophilic attack. • Succinylation and alkalization increased the net negative charge of CLP. • Succinylation significantly improved the emulsifying properties of CLP. This work aims at investigating the pH-regulated relationship between the structural features and emulsifying properties of chicken liver protein (CLP) during succinylation and related mechanisms behind. The results demonstrated that the major succinylation sites occurred at lysine, histidine and tyrosine of CLP, and the succinylation degree increased by 30.66% as pH increased to 10. The succinylation pH elevation increased the solubility and oil absorption capacity of CLP, thus favoring its improvement in emulsifying properties, due to the succinylation process-induced increase in surface charge density and amphiphilic balance as well as modified network structure. However, the surface hydrophobicity of succinylated products decreased by 10.75% when the pH increased from 7 to 10. Besides, succinylation-induced variations in electrostatic repulsive and particle size distribution greatly improved the storability of the emulsions. These results suggested the great potential of pH-modulated succinylation to regulate the structure–property relationship of protein-based products. [ABSTRACT FROM AUTHOR]

Abstract: In the present experiments, the proteinase, aminopeptidase and x-prolyl-dipeptidyl aminopeptidase activitives were measured at 513±11.9, 376±9.3 and 23.6±1.6 units per gramme of cell-free extract of Lactobacillus helveticus JCM1004. ACE-inhibitory activity of skimmed milk hydrolysate produced by cell-free extract of L. helveticus JCM1004 was determined, and the optimum pH and hydrolysis time for the production of ACE-inhibition substances from skimmed milk were 6.5–7.0 and 6–10 h, respectively. Peptides of Val-Pro-Pro and Ile-Pro-Pro with potent ACE inhibitor and antihypertensive activitives were purified from the hydrolysate by three step-reverse-phase high-performance liquid chromatography. The IC50 values of Val-Pro-Pro and Ile-Pro-Pro were 9.13±0.21 and 5.15±0.17 μM, respectively. Significant decrease (p<0.01) in SBP of SHR was measured after a single gastric intubation of Val-Pro-Pro or Ile-Pro-Pro at 8 or 4 h, respectively. [Copyright &y& Elsevier]

An aminopeptidase was purified to homogeneity from a cell-free extract of Lactobacillus helveticus JCM 1004 by ammonium sulfate precipitation and chromatography on DEAE–Sepharose, Sephacryl S-300 HR, HiLoad 26/60 Superdex 200pg and Mono-Q 10/10. The purified aminopeptidase had a trimeric structure and a molecular mass of ∼129 kDa. The enzyme was optimally active at pH 7.0 and 40 °C. The enzyme was a metallopeptidase, strongly activated by Co2+ and inhibited by Zn2+, Cu2+, Ni2+, Fe2+ and EDTA. The enzyme showed high activity toward p-nitroanilide derivatives (pNA) of amino acids and a peptide, dipeptides and tripeptides that had hydrophobic amino acids (Leu, Ala and Phe) or diaminocarboxylic acids (Lys and Arg) at the N-termini but not p-nitroanilide derivatives or peptides with proline at their N-termini or C-termini, such as Pro–pNA, Gly–Pro–pNA, Pro–Leu and Ala–Pro. [Copyright &y& Elsevier]

