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1.
J Food Sci ; 86(3): 667-676, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33496977

RESUMO

This study analyzed a new drying method using airborne ultrasound combined with microwave vacuum to study its effect on the quality characteristics and microstructure of dehydrated L. edodes. Ultrasonic treatment resulted in many micropores in the product, forming the sponge effect caused by ultrasonic waves, which can promote the rapid evaporation of water in the product. Samples of Lentinula edodes individuals were dried using four methods: hot air drying (HAD), microwave vacuum drying (MVD), microwave vacuum drying after ultrasonic pretreatment (US+MVD) and airborne ultrasonic treatment combined with microwave vacuum drying (USMVD). The results showed that USMVD can reduced the loss of total sugar, total phenol, and total antioxidants in L. edodes, and increased the relative content of ergosterol, sulfur compounds, and free amino acids (p < 0.05). Scanning electron microscope observation revealed that USMVD resulted in a uniform reticular porous structure, which could better maintain desirable levels of nutrients. Therefore, USMVD can produce high quality products. PRACTICAL APPLICATION: Airborne ultrasonic waves combined with MVD provides an innovative drying method for mushrooms, which has not been studied at present. The mixed drying method has great potential in maintaining product quality. It provides a theoretical basis for studying drying technology in the future.


Assuntos
Dessecação/métodos , Micro-Ondas , Cogumelos Shiitake/química , Ultrassom , Antioxidantes/química , Manipulação de Alimentos , Cogumelos Shiitake/ultraestrutura , Temperatura , Vácuo , Água
2.
Food Chem ; 305: 125470, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31610423

RESUMO

The thermo-oxidative behavior crucial to the applicability of ethylcellulose (EC) oleogels is characterized. Not only did we take into account the composition of the gel network in relation to textural attributes, but also the dynamic chemical changes occurred during formation, heating, and holding of the gels. EC oleogel oxidative stability showed that at 6.0% EC100 concentration in the oleogels the movement of liquid oil trapped in the gel network was hindered by its high viscosity and stable gel network, thus retarding oxidation. Processing temperature ≤ 120 °C for <2 h was recommended when incorporated in food systems to minimize oxidation. As for the measurement of oxidative stability in general, p-AnV was found suitable in depicting oxidation of EC oleogels. Meanwhile, both Rao and Rad acquired from 1H NMR spectra could serve as reliable oxidative indicators to gauge total oxidation of EC oleogels during storage.


Assuntos
Celulose/análogos & derivados , Celulose/química , Espectroscopia de Ressonância Magnética , Compostos Orgânicos/química , Oxirredução , Reologia , Temperatura de Transição , Viscosidade
3.
J Agric Food Chem ; 67(27): 7684-7693, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31203623

RESUMO

This study investigated the alleviative effect of caffeic acid (CA) on Alzheimer's disease (AD) pathogenesis and associated mechanisms in high-fat (HF) diet-induced hyperinsulinemic rats. The results of a Morris water maze indicated that, by administrating CA (30 mg/kg b.w./day) for 30 weeks, the memory and learning impairments in HF-induced hyperinsulinemic rats were significantly ameliorated. CA also enhanced superoxide dismutase and glutathione free radical scavenger activity in hyperinsulinemic rats. The Western blot data further confirmed that protein expressions of phosphorylated-glycogen synthase kinase 3ß (GSK3ß) were significantly increased, whereas the expression of phosphorylated-tau protein decreased in the hippocampus of rats administered with CA in comparison with the HF group. Moreover, the expression of amyloid precursor protein (APP) and ß-site APP cleaving enzyme were attenuated, subsequently lowering the level of ß-amyloid 1-42 (Aß 1-42) in the hippocampus of CA-treated hyperinsulinemic rats. CA also significantly increased the expression of synaptic proteins in HF rats.


