Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Food Res Int ; 182: 114034, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38519197

RESUMO

Ultrasound-assisted extraction (UAE) is an intensified mass transfer process, which can utilize natural resources effectively, but still lacks detailed mechanisms for multiscale effects. This study investigates the mass transfer mechanisms of UAE combined with material's pore structure at multiscale. Porous material was prepared by roasting green coffee beans (GCB) at 120 °C (RCB120) and 180 °C (RCB180), and their UAE efficiency for phytochemicals (caffeine, trigonelline, chlorogenic acid, caffeic acid) were evaluated by experiment and modeling. Besides, the physicochemical properties, mass transfer kinetics, and multi-physical field simulation were studied. Results indicated that positive synergy effects on extraction existed between ultrasound and material's pore structure. Higher mass transfer coefficients of UAE (GCB 0.16 min-1, RCB120 0.38 min-1, RCB180 0.46 min-1) was achieved with higher total porosity (4.47 %, 9.17 %, 13.52 %) and connected porosity (0 %, 3.79 %, 5.98 %). Moreover, simulation results revealed that micro acoustic streaming and pressure difference around particles were the main driving force for enhancing mass transfer, and the velocity (0.29-0.36 m/s) increased with power density (0.64-1.01 W/mL). The microscale model proved that increased yield from UAE-RCB was attributed to internal convection diffusion within particles. This study exploited a novel benefit of ultrasound on extraction and inspired its future application in non-thermal food processing.


Assuntos
Ácido Clorogênico , Porosidade
2.
Appl Microbiol Biotechnol ; 107(21): 6641-6653, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37682300

RESUMO

This study aimed to evaluate the antibacterial activities of α-terpineol against common foodborne pathogenic bacteria by agar well diffusion, broth microdilution, and colony counting assay. Propulsive research was conducted to reveal the antibacterial mechanisms, including morphology, infrared spectroscopy, membrane fluidity, membrane permeability, proton motive force, and oxidative phosphorylation. Results indicated that the antibacterial activity of α-terpineol decreased in the following order: Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, and Staphylococcus aureus. With an initial cell count of 8 log CFU/mL, α-terpineol at 0.8% (v/v) reduced E. coli O157:H7 and S. aureus by approximately 5.6 and 3.9 log CFU/mL within 1 h, respectively. Remarkable destruction in cell envelopes and intracellular organizations was observed. The hydroxyl of α-terpineol might form glycosidic bonds with carbohydrates and hydrogen bonds with PO2- and COO- via infrared spectroscopy analysis. Generalized polarization of Laurdan revealed that the polar head groups of phospholipids transformed into close packed. The anisotropy variations of trimethyl amino-diphenylhexatriene (TMA-DPH) and DPH suggested membrane fluidity decreased. The N-phenyl-1-naphthylamine intake assay indicated that α-terpineol impaired the cell wall. Propidium iodide staining was indicative of damaged plasma membranes. Electron transport in the cytoplasmic membrane was impaired, inducing reactive oxygen species accumulation. Both membrane electrical potential and membrane pH gradient collapsed. The disruption of proton motive force and the leakage of ATP resulted in a deficit of intracellular ATP. Our research revealed the interaction between the hydroxyl group of α-terpineol and bacteria affects membrane function contributing to the bacteria's death. KEY POINTS: • α-Terpineol hydroxy formed glycosidic bonds and hydrogen bonds with bacteria • α-Terpineol increased the membrane gelation and reduced the membrane fluidity • Proton motive force and oxidative phosphorylation were impaired.


Assuntos
Escherichia coli O157 , Listeria monocytogenes , Microbiologia de Alimentos , Staphylococcus aureus , Contagem de Colônia Microbiana , Antibacterianos/farmacologia , Trifosfato de Adenosina
3.
Ultrason Sonochem ; 98: 106523, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37453258

RESUMO

Ultrasound is a green nonthermal technology with promising applications in microbial inactivation. Electrolyzed water has been investigated and found to have a synergistic inactivation effect of ultrasound on spores. This study used a data-independent-acquisition method to analyze the stress response of Bacillus cereus spores following ultrasound combined with electrolyzed water treatment. We identified 197 differentially expressed proteins under ultrasound combined with an electrolyzed water treatment for which the ratio in the metabolic pathway was the highest. Spores downregulated key proteins in energy metabolic and transportation pathways, in particular in phosphotransferase systems and ATP synthase under ultrasound, electrolyzed water, and combined stress. The results of this study revealed that the key proteins in intracellular metabolism decreased after ultrasound treatment, and the expression of small acid-soluble spore protein and cell wall biosynthesis protein increased. Meanwhile, DNA integration, recombination, and inversion protein and small acid-soluble spore protein were upregulated after electrolyzed water treatment. In general, the spores exhibited stress resistance under external stress. The inactivation of spores by further stress was reduced, which we called "cross-protection."


