摘要：
Acid adaptation in Salmonella Enteritidis was characterized by phenotypic and gene-expression analyses. S. Enteritidis cells at log-phase and stationary-phase were kept at pH 4.5 to 6.0 for 1 to 4 hours. All treatments induced various levels of acid tolerance response that were dependent on pH, exposure time and growth phase. This acid adaptation resulted in tolerance to 50 degrees C and 8% NaCl regardless of the growth phase. However, the tolerance of log-phase and stationary-phase cells to low temperatures (4 and -20 degrees C) was increased and decreased, respectively. RT-qPCR analysis revealed that genes involved in tolerance to acid (SEN1564A and cfa), heat (rpoH, uspB, and htrA), salt (proP, proV, and osmW), and cold (cspA, cspC, and csdA) stress were generally upregulated after acid adaptation. These results provide an initial insight into mechanisms of acid adaptation and induced cross protection in S. Enteritidis. PRACTICAL APPLICATION: Stress tolerance acquisition resulting from acid adaptation in foodborne pathogens poses a great threat to food safety. The current work showed that acid adaptation induced direct tolerance and cross-tolerance to high temperature, low temperature, and salt in Salmonella Enteritidis, possibly due to the upregulation of stress tolerance-related genes. These results provide key insights into acid adaptation mechanisms and efficient control of S. Enteritidis.
关键词：
Maillard reaction;Pickering emulsion;curcumin;thermal stability;whey protein
摘要：
In this study, whey protein isolates (WPI), lactose (Lac) Maillard-reacted products, and epigallocatechin gallate (EGCG) complex were used to enhance the thermal stability of the Pickering emulsion delivery of curcumin. Atomic force microscopy combined with Fourier transform infrared spectroscopy were employed to study the morphological characteristics and structural changes of WPI-Lac/EGCG nanoparticles. Results proved that WPI-Lac and EGCG were combined by hydrogen bonding and hydrophobic interaction. The mechanism underlying WPI-Lac/EGCG-stabilized Pickering emulsion was further characterized by confocal laser scanning microscopy. The optimal binding ratio of WPI-Lac to EGCG was 1:1 (w/w) at pH 3.0. The particle size and zeta potential of the WPI-Lac/EGCG nanoparticles were about 110 nm and 27 mV, respectively. Analysis of microstructure and droplet size distribution revealed that the glycated WPI-Lac/EGCG-stabilized emulsions exhibited more uniform droplet distribution, stronger thermal stability, and higher curcumin percentage retention than WPI. These results indicate that the WPI-Lac/EGCG nanoparticles are potential stabilizers for Pickering emulsion requirements. This study provides a basis for the construction of Pickering emulsion systems while carrying pro-/hydrophobic bioactive components.
关键词：
Nepsilon-(carboxymethyl)lysine;immune response;oxidative stress;receptor for advanced glycation end products
摘要：
Nepsilon-(carboxymethyl)lysine (CML), which is a compound produced when food is processed, has aroused concern in recent years because of its potentially dangerous effects. This study aimed to investigate the mechanism of free CML-induced toxic injury in mice. The inflammatory cytokine tumor necrosis factor-alpha, transforming growth factor-beta, vascular cell adhesion molecule-1 mRNA expression levels of CML-infected mice liver and kidney tissues significantly increased. While CML receptor-receptor for advanced glycation end products (RAGE) protein expression in male mice liver tissue had a more significant change than the control group, there was no significant difference in other dose groups compared with the control group. In conclusion, the foodborne free CML can be induced by oxidative stress and immune response to liver and kidney tissue injury in mice. Additionally, the free CML may also bind to RAGE, which activates the downstream inflammatory pathway.
摘要：
beta-Cyclodextrin (beta-CD) was modified using octenyl succinic anhydride (OSA) to introduce amphiphilic groups (hydrophilic carboxyl and lipophilic octenyl chains) by esterification under alkaline conditions. The FT-IR results indicated that the OSA-modified beta-CD (OCD) showed new absorption peaks of an ester bond and a carboxylate (RCOO(-)) at 1724 and 1570 cm(-1), respectively, confirming the successful preparation of OCD. Then the embedding effects of beta-CD and OCD on beta-carotene and the emulsifying and antioxidant properties of their inclusion complexes were evaluated. The results of XRD showed that the beta-CD (or OCD)/beta-carotene inclusion complexes were converted from a cage-type structure to a channel-type structure. AFM and SEM showed that the crystal characteristics and surface morphologies of the inclusion complexes were different from those of the physical mixture. The emulsion stabilized by OCD exhibited smaller droplet sizes and larger zeta-potentials than that stabilized by beta-CD. In addition, the inclusion complexes-prepared emulsion exhibited lower POV values and TBARS contents than did the physical mixture. OCD/beta-carotene inclusion complexes can improve the physical and oxidative stability of the emulsion, which is of great significance to the food industry.
关键词：
Jerusalem artichoke;compression kinetic;diffusion;inulin;pulsed electric field
摘要：
Jerusalem artichoke is widely used as raw material for industrial production of inulin. Pressing (compression) and diffusion are two effective technologies for bio-compounds' recovery from plants. In this work, pulsed electric field (PEF) treatment at 400, 600, and 800 V/cm during 100 ms was applied to facilitate juice and solutes recovery from Jerusalem artichoke. The application of PEF led to electroporation of cell membranes and enhanced the tissue compression/juice expression and solutes diffusion. The consolidation coefficient (calculated by application of semi-empirical model) of PEF treated sample at 800 V/cm was 6.50 x 10(-7) m(2)/s, which is significantly higher than that of untreated sample (5.02 x 10(-9) m(2)/s) and close to that of freeze-thawed sample. Diffusion experiments with PEF treated samples were carried out at 25, 50, and 75 degrees C. A PEF treatment of Jerusalem artichoke at 800 V/cm led to a similar diffusion behavior at 25 degrees C, compared to diffusion behavior obtained from untreated sample at 75 degrees C.
摘要：
It has been proven that A-type procyanidins, containing an additional ether bond, compared to B-type procyanidins are also bioavailable in vitro and in vivo. However, their bioavailability and absorption in the gastrointestinal tract remain uncertain. In this study, a model of the human adenocarcinoma stomach cell line (MKN-28) was established to explore the cellular transport of flavanolic monomers and procyanidin dimer A2, which were isolated from the litchi pericarp extract. After the integrity and permeability of the cell monolayer were ensured by measurement of the transepithelial electrical resistance and the apparent permeability coefficient for Lucifer yellow, the transportation of procyanidins A2 and B2, (-)-epicatechin (EC), and (+)-catechin (CC) was studied at pH 3.0, 5.0, or 7.0 in the apical side, with compound concentrations of 0.05 and 0.1 mg/mL based on the cytotoxicity test. High-performance liquid chromatography and liquid chromatography-mass spectrometry analyses indicated that EC, CC, and A2 were transported in the MKN-28 cell line from 30 to 180 min, while B2 showed no transport. The maximal transport efficiencies of EC, CC, and A2 were 23 +/- 0.81, 13.16 +/- 1.53, and 16.41 +/- 1.36%, respectively, existing at 120, 180, and 120 min of transportation. Laser scanning confocal microscopy analysis presented the dynamic transmission of EC, in accordance with the result of concentration determination, suggesting that the A-type procyanidins are possibly absorbed through the stomach barrier, which is pH- and time-dependent.
摘要：
Jerusalem artichoke is an important natural matrix for inulin production. In this experiment, response surface methodology (RSM) was employed to optimize the spray-drying parameters in order to determine the maximal inulin yield. For this study, three independent variables (heating temperature (T, 110-120 degrees C), creep speed (V, 18-22 rpm) and pressure (P, 0.02-0.04 MPa)) were used in the experimental design. Using the Box-Behnken design, the optimal parameters obtained were: drying temperature 114.6 degrees C, creep speed 20.02 rpm, and pressure: 0.03 MPa. The inulin yield, water content and particle size of inulin obtained by spray-drying and freeze-drying were compared. In this regard, the spray-dried inulin consisted of a white powder having a fine particle size, and the freeze-dried inulin had a pale-yellow fluffy floc. On the other hand, the drying methods had a great influence on the appearance and internal structure of inulin powder, since the spray-dried inulin had a complete and uniform shape and size, whereas the freeze-dried inulin had a flocculated sheet structure. The analysis showed that the spray-drying led to a higher inulin yield, lower water content and better surface structure than freeze-drying.
摘要：
3-Monochloropropane-1,2-diol (3-MCPD) is a common food processing contaminant and a simple, rapid, sensitive and low cost monitoring technology is needed due to its potential carcinogenic nature. Carbon dots directly intercepted on filter paper provide high fluorescence intensity and can be adapted for use as a sensor. We synthesized a carbon dot-filter paper in combination with a molecularly imprinted polymeric film to extract 3-MCPD from samples. This grafted paper-based sensor exhibited a high adsorption capacity (68.97mgg(-1)), an excellent selectivity (imprinting factor=4.5) and a low detection limit (0.6ngmL(-1)). Recoveries ranged from 97.2% to 105.3% with relative standard deviations <5.6%. The results obtained using this method were linearly correlated to those of the classic GC-MS method (r=0.998). Based on the Chinese National Standard, this study provides a novel and powerful platform for the simple, rapid, sensitive and on-site analysis of 3-MCPD in soy sauce.