Assuntos
Doença de Alzheimer/prevenção & controle , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Ácidos Cafeicos/administração & dosagem , Insulina/metabolismo , Plasticidade Neuronal/efeitos dos fármacos , Doença de Alzheimer/metabolismo , Animais , Antioxidantes/química , Córtex Cerebral/química , Córtex Cerebral/enzimologia , Córtex Cerebral/metabolismo , Dieta Hiperlipídica , Modelos Animais de Doenças , Glutationa/metabolismo , Glicogênio Sintase Quinase 3 beta/análise , Glicogênio Sintase Quinase 3 beta/metabolismo , Hipocampo/química , Hipocampo/enzimologia , Hipocampo/metabolismo , Hiperinsulinismo/etiologia , Hiperinsulinismo/metabolismo , Masculino , Fosforilação , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Proteínas tau/análise , Proteínas tau/metabolismo
4.
J Food Sci ; 84(6): 1456-1464, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31107551

RESUMO

A novel shortening was developed based on oleogels structured by ethylcellulose (EC) polymers. The texture and oil retention ability of EC oleogels were characterized against the level of viscosity of different grades of EC, as well as the rheological properties in relation to the polymer structure in the gel network. EC100, which has an average viscosity of 100 cP, was selected as the most suitable organogelator at 4% (w/w) in combination with base oil (30% degree of saturation by mixing palm stearin and soybean oil) to form the shortening. Triglyceryl monostearate (TMS) was found to be the most effective emulsifier as evidenced by its ability to strengthen air-incorporation ability of the shortening while creating evenly distributed fine crystals in the system. The EC100 shortening was able to create breads with excellent specific volume, indicating its ability to incorporate air bubbles during dough development and to serve as an antifirming agent to create bread with stable soft texture. PRACTICAL APPLICATION: In the present study, we attempted to create a novel shortening by employing oleogels structured by ethylcellulose (EC), the most promising gelation agent to develop gel network capable of replacing solid fat without health concerns. EC oleogels in shortening with detailed characterization of the shortening microstructure in relation to its functional properties was elucidated. The optimal formulation in relation to preservation of gel structure and consistency with enhanced moisture and air retention were also identified.


Assuntos
Celulose/análogos & derivados , Gorduras na Dieta/análise , Pão/análise , Celulose/química , Culinária/métodos , Emulsificantes , Géis/química , Glicerídeos/química , Compostos Orgânicos/química , Óleo de Palmeira/química , Polímeros/química , Reologia , Óleo de Soja/química , Viscosidade
5.
J Agric Food Chem ; 65(45): 9893-9901, 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29058433

RESUMO

Although nanosized ingredients, including TiO2 nanoparticles (NPs), can be found in a wide range of consumer products, little is known about the effects these particles have on other active compounds in product matrices. These NPs can interact with reactive oxygen species (ROS), potentially disrupting or canceling the benefits expected from antioxidants. We used electron spin resonance spectrometry to assess changes in the antioxidant capacities of six dietary antioxidants (ascorbic acid, α-tocopherol, glutathione, cysteine, epicatechin, and epicatechin gallate) during exposure to P25 TiO2 and/or simulated sunlight. Specifically, we determined the ability of these antioxidants to scavenge 1-diphenyl-2-picryl-hydrazyl radical, superoxide radical, and hydroxyl radical. Exposure to simulated sunlight alone did not lead to noticeable changes in radical-scavenging abilities; however, in combination with P25 TiO2 NPs, the scavenging abilities of most antioxidants were weakened. We found glutathione to be the most resistant to treatment with sunlight and NPs among these six antioxidants.


Assuntos
Sequestradores de Radicais Livres/química , Radicais Livres/química , Nanopartículas/química , Titânio/química , Sequestradores de Radicais Livres/efeitos da radiação , Nanopartículas/efeitos da radiação , Luz Solar , Titânio/efeitos da radiação
6.
J Dairy Res ; 82(4): 506-12, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26234882