Assuntos
Bacillus cereus , Purificação da Água , Esporos Bacterianos/fisiologia , Proteômica , Viabilidade Microbiana
4.
Foods ; 12(12)2023 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-37372636

RESUMO

Starch nanoparticles (SNPs) are generally defined as starch grains smaller than 600-1000 nm produced from a series of physical, chemical, or biologically modified starches. Many studies have reported the preparation and modification of SNPs, which are mostly based on the traditional "top-down" strategy. The preparation process generally has problems with process complexity, long reaction periods, low yield, high energy consumption, poor repeatability, etc. A "bottom-up" strategy, such as an anti-solvent method, is proven to be suitable for the preparation of SNPs, and they are synthesized with small particle size, good repeatability, a low requirement on equipment, simple operation, and great development potential. The surface of raw starch contains a large amount of hydroxyl and has a high degree of hydrophilicity, while SNP is a potential emulsifier for food and non-food applications.

5.
J Integr Plant Biol ; 64(10): 2009-2025, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35929662

RESUMO

The double-recessive genic male-sterile (ms) line ms5 ms6 has been used to develop cotton (Gossypium hirsutum) hybrids for many years, but its molecular-genetic basis has remained unclear. Here, we identified the Ms5 and Ms6 loci through map-based cloning and confirmed their function in male sterility through CRISPR/Cas9 gene editing. Ms5 and Ms6 are highly expressed in stages 7-9 anthers and encode the cytochrome P450 mono-oxygenases CYP703A2-A and CYP703A2-D. The ms5 mutant carries a single-nucleotide C-to-T nonsense mutation leading to premature chain termination at amino acid 312 (GhCYP703A2-A312aa ), and ms6 carries three nonsynonymous substitutions (D98E, E168K, and G198R) and a synonymous mutation (L11L). Enzyme assays showed that GhCYP703A2 proteins hydroxylate fatty acids, and the ms5 (GhCYP703A2-A312aa ) and ms6 (GhCYP703A2-DD98E,E168K,G198R ) mutant proteins have decreased enzyme activities. Biochemical and lipidomic analyses showed that in ms5 ms6 plants, C12-C18 free fatty acid and phospholipid levels are significantly elevated in stages 7-9 anthers, while stages 8-10 anthers lack sporopollenin fluorescence around the pollen, causing microspore degradation and male sterility. Overall, our characterization uncovered functions of GhCYP703A2 in sporopollenin formation and fertility, providing guidance for creating male-sterile lines to facilitate hybrid cotton production and therefore exploit heterosis for improvement of cotton.


Assuntos
Gossypium , Infertilidade das Plantas , Aminoácidos/metabolismo , Códon sem Sentido/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Ácidos Graxos não Esterificados/metabolismo , Fertilidade/genética , Regulação da Expressão Gênica de Plantas/genética , Gossypium/genética , Gossypium/metabolismo , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Nucleotídeos/metabolismo , Fosfolipídeos/metabolismo , Infertilidade das Plantas/genética
6.
Front Microbiol ; 12: 771770, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34803991

RESUMO

Milk is easy to be contaminated by microorganisms due to its abundant nutrients. In this study, a 360-degree radiation thermosonication (TS) system was developed and utilized for the inactivation of Staphylococcus aureus in milk. The 360-degree radiation TS system-induced inactivation kinetics of S. aureus was fitted best by the Weibull model compared with biphasic and linear models. The treatment time, the exposure temperature, and the applied ultrasound power was found to affect the bactericidal efficacy of the 360-degree radiation TS system. Additionally, the TS condition of 200 W and 63°C for 7.5 min was successfully applied to achieve complete microbial inactivation (under the limit of detection value) in raw milk. The treatment of 360-degree radiation TS can enhance the zeta potential and decrease the average particle size of milk. It also exhibited better retainment of the proteins in milk compared with the ultrahigh temperature and conventional pasteurization processing. Therefore, the 360-degree radiation TS system developed in this study can be used as an alternative technology to assure the microbiological safety and retain the quality of milk, and the Weibull model could be applied for the prediction of the inactivation levels after exposure to this technology.