The functional activity of umami peptides after digestion is poorly known. We studied the dipeptidyl peptidase-4 (DPP- IV) and angiotensin I-converting enzyme (ACE) inhibition activity of 14 umami peptides from Ruditapes philippinarum in vivo and in vitro. GRVSNCAA (IC 50 = 57.93 μmol/L) and TYLPVH (IC 50 = 1.37 μmol/L) exhibited noncompetitive ACE inhibitory activity in vitro , and GPAGPAGPR showed DPP-IV inhibitory activity (IC 50 = 160.5 μmol/L). The peptides also decreased systolic blood pressure and reduced the blood sugar level in the oral glucose tolerance test and the single blood pressure test. To understand the hypoglycemic and hypotensive mechanism of peptides, we conducted cell experiments with HepG2 and human umbilical vein endothelial cells. GRVSNCAA and TYLPVH significantly (p < 0.01) promoted nitric oxide secretion and reduced endothelin-1 production. GPAGPAGPR exerted hypoglycemic activity by increasing the content of hexokinase and pyruvate kinase.These results suggest that some umami peptides have the potential to provide human health benefits. • The functional activity of 14 umami peptides after digestion was studied. • Umami peptide GRVSNCAA and TYLPVH had ACE inhibitory activity in vitro and in vivo. • Umami peptide GPAGPAGPR showed DPP-Ⅳ inhibitory activity in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Summary: To investigate the mechanism of Penicillium inoculation on the flavour improvement of Jinhua ham, the microbial succession, free amino acid contents, volatile compound evolutions, sensory attributes and the relationship between key volatiles and sensory properties were investigated during the processing of Jinhua ham with P. aethiopicum (PA) or P. chrysogenum (PC) inoculation. The total counts of fungal communities in CK, PA and PC groups significantly increased from 2.74 log CFU*g−1 of raw ham to 5.18, 5.39 and 5.50 log CFU*g−1 from day 0 to day 28, and then decreased by 2.06, 1.94 and 1.86 log CFU*g−1 from day 28 to the final products (P < 0.001). The total contents of free amino acids significantly increased from 1584.22 mg/100 g of CK to 2117.20 mg/100 g of PA and 2174.05 mg/100 g of PC (P < 0.01); the contents of alanine, glutamic acid, lysine, valine, leucine and phenylalanine in PC were significantly higher than those of CK and PA (P < 0.05). Sensory scores of meaty aroma, nutty aroma and overall acceptance showed the largest values in PC among three groups. GC–MS results indicated that aromatic aldehydes and pyrazines in PC showed the largest increase, compared with CK and PA groups. PLS‐DA and correlation analysis demonstrated that benzaldehyde, benzeneacetaldehyde and 2,5‐dimethyl pyrazine contributed to the improvement of aroma attributes of Jinhua ham with Penicillium inoculation. The KEGG analysis further revealed that the metabolism of valine and phenylalanine was mainly involved in developing aromatic aldehydes and pyrazines of Jinhua ham with Penicillium inoculation. These results indicated that the inoculation of Penicillium could enhance the flavour quality of Jinhua ham. [ABSTRACT FROM AUTHOR]

BACKGROUND: Amino acids (AAs) are the building blocks of proteins, but they also serve as biological compounds in biochemical processes, and d‐AA isomers are increasingly being recognized as important signaling molecules. As the main organic substrate used by cells in the intestinal tract, the role of the chiral specificity of glutamine is still largely ignored. RESULTS: In a previous study, we found that d‐glutamine affected the quorum sensing of Lactiplantibacillus plantarum A3, promoted the release of signaling molecule AI‐2 and up‐regulated the expression of the LuxS gene. The results showed that when d‐glutamine and L. plantarum A3 were simultaneously applied to a mouse model, the diversity and abundance of intestinal flora in both male and female mice were increased. Interestingly, the simultaneous effect of d‐glutamine and L. plantarum A3 on the bacterial diversity and abundance of male mice was significantly higher than that of female mice. In addition, the combination of d‐glutamine and L. plantarum A3 can improve the host microecology by enhancing the population of Firmicutes such as Lactobacillus and Lachnospiraceae, reducing the population of Fusobacterium and Bacteroides and affecting metabolic pathways such as AA metabolism and transporter transport. CONCLUSION: d‐Glutamine, as a signaling molecule, can better stimulate the endogenous d‐glutamine synthesis in mice and be utilized by L. plantarum A3. Furthermore, sex differences in the changes of intestinal microflora are also found in this research. This research sheds some light on the adoption of d‐AAs combined with lactic acid bacteria in intestinal tract health treatment. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The number of patients with inflammatory bowel disease (IBD) is increasing worldwide. Since IBD is a chronic disease that seriously affects patients' life quality, preventing and alleviating IBD with natural and less side effect substances has become a research hotspot. Food‐derived bioactive peptides have been an attractive research focus due to their high efficiency and low toxicity. This paper comprehensively summarizes food‐derived peptides with intestinal health effects, focusing on peptide sequences with IBD‐regulatory effects and emphasizing the effects of their structure and physicochemical properties such as peptide length, amino acid composition, and net charge on their function. We also analyzed its regulatory mechanisms, mainly in 5 aspects: modulating the intestinal microbiota, decreasing intestinal epithelial permeability, increasing antioxidant ability, regulating the expression of inflammatory cytokines, and targeting signaling pathways. This review will help establish novel, efficient screening methods for IBD‐regulatory peptides and contribute to further research and discovery of them. [ABSTRACT FROM AUTHOR]

