Effect of different salt additions on the taste and flavor-related compounds in chicken soup.

Chicken soup is popular among consumers because of its delicious taste, strong flavor, and abundant nutritional value. Twenty-four Yunnan local hens were stewed by adding different amounts of NaCl [1.5, 2, 2.5, 3%, m/m, calculated based on chicken carcass weight; chicken: water = 1:2 (m/m)] to study the effect of salt addition on taste- and flavor-related compounds in chicken soup. Sensory evaluation results showed that the 2 and 2.5% NaCl treatment groups had higher scores. Water-soluble small molecule compounds were detected by LC-Q/TOF-MS based metabolomics approach, among which amino acids and their derivatives, nucleic acids, and small peptides were the main components. The concentration of Water-soluble small molecule substances in chicken soup samples with different salt additions showed a clear trend of separation and reached the highest in the 2.5% NaCl treatment group. Volatile flavor compounds in the chicken soup were analyzed by HS-SPME-GC-MS, including aldehydes, and alcohols, and the relative concentration of flavor compounds in the 2.5% salt treatment group was the highest. In summary, the addition of salt could improve the overall flavor of chicken broth, and the optimal salt addition of NaCl in chicken soup is 2.5%.

Identification of umami peptides from Wuding chicken by Nano-HPLC-MS/MS and insights into the umami taste mechanisms.

Wuding chicken is popular with consumers in China because of its umami taste. This study aimed to identify novel umami peptides from Wuding chicken and explore the taste mechanism of umami peptides. The molecular masses and amino acid compositions of peptides in Wuding chicken were identified by nano-scale liquid chromatography-tandem mass spectrometry (Nano-HPLC-MS/MS). The taste characteristics of the peptides synthesized by the solid-phase method were evaluated by sensory evaluation combined with electronic tongue technology. The secondary structure of the peptides was further analyzed by circular dichroism (CD), and the relationship between the structure and taste of the peptides was elucidated by molecular docking. The results showed that eight potential umami peptides were identified, among which FVT (FT-3), LDF (LF-3), and DLAGRDLTDYLMKIL (DL-15) had distinct umami tastes, and FT-3 had the highest umami intensity, followed by LF-3 and DL-15. The relative contents of ß-sheets in the three umami peptides were 55.20%, 57.30%, and 47.70%, respectively, which were the key components of Wuding chicken umami peptides. In addition to LF-3 embedded in the cavity-binding domain of the TIR1, both FT-3 and DL-15 were embedded in the venus flytrap domain (VFTD) of the T1R3 to bind the umami receptor T1R1/T1R3. The main binding forces between the umami peptides and the umami receptor T1R1/T1R3 relied on hydrogen bonds and hydrophobic interactions, and the key amino acid residues of the combination of umami peptides and the umami receptor T1R1/T1R3 were Glu292, Asn235, and Tyr262.

Identification and Characterization of Novel Umami Peptides from Protein Hydrolysates of Morchella esculenta and Their Interaction with T1R1/T1R3 Receptor.

The study aimed to explore umami peptides derived from protein hydrolysates of Morchella esculenta. According to the electronic tongue and sensory evaluation, the ultrafiltration fractions (<3 kDa) of the protein hydrolysates exhibited the strongest umami taste. The overall flavor of the screened fractions was significantly improved after the Maillard reaction, based on the electronic nose and electronic tongue analyses, and the content of total free amino acid increased from 387.35 to 589.30 µg/mL. A total of 37 peptides with high confidence were identified from the fractions using LC-MS/MS. Additionally, two novel umami peptides were screened through bioinformatics and molecular docking, and their recognition threshold was 0.43 (EYPPLGRFA) and 0.52 mmol/L (TVIDAPGHRDFI), respectively. In addition, molecular docking analysis revealed that the key binding sites, such as Ser148, Leu51, Arg327, and Leu468 in T1R1/T1R3 contributed to docking, and hydrogen bonding and hydrophobic interactions were the dominant interaction forces between the two umami peptides and T1R1/T1R3 receptor. This study contributes to the development and utilization of Morchella esculenta in flavored foods.

Combined application of high-throughput sequencing and LC-MS/MS-based metabolomics to evaluate the formation of Zn-protoporphyrin in Nuodeng ham.