7.
Ultrason Sonochem ; 78: 105732, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34474268

RESUMO

This study was aimed at providing new insights on the proteomic response of bacterial spores to ultrasound. Data-independent-acquisition method was used to quantify the proteome change of Bacillus cereus spores after ultrasound treatment (200 W). This study revealed that 2485 proteins were extracted from Bacillus cereus spores, most of them were related to metabolism. After ultrasound treatment, the expression of 340 proteins were significantly changed (the fold change ≥ 2 and p < 0.05), of which 207 proteins were significantly down-regulated. KEGG pathway analysis showed that differentially expressed proteins mainly distributed in metabolism pathway, cell process pathway and genetic information processing pathway after ultrasound treatment. Furthermore, this study analyzed the differentially expressed proteins in significant enrichment pathways. In particular, the expression of key proteins in the phosphorylation reaction of spores was significantly decreased after ultrasound treatment. Thus, ATP synthesis rate decreased and the phosphorylation reaction inhibited. Also, the decrease of the expression of key proteins related to the tricarboxylic acid cycle led to the decrease of nutrients metabolism of spores. Ultrasound treatment induced the down-regulation of fatty acid synthetase expression and promoted fatty acid metabolism at the same time. The content of fatty acids decreased in spores consequently.


Assuntos
Bacillus cereus , Proteômica , Bacillus cereus/metabolismo , Bacillus cereus/efeitos da radiação , Proteoma , Esporos Bacterianos , Ondas Ultrassônicas
8.
Food Chem ; 362: 130066, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34098434

RESUMO

Cereal germ (CG), a by-product of grain milling, has drawn much attention in the food industry because of its nutritional and functional advantages. Nowadays, the utilization of cereal germ from animal feeds to foodstuff is a popular trend. CGs have high content of polyunsaturated fatty acids in their lipids (43.9-64.9% of total fatty acids), but they are also induced to oxidative rancidity under the catalytic reaction of enzymes. Chemical and structural properties of lipids in CGs are affected by different treatments. Thermal and non-thermal effects prevent lipid oxidation or promote lipid combination with starch/protein in CG. Thus, the functional properties and final quality of CG are directly changed. In this review, the chemical composition and application of CGs especially the endogenous lipids are summarized and the effects of various processes on CG lipids/matrices are discussed for CG future development.


Assuntos
Grão Comestível/química , Lipídeos/química , Ração Animal , Animais , Análise de Alimentos , Indústria Alimentícia , Indústria de Processamento de Alimentos , Lipídeos/análise , Oxirredução , Amido/química
9.
Appl Microbiol Biotechnol ; 104(10): 4505-4513, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32215708

RESUMO

This study evaluated the inactivation effect of ultrasonic treatment combined with acidic electrolyzed water (AEW) on Bacillus cereus spores. AEW treatment reduced the spores by 1.05-1.37 log CFU/mL while the sporicidal effect of ultrasound was minor. More strikingly, simultaneous ultrasonic and AEW treatments for 30 min led to 2.29 log CFU/mL reduction and thus, considered a synergistic effect. Flow cytometry combined with SYTO/PI staining analysis revealed that ultrasound hydrolyzed the cortex while the AEW partially damaged the integrity of the inner membrane. Scanning and transmission electron microscopies were used to characterize the ultrastructural changes. The detachment of the exosporium induced by ultrasound was the most apparent difference compared with the control group, and the electron density of spores appeared to be heterogeneous after treatment with AEW. These results indicated that combining ultrasound with AEW is a promising decontamination technology with potential uses in the food industry and environmental remediation.