RESUMO

The ultimate goal of this work was to examine the effect of xanthan-curdlan hydrogel complex (XCHC) on the rheology of whey protein isolate (WPI) within the pH range of 4-7 upon heating and cooling. Dynamic rheological properties of WPI and XCHC were studied individually and in combination, as a function of time or temperature. For pure WPI, gels were pH-dependent, and in all pH values except 7, gels formed upon first heating from 40 to 90 °C. At pH 7, WPI did not form gel upon first heating, and the storage modulus (G') started to increase during the holding time at 90 °C. The onset of gelation temperature of WPI was lower in acidic pH ranges compared to the neutral pH. In mixed gels, the presence of XCHC increased the G' of the gels. The rheological behaviour was pH-dependent and initially was controlled by XCHC; however, after the consolidation of WPI network, the behaviour was led by the whey protein isolate. Results showed that XCHC had a synergistic effect on enhancing the elastic modulus of the gels after the consolidation of WPI network. Based on the results of this study, it is possible to use these biopolymers in the formulation of frozen dairy-based products and enable food manufactures to improve the textural and physicochemical properties, and as a result the consumer acceptance of the food product.


Assuntos
Géis/química , Polissacarídeos Bacterianos/química , Reologia , Proteínas do Soro do Leite/química , beta-Glucanas/química , Concentração de Íons de Hidrogênio , Teste de Materiais , Temperatura
7.
J Food Sci ; 80(7): E1498-505, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26012512

RESUMO

UNLABELLED: The effect of adding xanthan-curdlan hydrogel complex (XCHC) at 2 concentrations (0.25 and 0.5% w/w) on the freeze-thaw stability of heat-induced whey protein isolate (WPI) gel was investigated. Samples were stored at 4 °C for 24 h before subjected to 5 freeze-thaw cycles alternating between -16 °C (18 h) and 25 °C (6 h). Adding XCHC to the WPI solution resulted in the reduction of a significant amount of syneresis up to 5 repeated freeze-thaw cycles. Addition of XCHC decreased the amount of syneresis from 45% in the control sample (pure WPI gel) to 31.82% and 5.44% in the samples containing 0.25% and 0.5% gum, respectively, after the 5th freeze-thaw cycle. XCHC increased the storage modulus (G') of the gels and minimized the changes of the G' values over the 5 freeze-thaw cycles, indicating improvement of the stability of the system. Furthermore, the minimum protein concentration for gel formation decreased in the presence of the XCHC. Scanning electron microscopy (SEM) images showed that addition of XCHC resulted in the formation of a well-structured gel with numerous small pores in the network, which consequently improved the water retention ability during the temperature abuses up to 5 freeze-thaw cycles. These results have important implications for using XCHC in the formulation of the frozen WPI-based products with improved freeze-thaw stability and rheological properties. PRACTICAL APPLICATION: Application of XCHC in the formulation of frozen dairy-based food products has the potential to enhance freeze-thaw stability and minimize moisture migration caused by temperature abuses of the products during distribution and consumer application.


Assuntos
Congelamento , Hidrogéis/química , Polissacarídeos Bacterianos/química , Reologia , Proteínas do Soro do Leite/química , beta-Glucanas/química , Manipulação de Alimentos , Alimentos Congelados , Microscopia Eletrônica de Varredura , Temperatura
8.
Nanoscale ; 7(10): 4505-13, 2015 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-25684572

RESUMO

Molecules with diverse biological functions, such as heme peroxidases, can be useful tools for identifying potential biological effects of gold nanoparticles (AuNPs) at the molecular level. Here, using UV-Vis, circular dichroism, dynamic light scattering, and electron spin resonance spectroscopy, we report tuning of horseradish peroxidase (HRP) bioactivity by reactant-free AuNPs with diameters of 5, 10, 15, 30 and 60 nm (Au-5 nm, Au-10 nm, Au-15 nm, Au-30 nm and Au-60 nm). HRP conjugation to AuNPs was observed with only Au-5 nm and Au-10 nm prominently increasing the α-helicity of the enzyme to extents inversely related to their size. Au-5 nm inhibited both HRP peroxidase activity toward 3,3',5,5'-tetramethylbenzidine and HRP compound I/II reactivity toward 5,5-dimethyl-1-pyrroline N-oxide. Au-5 nm enhanced the HRP peroxidase activity toward ascorbic acid and the HRP compound I/II reactivity toward redox-active residues in the HRP protein moiety. Further, Au-5 nm also decreased the catalase- and oxidase-like activities of HRP. Au-10 nm showed similar, but weaker effects, while Au-15 nm, Au-30 nm and Au-60 nm had no effect. Results suggest that AuNPs can size-dependently enhance or inhibit HRP bioreactivity toward substrates with different redox potentials via a mechanism involving extension of the HRP substrate access channel and decline in the redox potentials of HRP catalytic intermediates.


