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3.
Food Technol Biotechnol ; 56(3): 337-343, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30510477

RESUMO

The oxidation mechanism of all-trans-retinol (vitamin A1) and its several esters in non-aqueous, aqueous organic mixture, and pure aqueous media was investigated by cyclic voltammetry. The oxidation occurred in several irreversible steps. The calculated highest density of electrons in retinoid molecules which are delocalized over carbon atoms of the five conjugated double bonds (C5-C14) was found in the part of the molecule involved in oxidation processes. The most sensitive oxidation peak (at +0.8 V vs. Ag/AgCl) was used for development of new direct voltammetric method based on differential pulse voltammetry for the determination of retinol at carbon paste electrode modified with surfactant sodium dodecyl sulfate (CPE/SDS). The results show that 30% (by mass) of modifier SDS exhibited optimal sensitivity and shape of voltammograms. Compared to commonly used glassy carbon electrode (GCE), the CPE/SDS showed significant progress in the retinol electroanalysis. The linear ranges for retinol determination were 1.5·10-6-1.8·10-4 M for CPE/SDS and 4.4·10-6-7.0·10-4 M for GCE with the detection limits of 1.3·10-6 and 4.6·10-7 M, respectively.

4.
Plant Foods Hum Nutr ; 71(4): 429-435, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27679438

RESUMO

Buckwheat cookies with various ingredients for raw food vegan diet are usually prepared by soaking them in water at ambient temperature followed by drying at moderate temperature. The aim of this study was to examine the temperature effect on the microbiological quality, antioxidant properties and oxidative stability of lipids of final dried samples. The mixture of ingredients was soaked for 20 h in distilled water, and then cookies were formed and dried in air-forced oven at constant temperature in the range from 40 to 60 °C. Total viable counts, fungi, yeasts, coliform and aerobic spore-forming bacteria counts were evaluated in dried samples and were found to decrease during drying at 50 and 60 °C. Antioxidant activity was determined by DPPH and ABTS assays, and the former showed the highest value at 40 °C. Superoxide dismutase activity was also higher at 40 °C in comparison with that at 60 °C. The percentage of lipid peroxidation inhibition increased with the increase in drying temperature until 4th day of incubation. While peroxide value was significantly higher in samples dried at 40 °C, TBARS values did not show significant changes during the drying process. The results of this study suggest that drying buckwheat-based cookies at 40 °C retained their good antioxidant properties but represent a potentially serious microbial hazard.


Assuntos
Antioxidantes/farmacologia , Dessecação , Dieta Vegana , Fagopyrum/química , Alimentos Crus/análise , Antioxidantes/análise , Carga Bacteriana , Fagopyrum/microbiologia , Contaminação de Alimentos/análise , Manipulação de Alimentos , Microbiologia de Alimentos , Peroxidação de Lipídeos , Superóxido Dismutase/metabolismo , Temperatura Ambiente , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Água/análise
5.
Food Technol Biotechnol ; 53(4): 379-384, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27904372

RESUMO

In this paper, a pencil graphite electrode was pretreated using chronoamperometry technique in phosphate buffer solution (pH=7.0) for sensitive determination of quercetin. Oxidation of quercetin was investigated using pretreated pencil graphite electrode and anodic stripping differential pulse voltammetry. Under optimal conditions, the anodic current of quercetin exhibited linear response to its concentration in the range from 0.001 to 1.5 µmol/L with the limit of detection of 0.3·10-3 µmol/L. The proposed method was successfully applied for the determination of quercetin in cranberry and blackcurrant juices with recovery rate from 93.2 to 94.7%. Solid-phase extraction was found to be necessary prior to voltammetric determination of quercetin in fruit juice samples using pretreated pencil graphite electrode.