Assuntos
Ácidos/farmacologia , Antibacterianos/farmacologia , Bacillus cereus/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Esporos Bacterianos/efeitos dos fármacos , Ondas Ultrassônicas , Água/química , Desinfetantes/farmacologia , Eletrólise , Indústria Alimentícia/métodos , Concentração de Íons de Hidrogênio , Água/farmacologia
10.
Ultrason Sonochem ; 64: 104992, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32018137

RESUMO

Thermosonication (TS) impacts numerous characteristics of spores, such as morphology, cell metabolism, and stress resistance. However, relevant mechanisms need to be clarified. In the present study, the effect of TS treatment on Bacillus subtilis spores was investigated at phenotypic and proteomic levels. The results showed that TS treatment induced significant changes to spores in growth kinetics and morphology. A total of 167 differentially expressed proteins (DEPs) were obtained after TS treatment at 6.67 W/mL and 80 °C. Among these proteins, 80 were up-regulated, whereas 87 were down-regulated. These DEPs were classed into 20 functional categories. Enrichment analysis of the proteome revealed that the major categories were associated with metabolic functions, including energy metabolic processes, amino acids biosynthesis and metabolism, translation and ribosomal protein. In summary, B. subtilis spores showed alteration primarily in the proteins that were associated with metabolism under TS treatment. These findings could be applied to the development and optimization of TS-based sporicidal treatment.


Assuntos
Bacillus subtilis/metabolismo , Proteômica , Sonicação , Esporos Bacterianos/metabolismo , Temperatura , Aminoácidos/metabolismo , Ribossomos/metabolismo
11.
J Food Prot ; 82(11): 1828-1836, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31596617

RESUMO

The impact of cold atmospheric pressure plasma treatment on the inactivation kinetics of Bacillus cereus ATCC 14579 and the resulting quality changes was investigated in tiger nut (Cyperus esculentus L.) milk (TNM). The effect of input power (39, 43, and 46 W) and treatment time (0 to 270 s) was fitted using the Weibull model to represent the microbial kinetic inactivation in the treated TNM. Inactivation efficacy increased with an increase in treatment time and input power. A 5.28-log reduction was achieved at 39 to 46 W without significant changes in titratable acidity, whereas no reduction in titratable acidity was observed in the pasteurized sample. The inactivation kinetics was adequately described by the Weibull model. Higher input power of 43 and 46 W and 120 s of treatment resulted in marked decreases in pH, flavonoid concentration, and antioxidant activity compared with those parameters in pasteurized TNM. Increases in total color difference and phenolic concentrations also were observed. The results indicate that these changes were caused by the immanent plasma reactive species. This study provides valuable inactivation kinetics information for food safety assessment studies of B. cereus vegetative cells in TNM.


Assuntos
Bacillus cereus , Microbiologia de Alimentos , Viabilidade Microbiana , Modelos Biológicos , Gases em Plasma , Pressão Atmosférica , Esporos Bacterianos
12.
Ultrason Sonochem ; 58: 104678, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31450348

RESUMO

This study investigated the effect of glycation on the binding of whey protein isolate (WPI) with (-)-epigallocatechin-3-gallate (EGCG), and the physicochemical stability and bioaccessibility of the formed complex. The WPI-gum Acacia (GA) conjugate was prepared by ultrasound-assisted Maillard reaction. Results indicated that conjugated WPI showed stronger binding and entrapping ability to EGCG than that of WPI. The protein aggregation induced by EGCG was partly inhibited by glycosylation, presumably due to the steric hindrance of polysaccharide chains. The greatest protection of EGCG and its antioxidant activity were also obtained by complexing it with WPI-GA conjugate. The in vitro bioaccessibility analysis demonstrated that the bioaccessibility of EGCG cloud be significantly (p < 0.05) enhanced by complexing it with WPI, especially WPI-GA conjugate. These findings are important to design promising and effective EGCG carriers for its wide application in food industry.