Assuntos
Ácido Ascórbico/química , Ouro/química , Nanopartículas Metálicas/química , Peroxidase do Rábano Silvestre/química , Oxirredução , Tamanho da Partícula
9.
J Food Prot ; 78(1): 121-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25581186

RESUMO

Biofilm-forming bacteria resident to food processing facilities are a food safety concern due to the potential of biofilms to harbor foodborne bacterial pathogens. When cultured together, Ralstonia insidiosa, a strong biofilm former frequently isolated from produce processing environments, has been shown to promote the incorporation of Escherichia coli O157:H7 into dual-species biofilms. In this study, interactions between E. coli O157:H7 and R. insidiosa were examined under different incubating conditions. Under static culture conditions, the incorporation of E. coli O157:H7 into biofilms with R. insidiosa was not significantly affected by either low incubating temperature (10°C) or by limited nutrient availability. Greater enhancement of E. coli O157:H7 incorporation in dual-species biofilms was observed by using a continuous culture system with limited nutrient availability. Under the continuous culture conditions used in this study, E coli O157:H7 cells showed a strong tendency of colocalizing with R. insidiosa on a glass surface at the early stage of biofilm formation. As the biofilms matured, E coli O157:H7 cells were mostly found at the bottom layer of the dual-species biofilms, suggesting an effective protection by R. insidiosa in the mature biofilms.


Assuntos
Biofilmes/crescimento & desenvolvimento , Escherichia coli O157/fisiologia , Ralstonia/fisiologia , Carga Bacteriana , Meio Ambiente , Manipulação de Alimentos , Microbiologia de Alimentos , Temperatura
10.
J Agric Food Chem ; 62(49): 12052-60, 2014 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-25393426

RESUMO

When exposed to light, TiO2 nanoparticles (NPs) become photoactivated and create electron/hole pairs as well as reactive oxygen species (ROS). We examined the ROS production and degradation of a widely used azo dye, FD&C Yellow No. 5 (tartrazine), triggered by photoactivated TiO2 NPs. Degradation was found to follow pseudo-first order reaction kinetics where the rate constant increased with TiO2 NP concentration. Depositing Au on the surface of TiO2 largely enhanced electron transfer and ROS generation, which consequently accelerated dye degradation. Alkaline conditions promoted ROS generation and dye degradation. Results from electron spin resonance spin-trap spectroscopy suggested that at pH 7.4, both hydroxyl radical (•OH) and singlet oxygen ((1)O2) were responsible for dye discoloration, whereas at pH 5, the consumption of (1)O2 became dominant. Implications for dye degradation in foods and other consumer products that contain both TiO2 and FD&C Yellow No. 5 as ingredients are discussed.


Assuntos
Corantes/química , Nanopartículas/química , Fotólise/efeitos da radiação , Espécies Reativas de Oxigênio/química , Tartrazina/química , Ouro/química , Cinética , Luz Solar , Titânio/química
11.
J Food Sci ; 79(10): R1861-70, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25224872

RESUMO

Low-moisture foods have been responsible for a number of salmonellosis outbreaks worldwide over the last few decades, with cross contamination from contaminated equipment being the most predominant source. To date, actions have been focused on stringent hygienic practices prior to production, namely periodical sanitization of the processing equipment and lines. Not only does optimum sanitization require in-depth knowledge on the type and source of contaminants, but also the heat resistance of microorganisms is unique and often dependent on the heat transfer characteristics of the low-moisture foods. Rheological properties, including viscosity, degree of turbulence, and flow characteristics (for example, Newtonian or non-Newtonian) of both liquid and semisolid foods are critical factors impacting the flow behavior that consequently interferes heat transfer and related control elements. The demand for progressively more accurate prediction of complex fluid phenomena has called for the employment of computational fluid dynamics (CFD) to model mass and heat transfer during processing of various food products, ranging from drying to baking. With the aim of improving the quality and safety of low-moisture foods, this article critically reviewed the published literature concerning microbial survival in semisolid low-moisture foods, including chocolate, honey, and peanut butter. Critical rheological properties and state-of-the-art CFD application relevant to quality production of those products were also addressed. It is anticipated that adequate prediction of specific transport properties during optimum sanitization through CFD could be used to solve current and future food safety challenges.


Assuntos
Análise de Alimentos , Microbiologia de Alimentos , Qualidade dos Alimentos , Salmonella/fisiologia , Água/química , Salmonella/isolamento & purificação
12.
J Agric Food Chem ; 62(34): 8632-9, 2014 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-25074419

RESUMO

The mechanisms by which meat enhances human absorption of non-heme iron remain unknown. Recently, anchovy (Engraulis japonicus) muscle protein hydrolysate (AMPH) was found to mediate the formation of nanosized ferric hydrolysis products in vitro. The current paper evaluates the effects of AMPH on the bioavailability and the intestinal speciation of non-heme iron in rats, followed by an investigation of cellular uptake pathways of in vitro-formed AMPH-stabilized nanosized ferric hydrolysis products (ANPs) by polarized human intestinal epithelial (Caco-2) cells. The hemoglobin regeneration efficiencies in anemic rats followed the order ferric citrate (9.79 ± 2.02%) < commercial bare α-Fe2O3 nanoparticles (16.37 ± 6.65%) < mixture of ferric citrate and AMPH (40.33 ± 6.36%) ≈ ferrous sulfate (40.88 ± 7.67%) < ANPs (56.25 ± 11.35%). Percentage contents of intestinal low-molecular-weight iron in the groups of FC+AMPH, FeSO4, and ANPs were significantly lower than the corresponding hemoglobin regeneration efficiencies (P < 0.05), providing strong evidence for the involvement of nanosized iron in intestinal iron absorption from FC+AMPH, FeSO4, and ANPs. Calcein-fluorescence measurements of the labile iron pool of polarized Caco-2 cells revealed the involvement of both divalent transporter 1 and endocytosis in apical uptake of ANPs, with endocytosis dominating at acidic extracellular pH. Overall, AMPH enhancement of non-heme iron absorption involves a nanoparticle-mediated mechanism.


Assuntos
Anemia/metabolismo , Proteínas de Peixes/metabolismo , Absorção Intestinal , Mucosa Intestinal/metabolismo , Ferro/metabolismo , Alimentos Marinhos/análise , Anemia/dietoterapia , Anemia/fisiopatologia , Animais , Disponibilidade Biológica , Células CACO-2 , Feminino , Proteínas de Peixes/química , Peixes , Humanos , Hidrólise , Intestinos/fisiopatologia , Ferro/química , Masculino , Nanopartículas/química , Nanopartículas/metabolismo , Ratos
13.
J Food Drug Anal ; 22(1): 86-94, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24673906

RESUMO

Nano-iron metal and nano-iron oxides are among the most widely used engineered and naturally occurring nanostructures, and the increasing incidence of biological exposure to these nanostructures has raised concerns about their biotoxicity. Reactive oxygen species (ROS)-induced oxidative stress is one of the most accepted toxic mechanisms and, in the past decades, considerable efforts have been made to investigate the ROS-related activities of iron nanostructures. In this review, we summarize activities of nano-iron metal and nano-iron oxides in ROS-related redox processes, addressing in detail the known homogeneous and heterogeneous redox mechanisms involved in these processes, intrinsic ROS-related properties of iron nanostructures (chemical composition, particle size, and crystalline phase), and ROS-related bio-microenvironmental factors, including physiological pH and buffers, biogenic reducing agents, and other organic substances.