6.
Anal Sci ; 28(11): 1075-80, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23149608

RESUMO

This study investigates a new approach for the electrocatalytic determination of sulfide in a flow injection analysis (FIA) system using a Prussian blue modified glassy carbon electrode (PB/GCE). The results from experiments show that PB/GCE significantly enhances the electrocatalytic activity towards sulfide oxidation. A homemade flow electrochemical cell was used to perform the electrocatalytic determination of sulfide in the FIA system. The currents obtained from amperometric measurements in the FIA system at optimum conditions (carrier solution, pH 8.0; Britton-Robinson buffer solution containing 0.1 M KCl; flow rate, 1.4 mL/min; transmission tubing length, 10 cm; injection volume, 100 µL; constant applied potential, +150 mV vs. Ag/AgCl/KClsat) were linearly correlated with the sulfide concentration. A calibration curve was obtained for sulfide concentrations in the range of 0.5 - 100 µM. The detection limit was found to be 0.3 µM for the amperometric method. The proposed method was successfully applied to wastewater sample. Finally, results from sulfide measurements by PB/GCE were in good agreement with those obtained from the spectrophotometric method.


Assuntos
Carbono/química , Ferrocianetos/química , Análise de Injeção de Fluxo , Sulfetos/análise , Catálise , Técnicas Eletroquímicas , Eletrodos , Vidro/química , Propriedades de Superfície , Poluentes Químicos da Água/química
7.
Braz. j. microbiol ; 39(3): 517-520, July-Sept. 2008. tab
Artigo em Inglês | LILACS | ID: lil-494543

RESUMO

The persistence of A. butzleri CCUG 30484 on various surfaces under 32 percent and 64 percent relative humidity suspended in physiological saline or nutrient broth to simulate relatively clean or soiled conditions was studied using various isolation techniques. Our study revealed that A. butzleri CCUG 30484 cells were able to survive for a considerable period of time, even after the droplet of suspending medium has been visibly dried. An extended survival on polypropylene coupons at both humidity levels was observed, particularly at soiled conditions.


Estudou-se a persistência de Arcobacter butzleri CCUG 30404 em várias superfícies de contato com alimentos a 32 por cento e 64 por cento de umidade relativa, suspenso em salina fisiológica e caldo nutriente para simular condições limpas e sujas. Nosso estudo indicou que A. butzleri CCUG 30404 foi capaz de sobreviver por longo tempo, mesmo após a secagem da gota. Observou-se que a sobrevivência for mais prolongada nos cupons de polipropileno, especialmente em condições sujas.


Assuntos
Arcobacter/isolamento & purificação , Meios de Cultura , Umidade , Plásticos/isolamento & purificação , Métodos , Técnicas
8.
J Ind Microbiol Biotechnol ; 35(11): 1247-52, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18712552

RESUMO

Antimicrobial properties of oxidized cellulose and its salts in linters (-L) and microsphere (-M) form (OKCEL H-L, OKCEL Zn-M, OKCEL ZnNa-L, OKCEL ZnNa-M and OKCEL Ag-L) were tested by a dilution method against a spectrum of microbial strains: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, Bacillus licheniformis, Aspergillus niger, Penicillium chrysogenum, Rhizopus oryzae, Scopulariopsis brevicaulis, Candida albicans and Candida tropicalis. OKCEL Ag-L exhibited antimicrobial activity in the range 0.1-3.5% w/v against all the bacteria and fungi involved in this study. Strong inhibition by OKCEL ZnNa-M was observed for Staphylococcus epidermidis, Bacillus licheniformis, Rhizopus oryzae, Candida albicans and Candida tropicalis in the range 0.5-2.0% w/v. Antimicrobial effects of oxidized cellulose and its salts in textile form were investigated by a diffusion and dilution method against the spectrum of above-cited microbial strains extended by Clostridium perfringens. Generally, OKCEL Ag-T, OKCEL Zn-T and OKCEL H-T showed high antimicrobial activity against populations of Pseudomonas aeruginosa, Bacillus licheniformis and Staphylococcus epidermidis. OKCEL Zn-T was the only sample suppressing the growth of species.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Bactérias/efeitos dos fármacos , Celulose Oxidada/farmacologia , Fungos/efeitos dos fármacos , Antibacterianos/química , Antifúngicos/química , Celulose Oxidada/química , Química Farmacêutica , Sais/química , Sais/farmacologia
9.
J Food Prot ; 71(1): 165-9, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18236678