摘要：
Purple sweet potato anthocyanins are common natural pigments widely used in food industry, while they are often thermally processed in application. Degradation of anthocyanins, formation of polymers and color changes of purple sweet potato extract (PSPE) were investigated at 90 degrees C in the range of pH 3.0-pH 7.0. Data analysis indicated a first-order reaction for anthocyanins degradation in solutions with pH 3.0, 5.0 and 7.0 have half-lives of 10.27, 12.42 and 4.66h, respectively. The polymeric color formation followed zero-order kinetics, progressively increasing with pH values. The color of PSPE were changed with heating time and pH value through visual observation and colorimetric characterization. Analysis by UV-Vis spectrophotometry and HPLC indicated that anthocyanins in solution with pH 3.0 changed from monomeric anthocyanin into new polymers during heat treatment. Degradation of anthocyanins was accompanied by an increase in polymeric color index, due to the formation of melanoidin pigments and condensation reactions.
摘要：
The effects of amino acid-involved Maillard reactions (MRs) on the structure and activities of longan pulp polysaccharides (LPs), which were heteropolysaccharides mainly composed of glucose, galactose, mannose, rhamnose, glucuronic acid, ribose, and galacturonic acid, were investigated. The changes of browning degree and molecular weight (M-w) distribution in the MR systems containing LPs and amino acids (lysine, proline, or glycine) indicated that lysine was more active in conjugating with LPs. The MR-modified LPs (MLPs) obtained via a 4 h MR between LPs and lysine showed obvious structural differences from LPs. Specifically, particle-like LPs contained 94% fractions with a M-w less than 7.07 kDa, by contrast, network-like MLPs contained 45% fractions with a M-w larger than 264.1 kDa. Moreover, MLPs showed stronger radical scavenging abilities and macrophage immunostimulating effects, but weaker cancer cell growth-inhibitory abilities. The results indicate that the amino acid-involved MR is a promising method to modify native polysaccharides for better biological properties.
关键词：
Indoor particulate matter;Oxidative stress;Inflammation;Promote coagulation;3D human microvessel
摘要：
BACKGROUND: A growing body of evidence shows that indoor concentrations of airborne particles are often higher than is typically encountered outdoors. Since exposure to indoor PM2.5 is thought to be associated with cardiovascular disease, the health impacts of indoor air pollution need to be explored. Based on animal models, ambient particulate matter has been proved to promote coagulation which is very likely involved in the pathogenic development of cardiovascular disease. However, animal models are insufficient to predict what will happen with any certainty in humans. For this reason, the precise pathogenic mechanisms behind the development of cardiovascular disease in humans have not yet been determined. RESULTS: We generated a 3D functional human microvascular network in a microfluidic device. This model enables human vascular endothelial cells to form tissue-like microvessels that behave very similarly to human blood vessels. The perfusable microvasculature allows the delivery of particles introduced into these generated human-like microvessels to follow the fluid flow. This exposure path effectively simulates the dynamic movement of airborne nanoscale particles (ANPs) within human vessels. In this study, we first identified the existence of ANPs in indoor air pollution. We then showed that ANPs could activate endothelial cells via ROS induced inflammation, and further resulted in abnormal expression of the coagulation factors (TF, TM and t-PA) involved in coagulation cascades. In addition, we found that a protein could cover ANPs, and this biointeraction could interfere with heparan sulfate (HS). Human organotypic 3D microvessel models provide a bridge for how research outcomes can translate to humans. CONCLUSIONS: The 3D human microvessel model was used to determine the physiological responses of human vessels to ANP stimulation. Based on the obtained data, we concluded that ANPs not only disrupts normal coagulation functions, but also act directly on anticoagulant factors in human vessels. These experimental observations provide a potential biological explanation for the epidemiologically established link between ANPs and coagulation abnormality. This organ-on-chip model may provide a bridge from in vitro results to human responses.
摘要：
To investigate the structure, in vitro digestibility and activity of polysaccharides from lotus root, their main fractions named LRPs were isolated and purified by gel filtration chromatography. Structural analyses indicated that: LRPs were alpha-(1 -> 6)-D-heteroglucans mainly composed of Glc-(1 ->, -> 6)-Glc(1 ->, -> 6)-Gal (1 ->, -> 4,6)-Gal- (1 -> and -> 3,6)-Glc-(1 ->, at a molar ratio of 1.00: 4.33: 0.83: 0.13: 1.14; the total molar percentage of other monosaccharides in LRPs, including Man, Rha, GalA and Ara, was 8.10%; the molecular weights of LRPs was in the range of 1.33 kDa to 5.30 kDa. According to the change of molecular weight and the productions of reducing sugar and free monosaccharide, the simulated experiments of salivary, gastric and intestinal digestion confirmed that LRPs were almost undigestible. Moreover, LRPs showed the scavenging ability against DPPH and hydroxyl radicals, the growth inhibition ability against SGC7901 and HepG2 cancer cells in vitro, and the immunostimulating effect on the NO and TNF-alpha productions of macrophages in vitro. LRPs nearly remain their initial structure and activities in upper gastrointestinal tract and have health-improving potentials. (C) 2019 Published by Elsevier B.V.