Assuntos
Compostos Férricos , Ferro , Nanopartículas Metálicas/toxicidade , Espécies Reativas de Oxigênio/metabolismo , Animais , Microambiente Celular , Compostos Férricos/química , Humanos , Ferro/química , Nanopartículas Metálicas/química , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/química
14.
J Food Drug Anal ; 22(1): 76-85, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24673905

RESUMO

Titanium dioxide nanoparticles (TiO(2) NPs) are one of the most widely used nanomaterials that have been manufactured worldwide and applied in different commercial realms. The well-recognized ability of TiO(2) to promote the formation of reactive oxygen species (ROS) has been extensively studied as one of the important mechanisms underlying TiO(2) NPs toxicity. As the "gold standard" method to quantify and identify ROS, electron spin resonance (ESR) spectroscopy has been employed in many studies aimed at evaluating TiO(2) NPs safety. This review aims to provide a thorough discussion of current studies using ESR as the primary method to unravel the mechanism of TiO(2) NPs toxicity. ESR spin label oximetry and immune-spin trapping techniques are also briefly introduced, because the combination of spin trapping/labeling techniques offers a promising tool for studying the oxidative damage caused by TiO(2) NPs.


Assuntos
Espectroscopia de Ressonância de Spin Eletrônica , Nanopartículas Metálicas/toxicidade , Titânio , Animais , Dano ao DNA , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Humanos , Nanopartículas Metálicas/química , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Titânio/química
15.
Int J Food Microbiol ; 171: 15-20, 2014 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-24296258

RESUMO

Biofilm formation is a mechanism adapted by many microorganisms that enhances the survival in stressful environments. In food processing facilities, foodborne bacterial pathogens, which many are poor biofilm formers, could potentially take advantage of this protective mechanism by interacting with other strong biofilm producers. The objective of this study was to determine the influence of bacteria native to fresh produce processing environments on the incorporation of Escherichia coli O157:H7 in biofilms. Bacteria strains representing 13 Gram-negative species isolated from two fresh produce processing facilities in a previous study were tested for forming dual-species biofilms with E. coli O157:H7. Strong biofilm producing strains of Burkholderia caryophylli and Ralstonia insidiosa exhibited 180% and 63% increase in biofilm biomass, and significant thickening of the biofilms (B. caryophylli not tested), when co-cultured with E. coli O157:H7. E. coli O157:H7 populations increased by approximately 1 log in dual-species biofilms formed with B. caryophylli or R. insidiosa. While only a subset of environmental isolates with strong biofilm formation abilities increased the presence of E. coli O157:H7 in biofilms, all tested E. coli O157:H7 exhibited higher incorporation in dual-species biofilms with R. insidiosa. These observations support the notion that E. coli O157:H7 and specific strong biofilm producing bacteria interact synergistically in biofilm formation, and suggest a route for increased survival potential of E. coli O157:H7 in fresh produce processing environments.


Assuntos
Biofilmes , Escherichia coli O157/fisiologia , Microbiologia de Alimentos , Bactérias Gram-Negativas/fisiologia , Aderência Bacteriana , Contagem de Colônia Microbiana , Escherichia coli O157/isolamento & purificação , Bactérias Gram-Negativas/isolamento & purificação
16.
J Agric Food Chem ; 61(32): 7855-62, 2013 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-23889173

RESUMO

The use of nanomaterials in consumer products is rapidly expanding. In most studies, nanomaterials are examined as isolated ingredients. However, consumer products such as foods, cosmetics, and dietary supplements are complex chemical matrixes. Therefore, interactions between nanomaterials and other components of the product must be investigated to ensure the product's performance and safety. Silver nanomaterials are increasingly being used in food packaging as antimicrobial agents. Thiol-containing compounds, such as reduced glutathione (GSH), cysteine, and dihydrolipoic acid, are used as antioxidants in many consumer products. In the current study, we have investigated the interaction between silver nanomaterials and thiol-containing antioxidants. The selected Ag nanomaterials were Ag coated with citrate, Ag coated with poly(vinylpyrrolidone), and Au nanorods coated with Ag in a core/shell structure. We observed direct quenching of the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) by all three Ag nanomaterials to varying degrees. The Ag nanomaterials also reduced the quenching of DPPH by GSH to varying degrees. In addition, we determined that the mixture of GSH and Au@Ag nanorods held at 37 °C was less effective at quenching azo radical than at ambient temperature. Furthermore, we determined that Au@Ag nanorods significantly reduced the ability of GSH and cysteine to quench hydroxyl and superoxide radicals. The work presented here demonstrates the importance of examining the chemical interactions between nanomaterials used in products and physiologically important antioxidants.