Assuntos
Catequina/análogos & derivados , Reação de Maillard , Ondas Ultrassônicas , Proteínas do Soro do Leite/química , Catequina/química , Glicosilação , Interações Hidrofóbicas e Hidrofílicas
13.
J Sci Food Agric ; 99(10): 4801-4807, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30977143

RESUMO

BACKGROUND: The functional properties of whey protein isolate (WPI) are sensitive to pH, ionic strength, and temperature. This prevents its application in various food systems and processing technologies. The conjugation of proteins with polysaccharides via the Maillard reaction is an efficient method to improve the functionality of proteins. The purpose of this work was to conjugate gum acacia (GA) with WPI via the dry-heating Maillard reaction and to investigate the effect of reaction time on the physicochemical and functional properties of WPI-GA conjugates. RESULTS: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance size exclusion chromatography confirmed the formation of higher molecular weight conjugates. The degrees of glycation for WPI-GA conjugates incubated for 1, 3, 5, and 7 days were 28.14%, 44.98%, 49.50%, and 51.20%, respectively. The glycation reaction reduced the surface hydrophobicity and fluorescence intensity of WPI significantly (P < 0.05). Functional properties of the conjugates, such as solubility, stability against heat-induced insolubility, and emulsion properties were all superior to the control WPI. However, a reaction time longer than a day resulted in a high degree of browning and decreased the functionality of the conjugate significantly (P < 0.05). CONCLUSION: The results indicated that conjugation of WPI with GA can be a promising way to enhance its functional properties. However, the reaction time suitable for producing conjugates with superior functional properties was not necessarily the highest glycation degree that could be reached. © 2019 Society of Chemical Industry.


Assuntos
Goma Arábica/química , Proteínas do Soro do Leite/química , Cromatografia em Gel , Cor , Eletroforese em Gel de Poliacrilamida , Emulsões/química , Glicosilação , Interações Hidrofóbicas e Hidrofílicas , Reação de Maillard , Peso Molecular , Concentração Osmolar , Solubilidade
14.
Appl Microbiol Biotechnol ; 103(5): 2329-2338, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30627794

RESUMO

Bacillus cereus spores are a concern to the food industry due to their high resistance to processing and their ability to germinate to vegetative cells under suitable conditions. This research aimed to elucidate the mechanisms of Bacillus cereus spore inactivation under ultrasonication (US) combined with thermal (thermosonication, TS) treatments, with pressure (manosonication, MS) treatments, and with thermal and pressure (manothermosonication, MTS) treatments. Electronic microscopy, dipicolinic acid (DPA) release, and flow cytometric assessments were used to investigate the inactivation effect and understand the inactivation mechanisms. The sporicidal effects of the US and thermal treatment were slight, and the MS and TS also showed little inactivation effect. However, ultrasonication promoted the detachment of the exosporium, thereby reducing the spore's ability to adhere to a surface, while the thermal treatment induced a decrease in the electron density in the nucleoid of bacterium, which retained a relatively intact exosporium and coat. MS caused 92.54% DPA release, which might be due to triggering of the germinant receptors or releasing of ions and Ca2+-DPA. In addition, the morphological changes such as core hydration and cortex degradation were significant after treatment with MS. The release of DPA and the morphological changes were responsible for the reduction in thermal resistance. The MTS showed a remarkable inactivation effect of 3.12 log CFU/mL reductions after 30 min of treatment. It was the most effective treatment and exhibited a large fraction of damage. In addition, the MTS had a significant impact on the intracellular structure of the spores, with the coat destroyed and the cortex damaged. These results indicated that ultrasonication combined with thermal and pressure treatments had a significant sporicidal effect on Bacillus cereus spores and could be a promising green sterilization technology.


Assuntos
Pressão Atmosférica , Bacillus cereus/crescimento & desenvolvimento , Temperatura Alta , Esporos Bacterianos/crescimento & desenvolvimento , Esterilização/métodos , Ondas Ultrassônicas , Contagem de Colônia Microbiana , Ácidos Picolínicos/metabolismo , Ultrassom/métodos
15.
RSC Adv ; 9(10): 5521-5529, 2019 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35515942

RESUMO

In this study, we modeled the water absorption, softening and shear viscosity change kinetics of canned rice porridge during cooking as well as estimated the thermodynamic properties involved in hydration. Moreover, the internal microstructure of rice kernels was observed under different hydrothermal conditions. During cooking, the water absorption and shear viscosity alteration rate increased with temperature, whereas the softening rate decreased. However, the temperature did not significantly affect the equilibrium value of the physical properties. The variation tendencies of the moisture content and hardness of the kernels could be expressed satisfactorily by the exponential and the generalized exponential models. The porridge shear viscosity variations fitted the sigmoidal and its generalized models. Thermodynamic parameters (enthalpy, entropy and Gibbs free energy) revealed that the hydration process was non-spontaneous and exothermic. Furthermore, scanning electron microscopy images and the results of the X-ray diffraction analysis showed the microstructure of the kernels during cooking, and the kernels formed a homogeneous mesh structure at earlier times during the initial stage at higher temperatures. These findings would provide valuable information for the optimization of canned rice porridge production.