关键词：
Near-infrared spectroscopy;Partial least squares;Phytosterol;Vegetable oil;Wavelength selection
摘要：
Phytosterols have been extensively studied because it plays essential roles in the physiology of plants and can be used as nutritional supplement to promote human health. We use a rapid method by coupling near-infrared spectroscopy (NIRS) and chemometric techniques to quickly and efficiently determine three essential phytosterols (beta-sitosterol, campesterol and stigmasterol) in vegetable oils. Continuous wavelet transform (CWT) method was adopted to remove the baseline shift in the spectra. The quantitative analysis models were constructed by partial least squares (PLS) regression and randomization test (RT) method was used to further improve the models. The optimized models were used to calculate the phytosterol contents in prediction set in order to evaluate their predictability. We have found that the phytosterol contents obtained by the optimized models and Gas Chromatography/Mass Spectrometry (GC/MS) analysis are almost consistent. The root mean square error of prediction (RMSEP) and ratio of prediction to deviation (RPD) for the three phytosterols are 525.7590, 212.2245, 65.1611 and 4.0060, 4.7195 and 3.5441, respectively. The results have proved the feasibility of the proposed method for rapid and non-destructive analysis of phytosterols in edible oils.
摘要：
Dietary polyphenols have shown hypolipidemic effects by reducing triglyceride absorption. The mechanisms may involve modifying fat emulsion during digestion in the gastrointestinal tract and suppressing lipase during hydrolysis in the small intestine. In an in vivo study, lotus seedpod oligomeric procyanidin (LSOPC) decreased total serum triglyceride and total cholesterol and elevated the high-density lipoprotein level in the hyperlipidemic rat model. In addition, LSOPC suppressed de novo lipogenesis-related gene expressions. In an in vitro study, the LSOPC-enriched emulsion decreased the mean droplet size from 0.36 to 0.33 mum and increased the viscosity of the emulsion. Moreover, the LSOPC-enriched emulsion improved the antioxidant properties. A digestion model was developed and showed that the particle size of the LSOPC-enriched emulsion increased in the oral cavity. However, an increase and then a significant drop of the particle size was measured in the stomach and small intestine. The free fatty acid release rate was decreased in the LSOPC-enriched emulsion partly ascribed to the inhibition of lipase by LSOPC.
摘要：
High throughput genome sequencing has revealed a multitude of potential secondary metabolites biosynthetic pathways that remain cryptic. Pathway reconstruction coupled with genetic engineering via heterologous expression enables discovery of novel compounds, elucidation of biosynthetic pathways, and optimization of product yields. Apart from Escherichia coli and yeast, fungi, especially Aspergillus spp., are well known and efficient heterologous hosts. This review summarizes recent advances in heterologous expression of microbial secondary metabolite biosynthesis in Aspergillus spp. We also discuss the technological challenges and successes in regard to heterologous host selection and DNA assembly behind the reconstruction of microbial secondary metabolite biosynthesis.
摘要：
Ultra-high pressure technology has attracted a great deal of attention in recent years, and has been widely used in food science, medicine, and other fields. This study aimed to determine the effect of ultra-high pressure on the structure and properties of collagen. Native collagen extracted from bullfrog skin was processed under different ultra-high pressure treatment conditions (300, 400, and 500 MPa). Then systematic analysis of the molecular structures and properties of the samples after ultra-high pressure treatment were performed. It was found that the conformation of collagen molecules could be adjusted by ultra-high pressure treatment, and this regulation was closely related to the level of treatment pressure. A possible mechanism of the impact of ultra-high pressure on the collagen molecular structures was speculated according to the experimental results. At low pressure levels (300-400 MPa), the pressure perpendicular to collagen axis dominates and leads to a tightening of the triple helix structure of collagen, while the pressure parallel to collagen axis is dominant and the triple helix tends to dissociate like a zipper at high pressure levels (> 400 MPa). These structural changes would simultaneously result in various changes to thermal stability, self-assembly properties, and antigenicity of collagen. (C) 2018 Elsevier B.V. All rights reserved.