Assuntos
Antioxidantes/química , Nanoestruturas/química , Prata/química , Compostos de Sulfidrila/química
17.
J Food Prot ; 76(5): 827-32, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23643124

RESUMO

Representative food contact and nonfood contact surfaces in two mid-sized, fresh-cut processing facilities were sampled for microbiological analyses after routine daily sanitization. Mesophilic and psychrotrophic bacteria on the sampled surfaces were isolated by plating on nonselective bacterial media. Alternatively, bacteria were isolated after an incubation period that allowed the formation of heterogeneous biofilms on stainless steel beads. Of over 1,000 tested isolates, most were capable of forming biofilms, with approximately 30 % being strong or moderate biofilm formers. Selected isolates (117) were subjected to species identification by using the Biolog Gen III microbial identification system. They distributed among 23 genera, which included soil bacteria, plant-related bacteria, coliforms, and opportunistic plant- or human-pathogenic bacteria. The most commonly identified bacteria species were Pseudomonas fluorescens, Rahnella aquatilis, and Ralstonia insidiosa. The high prevalence of R. insidiosa, a strong biofilm former, and P. fluorescens, a moderate biofilm former, suggests that they were established residents in the sampled plants. These results suggest that native microflora capable of forming biofilms are widely distributed in fresh-produce processing environments.


Assuntos
Aderência Bacteriana/fisiologia , Fenômenos Fisiológicos Bacterianos , Microbiologia Ambiental , Manipulação de Alimentos/métodos , Indústria de Processamento de Alimentos , Bactérias/isolamento & purificação , Biofilmes/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Frutas/microbiologia , Humanos , Pseudomonas fluorescens/isolamento & purificação , Pseudomonas fluorescens/fisiologia , Aço Inoxidável , Verduras/microbiologia
18.
Carbohydr Polym ; 92(2): 1159-65, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-23399141

RESUMO

Oat ß-glucan was purified from oat bran and its effects on running performance and related biochemical parameters were investigated. Four-week-old male Sparsgue-Dawley rats, fed with/without oat ß-glucan (312.5 mg kg(-1) d(-1)) for 7 weeks, were subjected to run on a treadmill system to make them exhausted. All rats were immediately sacrificed after prolonged exercise, and the major metabolic substrates were measured in serum and liver. The results showed feeding dietary oat ß-glucan to rats could significantly reduce the body weight and increase the maximum running time compared with normal control (P<0.05). Furthermore, dietary oat ß-glucan decreased the levels of blood urea nitrogen, lactate acid, and creatine kinase activity in serum, and increased the levels of non-esterified fatty acids, lactic dehydrogenase activity in serum, and the content of liver glycogen. Therefore, the present study demonstrated that dietary oat ß-glucan can enhance the endurance capacity of rats while facilitating their recovery from fatigue.


Assuntos
Avena/química , Fadiga/tratamento farmacológico , Condicionamento Físico Animal , Resistência Física/efeitos dos fármacos , beta-Glucanas/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Nitrogênio da Ureia Sanguínea , Peso Corporal/efeitos dos fármacos , Fenômenos Químicos , Creatina Quinase/metabolismo , Ingestão de Alimentos/efeitos dos fármacos , Teste de Esforço , Fadiga/sangue , Fadiga/metabolismo , Fadiga/fisiopatologia , Ácidos Graxos não Esterificados/sangue , Glicogênio/metabolismo , L-Lactato Desidrogenase/metabolismo , Ácido Láctico/sangue , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Ratos , Ratos Sprague-Dawley , Corrida/fisiologia , beta-Glucanas/uso terapêutico
19.
Nanoscale ; 5(4): 1583-91, 2013 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-23329011