16.
Front Microbiol ; 10: 2920, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31998253

RESUMO

Campylobacter can enter a viable but non-culturable (VBNC) state to evade various stresses, and this state is undetectable using traditional microbiological culturing techniques. These VBNC bacterial cells retain metabolism and demonstrate pathogenic potential due to their ability to resuscitate under favorable conditions. Rapid and accurate determination of VBNC Campylobacter is critical to further understand the induction and resuscitation of the dormancy state of this microbe in the agri-food system. Here, we integrated propidium monoazide (PMA) with real-time polymerase chain reaction (qPCR) targeting the rpoB gene to detect and quantify Campylobacter jejuni in the VBNC state. First, we optimized the concentration of PMA (20 µM) that could significantly inhibit the amplification of dead cells by qPCR with no significant interference on the amplification of viable cell DNA. PMA-qPCR was highly specific to C. jejuni with a limit of detection (LOD) of 2.43 log CFU/ml in pure bacterial culture. A standard curve for C. jejuni cell concentrations was established with the correlation coefficient of 0.9999 at the linear range of 3.43 to 8.43 log CFU/ml. Induction of C. jejuni into the VBNC state by osmotic stress (i.e., 7% NaCl) was rapid (<48 h) and effective (>10% population). The LOD of PMA-qPCR for VBNC C. jejuni exogenously applied to chicken breasts was 3.12 log CFU/g. In conclusion, PMA-qPCR is a rapid, specific, and sensitive method for the detection and quantification of VBNC C. jejuni in poultry products. This technique can give insight into the prevalence of VBNC Campylobacter in the environment and agri-food production system.

17.
J Food Sci ; 84(1): 111-120, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30548488

RESUMO

Although different delivery systems have been developed to overcome the limits of Epigallocatechin-3-gallate (EGCG) and quercetin in food application, none have referred to their simultaneous encapsulation. In this study, these two polyphenols were successfully co-loaded into liposomes. Under the optimal conditions (lecithin-total polyphenols ratio 25:1, lecithin-cholesterol ratio 6:1, lecithin-Tween 80 ratio 8:1 and ultrasonic time 2 min), the mean size, polydispersity index (PDI) and zeta potential of liposomes were 111.10 ± 0.52 nm, 0.259 ± 0.006 and -19.83 ± 0.45 mV, with an encapsulation efficiency of 64.05 ± 1.56% and 61.73 ± 2.55% for EGCG and quercetin, respectively. After 30-day storage, an increase of 4.05% was observed in the mean size with no significant change (P ≥ 0.05) in the PDI and zeta potential. Moreover, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed a synergistic antioxidant effect of the two compounds in liposomal system. These results demonstrated that co-encapsulation of EGCG and quercetin enhances their effectiveness. PRACTICAL APPLICATION: EGCG and quercetin are natural polyphenols abound in the human diet with diverse biological activities. These two polyphenols were successfully co-encapsulated into a homogeneous and stable liposomal system. Interestingly, a synergistic antioxidant effect of the two polyphenols was observed due to co-encapsulation. This indicated that the simultaneous delivery of EGCG and quercetin was an attractive approach to improve their functionality for expanding their application in food, cosmetic and pharmaceutical industries.


Assuntos
Catequina/análogos & derivados , Manipulação de Alimentos , Lipossomos/química , Quercetina/química , Antioxidantes/química , Catequina/química , Lecitinas/química , Microscopia Eletrônica de Transmissão , Tamanho da Partícula
18.
Food Chem ; 274: 234-241, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30372932