This study aims to identify lactic acid bacteria (LAB) isolates possessing physiological characteristics suitable for use as probiotics in yogurt fermentation. Following acid and bile salt tolerance tests, Lactiplantibacillus plantarum (NUC08 and NUC101), Lacticaseibacillus rhamnosus (NUC55 and NUC201), and Lacticaseibacillus paracasei (NUC159, NUC216, and NUC351) were shortlisted based on intraspecies distribution for further evaluation. Their physiological probiotic properties, including transit tolerance, adhesion, autoaggregation, surface hydrophobicity, biofilm formation, and antibacterial activity, were assessed. Principal component analysis indicated that Lactiplantibacillus plantarum NUC08 was the preferred choice among the evaluated strains. Subsequent investigations revealed that co-culturing Lactiplantibacillus plantarum NUC08 with 2 yogurt starter strains resulted in a cooperative and synergistic effect, enhancing the growth of mixed strains and increasing their tolerance to simulated gastric and intestinal conditions. Additionally, when Vibrio harveyi bioluminescent reporter strain was used, the 3 cocultured strains cooperated to induce the activity of a quorum sensing (QS) molecule autoinducer-2 (AI-2), hinting a potential connection between phenotypic traits and QS in the cocultured strains. Importantly, LAB viable counts were significantly higher in yogurt co-fermented with Lactiplantibacillus plantarum NUC08, consistently throughout the storage period. In conclusion, the study demonstrates that the probiotic strain Lactiplantibacillus plantarum NUC08 can be employed in synergy with yogurt starter strains, affirming its potential for use in the development of functional fermented dairy products. [ABSTRACT FROM AUTHOR]

In order to explore effective measures to control the microbes responsible for the spoilage in Jinhua ham, spoiled ham was sampled and used to characterize bacterial strains; NaCl tolerance and ability to produce biogenic amines of bacteria strains were further determined. Total of 80 strains were isolated from spoiled ham, which 6 strains and 18 strains were identified at family level and species level, respectively; C. farmei CDC 2991–81 , B. cereus ATCC 14579 and E. faecalis ATCC 19433 were main spoilage microorganisms of Jinhua ham. E. faecalis ATCC 19433 and E. faecium DSM 20477 showed higher NaCl resistance and production capacity of 2-phenylethylamine and tyramine, compared with other bacterial strains. The main producers of putrescine were strains of C. farmei CDC 2991–81 and B. cereus ATCC 14579. Nisin, sodium diacetate, citric acid, potassium lactate and potassium sorbate were active against the tested strains but at high levels. Antimicrobial interactions between binary mixtures showed that the combination of nisin and sodium diacetate had the best preservative effect on above bacteria based on the changes of fractional inhibitory concentrations index. These results indicated that the combination of nisin and sodium diacetate could be the best preservative effect against all tested strains. • E. faecalis , C. farmei and B. cereus were associated with spoilage of Jinhua ham. • E. faecalis and E. faecium showed a great capacity to produce tyramine and cadaverine. • The combination of nisin and sodium diacetate showed the best preservative effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • The peptides responsible for bitter defects of Jinhua ham were identified by LC-MS/MS. • PKAPPAK, VTDTTR and YIIEK were the key bitter components in defective ham. • Hydrophobic interaction and hydrogen bond were the key forces during the binding of hT2R16 and the peptides. • AMPK pathway, cAMP pathway and calcium signaling pathway were mainly responsible for the signal transduction of VTDTTR. In order to identify the peptides responsible for bitter defects and to understand the mechanism of bitterness in dry-cured ham, the peptides were identified by LC-MS/MS, and the interaction between bitter peptides and receptor proteins were evaluated by molecular docking and molecular dynamics simulation; the signal transduction mechanism of bitter peptides was investigated using the model of HEK-293T cells by calcium imaging and transcriptomics analysis. The results of LC-MS/MS showed that 11 peptides were identified from the high bitterness fraction of defective ham; peptides PKAPPAK, VTDTTR and YIIEK derived from titin showed the highest bitterness values compared with other peptides. The results of molecular docking showed that lower CDOCKER energy was observed in the interaction between these peptides and hT2R16 in comparison with these receptors of hT2R1, hT2R4, hT2R5, hT2R8 and hT2R14, and the interaction of hT2R16 and peptides was stabilized by hydrophobic interaction and hydrogen bond. The average RMSF values of VTDTTR were higher than that of YIIEK and PKAPPAK, while EC 50 values of VTDTTR were lower compared with PKAPPAK and YIIEK. Transcriptomics analysis showed that 529 differentially expressed genes were identified in HEK-293T cells during the stimulating by VTDTTR and were mainly enriched into neuroactive ligand-receptor interaction, MAPK pathway, cAMP pathway and calcium signaling pathway, which were mainly responsible for the bitter signal transduction of VTDTTR. These results could provide evidence for understanding the bitter defects of dry-cured ham and the taste mechanism of bitter peptide. [ABSTRACT FROM AUTHOR]