RESUMO

Au@Pt nanorods were prepared by growing platinum nanodots on gold nanorods. Using electron spin resonance (ESR), we determined that the mechanisms for oxidation of ascorbic acid (AA) by Au@Pt nanorods and ascorbic acid oxidase (AAO) were kinetically similar and yielded similar products. In addition we observed that Au@Pt nanorods were stable with respect to temperature and pH. Using UV-VIS spectroscopy, the apparent kinetics of enzyme-mimetic activity of Au@Pt nanorods were studied and compared with the activity of AAO. With the help of ESR, we found that Au@Pt nanorods did not scavenge hydroxyl radicals but inhibited the antioxidant ability of AA for scavenging hydroxyl radicals produced by photoirradiating solutions containing titanium dioxide and zinc oxide. Moreover, the Au@Pt nanorods reduced the ability of AA to scavenge DPPH radicals and superoxide radicals. These results demonstrate that Au@Pt nanorods can reduce the antioxidant activity of AA. Therefore, it is necessary to consider the effects of using Pt nanoparticles together with other reducing agents or antioxidants such as AA due to the oxidase-like property of Au@Pt nanorods.


Assuntos
Antioxidantes/química , Ácido Ascórbico/química , Ouro/química , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Platina/química , Ativação Enzimática , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Oxirredutases/química , Tamanho da Partícula , Propriedades de Superfície
20.
Foodborne Pathog Dis ; 10(1): 87-96, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23256843

RESUMO

Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce-wash, the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce pieces were inoculated with a five-strain cocktail of Escherichia coli O157:H7 or Salmonella enterica (5 log CFU/g) and then immersed in a treatment solution containing 5 ppm free chlorine, cinnamaldehyde, or Sporan(®) (800 and 1000 ppm) alone or in combination with 200 ppm acetic acid (20%) for 1 min. Treated leaves were spin-dried and stored at 4°C. Samples were taken to determine the surviving populations of E. coli O157:H7, Salmonella, total coliforms, mesophilic and psychrotrophic bacteria, and yeasts and molds during the 14-day storage period. The effect of treatments on lettuce color and texture was also determined. Cinnamaldehyde-Tween (800 ppm, 800T) reduced E. coli O157:H7 by 2.89 log CFU/g (p<0.05) on iceberg lettuce at day 0; Sporan(®)-acetic acid (1000SV) reduced E. coli O157:H7 and Salmonella on iceberg and romaine lettuce by 2.68 and 1.56 log CFU/g (p<0.05), respectively, at day 0. The effect of essential oils was comparable to that of 5 ppm free chlorine in reducing E. coli O157:H7 and Salmonella populations on iceberg and romaine lettuce throughout the storage time. The natural microbiota on treated lettuce leaves increased during the storage time, but remained similar (p>0.05) to those treated with chlorine and control (water). The texture and the color of iceberg and romaine lettuce treated with essential oils were not different from the control lettuce after 14 days of storage. This study demonstrates the potential of Sporan(®) and cinnamaldehyde as effective lettuce washes that do not affect lettuce color and texture.


Assuntos
Anti-Infecciosos/farmacologia , Escherichia coli O157/efeitos dos fármacos , Lactuca/microbiologia , Óleos Voláteis/farmacologia , Salmonella enterica/efeitos dos fármacos , Ácido Acético/farmacologia , Acroleína/análogos & derivados , Acroleína/farmacologia , Cloro/farmacologia , Contagem de Colônia Microbiana , Desinfetantes/farmacologia , Escherichia coli O157/crescimento & desenvolvimento , Escherichia coli O157/fisiologia , Manipulação de Alimentos , Microbiologia de Alimentos , Folhas de Planta/microbiologia , Óleos de Plantas/farmacologia , Salmonella enterica/crescimento & desenvolvimento , Salmonella enterica/fisiologia , Fatores de Tempo
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