RESUMO

Effect of pH-shifting on structural and functional properties of whey protein isolate and its interaction with (-)-epigallocatechin-3-gallate were investigated. Circular dichroism spectra showed that pH-shifting induced the decrease in α-helix content by 12.18% and ß-sheet content by 3.24%, but ß-turn and random coil content increased by 4.26% and 5.91%, respectively. Increase of fluorescence intensity and red-shift of maximum emission wavelength indicated the structural unfolding and exposure of tyrosine. The treatment also significantly increased the surface hydrophobicity, disulfide bonds content, solubility, emulsifying activity and emulsion stability of whey protein isolate at P < 0.05 level. Fluorescence quenching analysis revealed that treated whey protein isolate have a stronger binding affinity to (-)-epigallocatechin-3-gallate, resulting a better protection against the degradation of (-)-epigallocatechin-3-gallate and its antioxidant activity. This study confirmed that pH-shifting treatment can improve functional properties of whey protein isolate and its potential as a protective carrier for polyphones.


Assuntos
Catequina/análogos & derivados , Proteínas do Soro do Leite/química , Catequina/química , Catequina/metabolismo , Dicroísmo Circular , Emulsões/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Secundária de Proteína , Solubilidade , Espectrometria de Fluorescência , Triptofano/química , Proteínas do Soro do Leite/metabolismo
19.
Sheng Li Xue Bao ; 68(3): 249-54, 2016 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-27350197

RESUMO

The aim of this study was to investigate the relationship between the acetylcholine concentration in the blood and gelsenicine-induced death in mice. Kunming mice were given intraperitoneal injections of normal saline, gelsenicine or different doses of acetylcholine chloride. Atropine was given to the mice which received gelsenicine or medium dose acetylcholine chloride injection. The blood was sampled immediately when the mice died or survived for 20 min after injection. The acetylcholine concentration and acetylcholinesterase activity in the blood were measured by the testing kits, and the mortality was calculated and analyzed. The results showed that half lethal dose of gelsenicine (0.15 mg/kg) reduced the acetylcholinesterase activity and increased the blood acetylcholine concentration. The blood acetylcholine concentration of the dead mice in the gelsenicine group was increased to 43.0 µg/mL (from 31.1 µg/mL in the control), which was lower than that (53.9 µg/mL) of the dead mice in the medium dose acetylcholine chloride group, but almost equal to that (42.7 µg/mL) of the survival mice in the medium dose acetylcholine chloride group. Atropine could successfully rescue the mice from acetylcholine poisoning, but its efficiency of rescuing the mice from gelsenicine intoxication was weak. These results suggest that gelsenicine can inhibit acetylcholinesterase activity and increase blood acetylcholine concentration, but the accumulation of acetylcholine may not be the only or main cause of the death induced by gelsenicine in mice.


Assuntos
Morte , Acetilcolina , Animais , Alcaloides Indólicos , Camundongos
20.
Int J Biol Macromol ; 72: 924-30, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25451747

RESUMO

Sulfated polysaccharide (UFP(31)) extracted from the marine algae Ulva fasciata (UFP) was a heteropolysaccharide, and consisted of rhamnose, xylose, and glucose in a ratio of 1:0.46:0.27 with a (1 → 4)-linked glycosyl backbone. The rheology of UFP(31) solution has been investigated by steady shear and small amplitude oscillatory experiments. The effects of concentration, temperature, and time were systematically investigated. Steady-shear rheological measurement in a range of shear rate (1-1000 s(-1)) exhibited that UFP(31) has a Newtonian behavior in diluted solutions (1.0%, 3.0%, and 5.0%, w/v), dilatant flow behavior at higher concentrations (7.0% and 9.0%, w/v). Specifically, UFP(31) solution (7%, w/v) exhibited antithixotropic behavior. In small amplitude oscillatory experiments, both the storage modulus (G') and the loss modulus (G") of UFP(31) solution (7%, w/v) increased with frequency swept but G' increased more quickly. As a consequence, G' tends to overcome G" at 2.7 Hz. The capability of moisture-absorption and moisture-retention of the polysaccharide was also respectively examined gravimetrically in comparison with those of glycerol. It revealed that UFP(31) exhibited a higher ability both in the moisture-absorption and moisture-retention test throughout the entire experiment. These results clearly establish the possibility that UFP(31) could be employed as a new material of nature moisturizer.


Assuntos
Polissacarídeos/química , Ulva/química , Água/química , Glucose/química , Glicerol/química , Polissacarídeos/isolamento & purificação , Ramnose/química , Reologia , Sulfatos/química , Viscosidade , Xilose/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA