Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 15.326
Filtrar
1.
J Environ Radioact ; 222: 106307, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892894

RESUMO

In Japan, the radiocesium activity concentration in milk must be less than 50 Bq/kg-fresh to meet shipping standards, and the radiocesium concentration of the diet fed to dairy cattle must be less than 500 Bq/kg-dry. After the Fukushima nuclear accident in 2011, we conducted two experiments to investigate whether Prussian blue (PB) could suppress the radiocesium (134Cs + 137Cs) activity concentration in Japanese cattle' milk. In experiment 1, four cattle were fed a diet with a radiocesium activity concentration of 175 Bq/kg-dry, with or without PB supplementation. The PB intake ranged from 0 to 3.0 g/day, and the average radiocesium intake was 3.42 kBq/day in all treatments. The radiocesium activity concentration in milk decreased from 16.4 to 8.6 Bq/kg-fresh, and the transfer coefficient of radiocesium from diet to milk (Fm) decreased from 4.77 × 10-3 to 2.61 × 10-3 with increased PB intake. In experiment 2, three cattle were fed another diet including a radiocesium activity concentration of 927 Bq/kg-dry of with or without PB supplementation. The PB intake ranged from 0 to 18.9 g/day, and the average radiocesium intake was 15.2 kBq/day in all treatments. The milk's radiocesium activity concentration decreased from 24.3 to 4.2 Bq/kg-fresh, and the Fm decreased from 1.68 × 10-3 to 0.28 × 10-3 with increased PB intake. Our results suggest that both the radiocesium activity concentration in milk and Fm can be reduced by PB, and that Fm is affected by diet. We recommend cattle should be fed absorbents such as PB to minimize the risk of milk radiocesium activity concentration exceeding 50 Bq/kg-fresh even if the diet has a radiocesium activity concentration of less than 500 Bq/kg-dry.


Assuntos
Radioisótopos de Césio , Acidente Nuclear de Fukushima , Leite , Monitoramento de Radiação , Animais , Bovinos , Radioisótopos de Césio/análise , Dieta , Ferrocianetos , Japão , Leite/química
2.
PLoS One ; 15(8): e0237262, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760129

RESUMO

The factors that influence the diversity and composition of raw milk and fecal microbiota in healthy commercial dairy herds are not fully understood, partially because the majority of metataxonomic studies involve experimental farms and/or single factors. We analyzed the raw milk and fecal microbiota of 100 healthy cows from 10 commercial alpine farms from the Province of Trento, Italy, using metataxonomics and applied statistical modelling to investigate which extrinsic and intrinsic parameters (e.g. herd, diet and milk characteristics) correlated with microbiota richness and composition in these relatively small traditional farms. We confirmed that Firmicutes, Ruminococcaceae and Lachnospiraceae families dominated the fecal and milk samples of these dairy cows, but in addition, we found an association between the number of observed OTUs and Shannon entropy on each farm that indicates higher microbiota richness is associated with increased microbiota stability. Modelling showed that herd was the most significant factor affecting the variation in both milk and fecal microbiota composition. Furthermore, the most important predictors explaining the variation of microbiota richness were milk characteristics (i.e. percentage fat) and diet for milk and fecal samples, respectively. We discuss how high intra-herd variation could affect the development of treatments based on microbiota manipulation.


Assuntos
Bactérias/isolamento & purificação , Bovinos/microbiologia , Indústria de Laticínios , Fezes/microbiologia , Leite/microbiologia , Ração Animal/análise , Animais , Bactérias/classificação , Dieta , Gorduras/análise , Feminino , Microbiota , Leite/química
3.
J Chromatogr A ; 1627: 461387, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823095

RESUMO

A simple and efficient magnetic solid-phase extraction (MSPE) method was established with magnetic covalent organic framework (COF) as adsorbent to enrich organophosphorus pesticides from fatty milk samples, followed by the sensitive determination via LC-MS/MS. The key parameters influencing the MSPE efficiency were comprehensively investigated to afford an optimized procedure. All the target analytes could be captured directly by magnetic COF from milk without protein precipitation, making the pretreatment rapid and convenient. Systematic method validation demonstrated its satisfactory linearity, recoveries (80.0-105 %), and precision (RSDs <12.3 %). The method limits of quantification were 0.2-0.5 µg L-1. A comparison experiment to the reported solid-phase extraction fully verified the present MSPE more rapid, accurate, and environment-friendly. Furthermore, FT-IR and XPS analysis were performed to reveal the adsorption mechanisms of magnetic COF to organophosphorus pesticides, which could offer guidance on the rational design of COF adsorbent for various target analytes.


Assuntos
Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Leite/química , Compostos Organofosforados/análise , Praguicidas/análise , Extração em Fase Sólida/métodos , Acetonitrilos/análise , Adsorção , Animais , Limite de Detecção , Espectroscopia Fotoeletrônica , Padrões de Referência , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier
4.
PLoS One ; 15(8): e0235357, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760112

RESUMO

We evaluated the between-cow (b-cow) variation and repeatability in omasal and milk fatty acids (FA) related to methane (CH4) emission. The dataset was originated from 9 studies with rumen-cannulated dairy cows conducted using either a switch-back or a Latin square design. Production of CH4 per mole of VFA (Y_CH4VFA) was calculated based on VFA stoichiometry. Experiment, diet within experiment, period within experiment, and cow within experiment were considered as random factors. Empirical models were developed between the variables of interest by univariate and bivariate mixed model regression analysis. The variation associated with diet was higher than the b-cow variation with low repeatability (< 0.25) for milk odd- and branch-chain FA (OBCFA). Similarly, for de novo synthesized milk FA, diet variation was ~ 3-fold greater than the b-cow variation; repeatability for these FA was moderate to high (0.34-0.58). Also, for both cis-9 C18:1 and cis-9 cis-12 cis-15 C18:3 diet variation was more than double the b-cow variation, but repeatability was moderate. Among the de novo milk FA, C4:0 was positively related with stoichiometric Y_CH4VFA, while for OBCFA, anteiso C15:0 and C15:0 were negatively related with it. Notably, when analyzing the relationship between omasal FA and milk FA we observed positive intercept estimates for all the OBCFA, which may indicate endogenous post-ruminal synthesis of these FA, most likely in the mammary gland. For milk iso C13:0, iso C15:0, anteiso C15:0, and C15:0 were positively influenced by omasal proportion of their respective FA and by energy balance. In contrast, the concentration of milk C17:0, iso C18:0, C18:0, cis-11 C18:1, and cis-9 cis-12 cis-15 C18:3 were positively influenced by omasal proportion of their respective FA but negatively related to calculated energy balance. Our findings demonstrate that for most milk FA examined, a larger variation is attributed to diet than b-cow differences with low to moderate repeatability. While some milk FA were positively or negatively related with Y_CH4VFA, there was a pronounced effect of calculated energy balance on these estimates. Additionally, even though OBCFA have been indicated as markers of rumen function, our results suggest that endogenous synthesis of these FA may occur, which therefore, may limit the utilization of milk FA as a proxy for CH4 predictions for cows fed the same diet.


Assuntos
Variação Biológica da População , Efeito Estufa , Lactação/fisiologia , Metano/metabolismo , Leite/química , Ração Animal , Animais , Bovinos , Indústria de Laticínios , Conjuntos de Dados como Assunto , Ácidos Graxos/análise , Feminino , Rúmen/metabolismo
5.
J Chromatogr A ; 1626: 461364, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797843

RESUMO

A new type of restricted access media-imprinted nanomaterials (RAM-MIPs) were successfully prepared on the surface of metal-organic framework by reversible addition fragmentation chain transfer polymerization technology. Then it was applied as a dispersed solid phase extraction (DSPE) material in analysis of fluoroquinolones (ofloxacin, pefloxacin, norfloxacin, enrofloxacin and gatifloxacin) in untreated milk and river water by HPLC-UV detection. The resulted material has a good binding amounts (60.81 mg g-1), rapid binding kinetic (15 min) and satisfactory selectivity as well as has a good ability to eliminate matrix interference. Several major factors affecting DSPE efficiency, pH of sample solution, dosage of RAM-MIPs, adsorption time and volume ratios of elution solvent were primarily optimized. In optimization conditions, RAM-MIPs-DSPE was combined with HPLC-UV to enrich fluoroquinolones in untreated milk and river water, achieving satisfactory linear correlation (R2 > 0.9988), good limits of detection (LOD, 1.02-3.15 µg L-1 for milk and 0.93-2.87 µg L-1 for river water) and better recoveries (80.7-103.5% and 85.1-105.9% with relative standard deviation (RSD) of not higher than 5.3% and 4.7% for milk and river water samples, respectively). The research results illustrate that it provides a simple and efficient method for the direct detection of FQs in complex samples.


Assuntos
Antibacterianos/análise , Fluoroquinolonas/análise , Estruturas Metalorgânicas/química , Leite/química , Nanoestruturas/química , Rios/química , Extração em Fase Sólida/métodos , Adsorção , Animais , Antibacterianos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Fluoroquinolonas/isolamento & purificação , Impressão Molecular , Polimerização
6.
J Chromatogr A ; 1627: 461400, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823105

RESUMO

In this work, a single cross-linking functional monomer, 2,5-divinylterephthalaldehyde, was designed and synthesized to simplify the preparation of molecularly imprinted polymers (MIPs). In the presence of estradiol as a template, MIPs were successfully prepared using 2,5-divinylterephthalaldehyde along with a solvent and initiator. This method reduced most of the complex variables encountered in the traditional synthesis. Characterization of the morphology and structure of the MIPs was performed by scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. Compared with non-imprinted polymers, the MIPs had higher adsorption capacities for five estrogens with imprinting factors above 2.9. The MIPs had high extraction efficiencies, good functional properties, long lifetimes, and good reproducibility, which made them suitable for solid-phase microextraction (SPME). Coupled with ultra-high performance liquid chromatography tandem mass spectrometry, the MIP-based fibers were applied to SPME for the analysis of five estrogens in milk samples. Under the best conditions, the established method had a wide linear range (0.5-10000 ng kg-1), low limits of detection (0.08-0.26 ng kg-1) and quantification (0.26-0.87 ng kg-1), good precision (3.2-8.1%, n = 6), and fiber-to-fiber reproducibility (4.3%-8.8%, n = 3). The MIPs-based fibers can be reused at least 60 times without apparent loss of extraction efficiency. Finally, this method was applied to the determination of target estrogens in milk samples with satisfactory relative recoveries (84.3%-105%, relative standard deviation ≤ 7.8%).


Assuntos
Estrogênios/isolamento & purificação , Leite/química , Impressão Molecular , Polímeros/química , Microextração em Fase Sólida/métodos , Adsorção , Animais , Cromatografia Líquida de Alta Pressão , Estradiol/análise , Estrogênios/análise , Limite de Detecção , Reprodutibilidade dos Testes , Solventes/química , Espectrometria de Massas em Tandem
7.
Ecotoxicol Environ Saf ; 204: 111066, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32781344

RESUMO

In this study, an iron-doped metal-organic framework (MOF) Fe/ZIF-8 was synthesized from ZIF-8 at room temperature. Direct carbonization of Fe/ZIF-8 under a nitrogen atmosphere produced nanoporous nitrogen doped carbon nanoparticles decorated with Fe component (Fe/NC). The Fe/NC exhibited a large surface area (1221.185 m2 g-1) and narrow pore-size distribution (3-5 nm). The nanoporous Fe/NC components along with Nafion were used to modify a glassy carbon electrode for the electrochemical determination of chloramphenicol and metronidazole via linear sweep voltammetry. Under optimal conditions, the reduction peak currents (observed at -0.237 V and -0.071 V vs. Ag/AgCl) of these analytes increased linearly with increasing chloramphenicol and metronidazole concentrations in the range of 0.1-100 µM and 0.5-30 µM, with the detection limits estimated to be 31 nM and 165 nM, respectively. This result was attributed to the large surface area, porous structure, high nitrogen content, and as well as the electrocatalytic effect of Fe atoms embeded in the carbon support. The proposed sensor was used for chloramphenicol and metronidazole analysis in samples, providing satisfactory results.


Assuntos
Carbono/química , Cloranfenicol/análise , Técnicas Eletroquímicas/métodos , Ferro/química , Estruturas Metalorgânicas/química , Metronidazol/análise , Nitrogênio/química , Animais , Cloranfenicol/urina , Eletrodos , Humanos , Limite de Detecção , Metronidazol/urina , Leite/química , Nanoporos , Soluções Oftálmicas/química , Porosidade , Comprimidos/química
8.
PLoS One ; 15(8): e0237615, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32780761