In order to deepen the understanding of the formation mechanism of Zn-protoporphyrin (ZnPP), Nuodeng ham was used as the research object, and the effects of bacterial communities and small molecule metabolites on the formation of ZnPP during the processing of Nuodeng ham were analyzed by high-throughput sequencing and LC-MS/MS-based metabolomics. With the prolongation of processing time, the ZnPP content increased significantly, while the heme content decreased significantly. Compound curing agent significantly inhibited the formation of ZnPP and significantly decreased the heme content. The bacterial communities changed dynamically and the five bacterial genera were significantly positively correlated with ZnPP content. Forty-seven differential metabolites were obtained through screening, of which seventeen differential metabolites were significantly positively correlated with ZnPP content. Correlation analysis showed a strongly positive correlation between Staphylococcus, Delftia, Acinetobacter and these seventeen differential metabolites. These findings can provide a theoretical basis for further establishing the color control measures of Nuodeng ham.

Selegiline Protects Against Lipopolysaccharide (LPS)-Induced Impairment of the Blood-Brain Barrier Through Regulating the NF-κB/MLCK/p-MLC Signaling Pathway.

Disruption of the blood-brain barrier (BBB) is an important hallmark of sepsis-associated encephalopathy (SAE). Selegiline, a selective and irreversible inhibitor of monoamine oxidase type B, has been applied for the treatment of nervous disorders. In this study, we aimed to investigate whether selegiline has a protective capacity in the impairment of the BBB in both in vivo and in vitro experiments. In a sepsis mouse model, administration of selegiline ameliorated lipopolysaccharide (LPS)-induced impairment of BBB integrity. Additionally, treatment with selegiline increased the expression of the tight junction protein junctional adhesion molecule A (JAM-A) against LPS. Also, we found that selegiline inhibited the production of the proinflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-1ß. In an in vitro experimental model, bEnd.3 brain endothelial cells were exposed to LPS. Results indicate that stimulation with LPS significantly increased the permeability of bEnd.3 cells and reduced the expression of JAM-A, both of which were rescued by treatment with selegiline. Additionally, selegiline prevented the activation of the NF-κB/MLCK/p-MLC signaling pathway in LPS-challenged bEnd.3 cells. These results indicate that selegiline exerted a protective effect on BBB dysfunction, which might be attributed to the inhibition of the NF-κB/MLCK/p-MLC signaling pathway. These findings provide a basis for further research into the neuroprotective mechanism of selegiline.

The protective effects of Mirtazapine against lipopolysaccharide (LPS)-induced brain vascular hyperpermeability.

Sepsis is mainly characterized by severe inflammation triggered by infection, and sepsis-associated encephalopathy (SAE) is defined as brain damage caused by sepsis. Disruption of the blood-brain barrier (BBB) triggered by injured brain microvascular endothelial cells (BMECs) and damaged tight junction (TJ) structure is closely associated with the pathogenesis of SAE. The present research proposed to evaluate the potential therapeutic effects of Mirtazapine, a central presynaptic α2 receptor antagonist, on LPS-induced BBB disruption. The mice were administered with normal saline and 10 mg/kg Mirtazapine for 8 consecutive days, and from day 6, the experiment group of mice received LPS for 2 days to induce SAE. We found that the increased BBB permeability, elevated concentrations of inflammatory factors in brain tissues, and downregulated zonula occludens -1 (ZO-1) were observed in LPS-stimulated mice, all of which were reversed by 10 mg/kg Mirtazapine. In the in vitro assay, bEnd.3 brain endothelial cells were treated with 1 µM LPS in the absence or presence of Mirtazapine (25, 50 µM). We found that LPS-treated cells had significantly declined transendothelial electrical resistance (TEER), increased monolayer permeability, elevated production of inflammatory factors, and downregulated ZO-1. However, 25 and 50 µM Mirtazapine ameliorated all these LPS- induced aberrations. Mirtazapine also mitigated the decreased level of NF-E2-related factor 2 (Nrf2) in LPS-challenged endothelial cells. The protective effect of Mirtazapine on endothelial permeability against LPS was significantly abolished by the knockdown of Nrf2. Collectively, we concluded that Mirtazapine exerted protective effects on LPS-induced endothelial cells hyperpermeability by upregulating Nrf2.