RESUMO

The inhibitory effect of some plant oil aromatics against three strains of Arcobacter butzleri, two strains of Arcobacter cryaerophilus, and one strain of Arcobacter skirrowii was evaluated. When MICs were determined using the broth macrodilution method, cinnamaldehyde was most inhibitory followed by thymol, carvacrol, caffeic acid, tannic acid, and eugenol (P < 0.001). Sublethal concentrations of the three most potent plant oil aromatics also were examined. Overall, cinnamaldehyde was the most bacteriostatic against all arcobacters tested except A. butzleri when these strains were exposed to the MIC25 of this aromatic aldehyde. The bacteriostatic activities of thymol and carvacrol were concentration and species dependent.


Assuntos
Arcobacter/efeitos dos fármacos , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Óleos Vegetais/farmacologia , Acroleína/análogos & derivados , Acroleína/farmacologia , Arcobacter/crescimento & desenvolvimento , Ácidos Cafeicos/farmacologia , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Relação Dose-Resposta a Droga , Eugenol/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Monoterpenos/farmacologia , Óleos Vegetais/química , Especificidade da Espécie , Taninos/farmacologia , Timol/farmacologia
10.
Braz J Microbiol ; 39(3): 517-20, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24031258

RESUMO

The persistence of A. butzleri CCUG 30484 on various surfaces under 32% and 64% relative humidity suspended in physiological saline or nutrient broth to simulate relatively clean or soiled conditions was studied using various isolation techniques. Our study revealed that A. butzleri CCUG 30484 cells were able to survive for a considerable period of time, even after the droplet of suspending medium has been visibly dried. An extended survival on polypropylene coupons at both humidity levels was observed, particularly at soiled conditions.

11.
Crit Rev Microbiol ; 33(2): 101-8, 2007 Apr-Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17558659

RESUMO

Arcobacter spp. has been isolated from food of animal origin (particularly meats) and from various kind of water. Despite its phylogenetically related neighbor Campylobacter, Arcobacter is regarded as an emerging foodborne pathogen. Since Arcobacter differs in its phenotypic characteristics, the physical and chemical treatments designed for elimination of campylobacters from food and environment needs to be verified. This review focuses on the occurrence, and mainly on susceptibility to various physical and chemical treatments for inactivation of Arcobacter spp. The existing studies have been critically discussed and new challenges were proposed for further studies.


Assuntos
Arcobacter/fisiologia , Microbiologia de Alimentos , Viabilidade Microbiana , Microbiologia da Água , Antibacterianos/farmacologia , Arcobacter/efeitos dos fármacos , Arcobacter/efeitos da radiação , Temperatura Alta , Concentração de Íons de Hidrogênio , Temperatura Ambiente
12.
Curr Microbiol ; 53(5): 435-9, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16972127

RESUMO

Seventeen spice and medicinal plant extracts (methanol and chloroform) were assayed for their antimicrobial activity against Arcobacter butzleri, A. cryaerophilus, and A. skirrowii. In general, all of the tested extracts were able, to a different extent, to inhibit the growth of the selected Arcobacter species. Cinnamon, bearberry, chamomile, sage and rosemary extracts showed strong antimicrobial activity toward arcobacter strains tested. Overall, the methanol extracts showed better activity than the chloroform extracts (P < 0.05); however, enhanced antibacterial activity of chloroform extracts of cinnamon and rosemary has been observed in comparison with their methanol counterparts. The inhibitory dose of the most active extracts (the diameter of zone of inhibition > or = 20 mm) was determined using the disc-diffusion method as well.


Assuntos
Arcobacter/efeitos dos fármacos , Extratos Vegetais/farmacologia , Especiarias , Testes de Sensibilidade Microbiana
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