Meat adulteration is a challenge faced by the global food industry. However, existing protein-based methods or DNA-based polymerase chain reactions are time-consuming and require specialist devices. Therefore, a rapid and on-site assay is urgently needed for identifying meat species. In this study, we developed a duplex recombinase polymerase amplification-lateral flow strip (dRPA-LFS) assay coupled with a rapid DNA extraction method (utilizing the UiO-66 coated stick as the DNA isolation device, and the isolation can be completed in 1 minute, including lysis, washing, and desorption in three steps) for the identification of pork and chicken ingredients. Targeted genes, the pork (Porcine) mitochondrial ND2 gene and chicken (Gallus gallus) cytochrome B gene, were designed with primers and probes. The whole dRPA-LFS detection procedure can be finished within 18.5 minutes (including 1 minute of rapid DNA extraction, 15 minutes of dRPA amplification, and 2.5 minutes of LFS semi-quantitative detection by the naked eye), and the result can also be quantified by ImageJ software within 15 minutes. No positive amplification was observed in beef, lamb, duck, rabbit, goose, ostrich, and horse meat DNA. This assay is sensitive and can detect as low as 0.1 % (wt %) of pork and chicken in simulated adulterated meat mixtures. This assay was successfully applied to the authentication identification of 30 commercial beef and lamb products. • A dRPA-LFS combined with 1-min DNA extraction for meat authentication. • This assay can simultaneously detect pork and chicken within 18.5 min. • This assay also can be quantified by ImageJ software. • The sensitivity of this assay were lower than 0.1 %. • This assay is highly specific and applicable for commercial meat products. [ABSTRACT FROM AUTHOR]

The generation of aroma during processing of boneless dry‐cured hams is investigated by evaluating neutral and acid lipases, phospholipase, lipoxygenase (LOX), thiobarbituric acid reactive substances (TBARS) values, fatty acid composition, and volatile substances derived from lipid oxidation (VCDFLO). It is found that moisture content, acid lipase, and phospholipase decreases in the whole processing, but sodium chloride content and TBARS increase. Neutral lipase, LOX, and total fatty acids increase from raw ham to the end of resting and decrease subsequently. 15 VCDFLO containing six ketones, three aldehydes, three hydrocarbons, one alcohol, one carboxylic acid, and one furan are identified. The total peak area of VCDFLO increases during the entire processing and indicates 39.76–40.75% of total volatile compounds. Hexanal, 1‐octen‐3‐ol, octanal, and nonanal are the major characteristic volatiles of boneless dry‐cured hams. Therefore, VCDFLO formation is associated with lipid‐related enzymes and helpful for the aroma. Practical Applications: The pork that has high intramuscular fat content is usually selected to produce boneless dry‐cured hams, because intramuscular phospholipids, and triglycerides are important precursors to produce aroma compounds. Exploring the formation mechanism of flavor associated with lipid oxidation will be beneficial for improving the quality of hams. Therefore, this study demonstrates the relationship between lipolysis‐oxidation and the generation of flavor compounds during the processing of boneless dry‐cured hams. This study demonstrates that thiobarbituric acid reactive substances (TBARS) values can reveal the changed trend of volatile compounds derived from lipid oxidation (VCDFLO) very well, and that lipid‐related enzymes plays an important role in the development of VCDFLO. [ABSTRACT FROM AUTHOR]

[Display omitted] • Staphylococcus on proteolysis and taste parameters of dry-cured bacon was studied. • Staphylococcus inoculation accelerated protein degradation and FAA accumulation. • The breakdown of myosin and actin mainly contributed to FAA release in SX & SV. • Glu, Ala and Lys were mainly responsible for taste improvement of dry-cured bacon. 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. [ABSTRACT FROM AUTHOR]

A solid-phase microextraction (SPME) Arrow and high-performance liquid chromatography-UV detector (HPLC-UV, detection at 225 nm) based method was developed for the selective determination of nine alkylphenols (APs) in milk. The functionalized mesoporous UiO-66 (4-meso-UiO-66) was utilized as the new coating material, which was synthesized by post-modification of pore-expanded UiO-66-NH2 by an esterification reaction with 4-pentylbenzoic acid. It was fully characterized by X-ray photoelectron spectroscopy (XPS), fourier transformation infrared spectrometry, nitrogen sorption-desorption test, scanning electron microscopy, transmission electron microscopy, and X-ray diffractometer. The characterization results showed the ester groups and benzene rings were introduced into the 4-meso-UiO-66, and the mesoporous structure was predominant in the 4-meso-UiO-66. The extraction mechanism of 4-meso-UiO-66 to APs is the synergistic effect of Zr-O electrostatic interaction and the size exclusion effect resulting from XPS, selectivity test, and nitrogen sorption-desorption test. The electrospinning technique was utilized to fabricate the 4-meso-UiO-66 coated SPME Arrow and polyacrylonitrile (PAN) was used as the adhesive. The mass rate of 4-meso-UiO-66 to PAN and the electrospinning time were evaluated. The extraction and desorption parameters were also studied. The linear range of this method was 0.2–1000 μg L–1 with a coefficient of determination greater than 0.9989 under the optimal conditions. The detection limits were 0.05–1 μg L–1, the inter-day and intra-day precision (RSD) were 2.8–11.5%, and the recovery was 83.6%–112%. The reusability study showed that the extraction performance of this new SPME Arrow could be maintained after 80 adsorption-desorption cycles. This method showed excellent applicability for the selective determination of APs in milk. [ABSTRACT FROM AUTHOR]

Strain activity and stability severely limit the beneficial effects of probiotics in modulating host health. Postbiotics have emerged as a promising alternative as they can provide similar or even enhanced efficacy to probiotics, even under inactivated conditions. This review introduces the ingredients, preparation, and identification techniques of postbiotics, focusing on the comparison of the advantages and limitations between probiotics and postbiotics based on their mechanisms and applications. Inactivation treatment is the most significant difference between postbiotics and probiotics. We highlight the use of emerging technologies to inactivate probiotics, optimize process conditions to maintain the activity of postbiotics, or scale up their production. Postbiotics have high stability which can overcome unfavorable factors, such as easy inactivation and difficult colonization of probiotics after entering the intestine, and are rapidly activated, allowing continuous and rapid optimization of the intestinal microecological environment. They provide unique mechanisms, and multiple targets act on the gut–organ axis, co‐providing new clues for the study of the biological functions of postbiotics. We summarize the mechanisms of action of inactivated lactic acid bacteria, highlighting that the NF‐κB and MAPK pathways can be used as immune targeting pathways for postbiotic modulation of host health. Generally, we believe that as the classification, composition, and efficacy mechanism of postbiotics become clearer they will be more widely used in food, medicine, and other fields, greatly enriching the dimensions of food innovation. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study identified umami and umami-enhancing peptides, which explain the umami taste of Sanhuang chicken. Ten novel peptides were isolated from chicken hydrolysate by gel filtration chromatography and reverse-phase high-performance liquid chromatography. The amino acid sequence was analyzed by UPLC-Q-Exactive Orbitrap-MS: HGEDKEGE, IPIPATKT, SEASNNK, IGPGLGR, AGDDAPR, FAGDDAPR, ADGLWL, KDGGGGK, PGPAGPAGP, and GFLGPQ. All synthetic peptides were discovered with umami and umami-enhancing effects based on the sensory evaluation and electronic tongue. Of these, HGEDKEGE, and SEASNNK showed a prominent umami taste, and the umami threshold values of the umami peptide were 0.56 and 0.33 mmol/L, respectively. The AGDDAPR and IGPGLGR had better a umami-enhancing effect. The molecular docking results confirmed that all peptides entered the Venus flytrap (VFT) domain of T1R3, new binding sites were obtained, Arg303, Ser123, and His121 might play critical roles in the umami-enhancing effects. Residues of Ser146 and Ser123 were found to play decisive roles in umami taste. [ABSTRACT FROM AUTHOR]