Comparative proteome analysis of matured dry and germinating Moringa oleifera seeds provides insights into protease activity during germination.

This study is the first to apply label-free based proteomics to investigate the proteome changes during Moringa oleifera seed germination. In total, 1267 proteins were identified, with proteins within the molecular weight range of 10-60 kDa being most abundant. Among the 174 differentially expressed proteins (DEPs), 42 were upregulated and 26 downregulated, whereas 45 and 61 were uniquely expressed in the matured dry and germinating seeds, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the main DEPs had significant molecular functions related to catalytic activity and were involved in metabolism, degradation and biosynthesis, with 49 enzymes highly expressed in germination, including 9 proteases with hydrolytic activity, of which a peptidase and three types of endopeptidases were associated with milk-clotting activity. We further demonstrated that proteolytic activity (PA) and milk-clotting specific activity (MCSA) of protease extracts from M. oleifera seeds were increased during germination, particularly for samples from the ammonium sulfate (AS) fractionation that were statistically significance (p value < 0.05). Overall, proteases derived from germinating M. oleifera seeds can be used in the food industry, especially for potential application in the production of bioactive peptides and cheese processing.

Purification, characterization and immunomodulatory activity of polysaccharides from Leccinum crocipodium (Letellier.) Watliag.

The polysaccharide obtained from edible fungi has been regarded as the major bioactive component related to the nutritional and human's health. In the present study, three purified polysaccharides (LCP-1, LCP-2, and LCP-3) were obtained from Leccinum crocipodium (Letellier.) Watliag. The characterizations of LCP-1, LCP-2, and LCP-3 were determined by high-performance liquid chromatography (HPLC), UV, FT-IR spectrometrys and 1H NMR spectrum. LCP-1 had a molecular weight of 2.303 × 105 Da and 7.519 × 103 Da, and was composed of mannose (Man), ribose (Rib), rhamnose (Rha), glucuronic acid (GluA), galacturonic acid (GalA), glucose (Glu), galactose (Gal), xylose (Xyl), arabinose (Ara) and fucuronic (Fuc). The molecular weight of LCP-2 was 2.655 × 105 Da, and its monosaccharide constituents were Man, Rib, Rha, GluA, Glu, Gal, Xyl, Ara and Fuc. The molecular weight of LCP-3 was 3.783 × 105 Da, and its monosaccharide constituents were Man, Rib, Rha, GluA, GalA, Glu, Gal, Xyl, Ara and Fuc. For the in vitro immunomodulatory experiments demonstrated that three purified polysaccharides could enhance immunomodulatory activities on macrophage RAW 264.7 cells, moreover, LCP-2 and LCP-3 showed stronger immunomodulatory activity than LCP-1. The results indicated that the LCP-1, LCP-2, and LCP-3 could be further developed as functional food or medicine.

Metal-organic frameworks supported surface-imprinted nanoparticles for the sensitive detection of metolcarb.

A novel approach to synthesize molecularly imprinted polymer (MIP) nanoparticles using a MIL-101 support (a type of metal-organic framework) is reported herein for the first time; the sample is referred as MIL@MIP. The nanoparticles were well distributed within the polymer film, and exhibit an octahedral shape, satisfied thermal stability, and a high specific surface area (SSA) of 1579.43 m(2)g(-1). The adsorption behavior of MIL@MIP toward metolcarb in aqueous solution was subsequently examined. The synthesized MIL@MIP displayed satisfactory high transfer mass rates and a high selective adsorption affinity for metolcarb. Based on these results, a quartz crystal microbalance (QCM) sensor based on MIL@MIP was subsequently constructed and examined for the sensitive detection of metolcarb. Under optimal conditions, the detection limit of the system assessed in pear juice was 0.0689 mg L(-1) within a linear concentration range of 0.1-0.9 mg L(-1). MIL@MIP-QCM system combines the advantages of MIL-101 and molecularly imprinted technology (MIT), thereby achieving high detection sensitivity and selectivity. The current findings suggest the potential of MIL@MIP for detecting trace level pesticides and veterinary drugs for food safety and environmental control.