RESUMO

The impact of cow mammary gland diseases on the quality of colostrum is not conclusively defined; research results are conflicting. However, it is widely believed that mastitis lowers the level of immunoglobulins and the quality of the colostrum produced. Therefore, the aim of this study was to determine the influence of somatic cell counts (SCC) on the colostrum immunostimulating and chemical components. The experiment was conducted on an experimental organic dairy farm in which a herd of approximately 250 cows was kept in a freestall housing system, with the average performance exceeding 6,000 kg of milk per lactation. Colostrum and milk samples were taken individually from each cow seven times during the experiment: from the first to second day after calving-twice per day, and from the third to fifth day after calving-once per day. Therefore, after preliminary analyses, the cows were divided into two groups based on the cytological quality of their colostrum at the first collection: 1. SCC ≤400,000 cells/ml (good quality colostrum; GCC- 18 cows), 2. SCC ≥ 400,000 cells/ml (low quality colostrum; LCC- 22 cows). The study found almost double the concentration of immunoglobulins and essential fatty acids in first milking colostrum in the GCC group than in colostrum from the LCC group. In addition, an increase in the concentration of lysozyme in first milking colostrum was associated with a decrease in the concentration of immunoglobulins. In addition, the increase in the level of lysozyme was associated with a decrease in the concentration of immunoglobulins. In conclusion, the SCC of first milking colostrum can be used as an indicator of colostrum quality.


Assuntos
Contagem de Células/veterinária , Colostro/metabolismo , Indústria de Laticínios/métodos , Lactação/metabolismo , Leite/química , Leite/citologia , Animais , Bovinos , Feminino , Gravidez
9.
PLoS One ; 15(8): e0237608, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817620

RESUMO

The application of biomolecular techniques to archaeological materials from the Balkans is providing valuable new information on the prehistory of the region. This is especially relevant for the study of the neolithisation process in SE Europe, which gradually affected the rest of the continent. Here, to answer questions regarding diet and subsistence practices in early farming societies in the central Balkans, we combine organic residue analyses of archaeological pottery, taxonomic and isotopic study of domestic animal remains and biomolecular analyses of human dental calculus. The results from the analyses of the lipid residues from pottery suggest that milk was processed in ceramic vessels. Dairy products were shown to be part of the subsistence strategies of the earliest Neolithic communities in the region but were of varying importance in different areas of the Balkan. Conversely, milk proteins were not detected within the dental calculus. The molecular and isotopic identification of meat, dairy, plants and beeswax in the pottery lipids also provided insights into the diversity of diet in these early Neolithic communities, mainly based on terrestrial resources. We also present the first compound-specific radiocarbon dates for the region, obtained directly from absorbed organic residues extracted from pottery, identified as dairy lipids.


Assuntos
Agricultura/métodos , Cerâmica/química , Indústria de Laticínios/métodos , Dieta , Lipídeos/análise , Proteínas do Leite/análise , Leite/química , Animais , Arqueologia , Península Balcânica , Fazendeiros , Humanos , Ceras
10.
Endocrinol. diabetes nutr. (Ed. impr.) ; 67(6): 383-393, jun.-jul. 2020. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-193363

RESUMO

ANTECEDENTES Y OBJETIVOS: La leche ultrapasteurizada (leche UHT) de vaca es la más consumida en el suroeste europeo. Los objetivos del estudio fueron: 1) describir el patrón que sigue la concentración de yodo (CY) en la leche convencional UHT de vaca a lo largo del año y 2) averiguar si existen diferencias en la CY en este tipo de leche según su procedencia geográfica. MATERIAL Y MÉTODOS: Se compraron briks de leche convencional UHT de vaca de marcas comerciales disponibles en los grandes establecimientos de alimentación de Vitoria-Gasteiz (Araba/Álava) durante 12 meses consecutivos y se determinó su CY mediante cromatografía líquida de alta resolución. RESULTADOS: La mediana (P25-P75) de la CY en la leche (n = 489) fue de 190 (159-235) μg/L. La CY experimentó grandes variaciones a lo largo del año, alcanzando valores máximos entre enero y mayo, 241 (201-272) μg/L, y mínimos entre julio y noviembre, 162 (134-185) μg/L (p < 0,0001). La CY de la leche envasada en Alemania fue significativamente menor que la de las leches envasadas en España y en Francia, 119 (106-156) μg/L frente a 189 (159-229) μg/L y 205 (176-243) μg/L respectivamente (p < 0,0001). CONCLUSIONES: La leche convencional UHT de vaca es una fuente alimentaria muy importante de yodo, pero su CY es altamente variable. Conocer el patrón que sigue la CY en la leche a lo largo del año tiene mucho interés para la planificación de los estudios epidemiológicos sobre el estado de nutrición de yodo en escolares y para la interpretación de los resultados


BACKGROUND AND OBJECTIVES: Ultra-high temperature (UHT) processed cow milk is the milk most commonly consumed in Southwest Europe. The study objectives were: 1) to describe the pattern followed by iodine concentration (IC) in conventional UHT milk over the year, and 2) to find out any differences in IC in this type of milk depending on its geographical origin. MATERIAL AND METHODS: Bricks of conventional UHT cow milk of commercial brands available in food stores in Vitoria-Gasteiz (Araba/Álava), Basque Country (Spain) were bought for 12 consecutive months, and their ICs were measured using high performance liquid chromatography. RESULTS: Median (P25-P75) IC in UHT milk (n = 489) was 190 (159-235) μg/L. IC in milk showed great changes over the year, reaching peak values between January and May (241 [201-272] μg/L), and minimal levels between July and November (162 [134-185] μg/L) (P < .0001). The IC of milk packed in Germany was significantly lower than that of milks packed in Spain and France, 119 (106-156) μg/L versus 189 (159-229) μ g/L and 205 (176-243) μg/L respectively (P < .0001). CONCLUSIONS: Conventional UHT cow milk is a very important nutritional source of iodine, but its IC is highly variable. Knowledge of the pattern followed by IC in milk over the year is of great interest for planning epidemiological studies on iodine nutritional status in schoolchildren and for interpretation of their results


Assuntos
Humanos , Leite/química , Estado Nutricional , Iodo/análise , Substitutos do Leite Humano , Pasteurização/métodos , Iodo/administração & dosagem , Estudos Longitudinais , Compostos de Iodo/química , Nutrição do Lactente , Intervalos de Confiança
11.
J Chromatogr A ; 1625: 461275, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709327

RESUMO

Efficient extraction of polar sulfonamides antibiotics from aqueous samples and food is very challenging, because they are hydrophilic, their concentration is very low, and the matrix is complex. Covalent organic frameworks (COFs), a novel porous organic material, have attracted great attention. In this work, the spherical triphenylbenzene-dimethoxyterephthaldehyde-COFs (TPB-DMTP-COFs) were synthesized by a simple room temperature method, and due to their attractive properties, such as high outstanding acid-base stability, large specific surface area, low skeletal density, inherent porosity and high crystallinity, so TPB-DMTP-COFs as ideal solid phase extraction adsorbents showed excellent adsorption performance for trace polar sulfonamides in food and water. TPB-DMTP-COFs were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, and so on. The important parameters were optimized to improve the extraction efficiency of TPB-DMTP-COFs toward sulfonamides. Analysis of sulfonamides was performed by liquid chromatography-tandem mass spectrometry. The developed method based on TPB-DMTP-COFs material achieved low limits of detection (0.5-1.0 ng L-1), wide linearity (5-1000 ng L-1), and good repeatability (2.5%-8.7%). The possible extraction mechanism was also discussed. Finally, the method was successfully applied to the enrichment and detection of sulfonamides in environmental water samples and food samples. The present study indicated that TPB-DMTP-COFs had splendid prospects in highly sensitive analysis of other pollutants in complex matrix.


Assuntos
Análise de Alimentos , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Sulfonamidas/análise , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Adsorção , Animais , Cromatografia Líquida , Contaminação de Alimentos/análise , Leite/química , Carne de Porco/análise , Porosidade , Sulfonamidas/química , Água/química
12.
Food Chem ; 332: 127371, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32622188

RESUMO

A simple and sensitive salting out-assisted dispersive liquid-liquid microextraction method using deep eutectic solvent combined with back extraction and micellar electrokinetic capillary chromatography (SO-DLLME-DES-BE-MECC) was developed for the determination of fluoroquinolones in milk, honey and water samples. Several parameters affecting the extraction efficiency including DES volume, vortex time, centrifugation time, salt type and amount, sample pH and volume, etc. were investigated. Good linearity were obtained for fluoroquinolones in a range of 0.020-3.200 µg mL-1 and 0.030-4.800 µg mL-1 with LODs less than 0.010 µg mL-1. The recoveries were in the ranges of 95.0-104.9%, 90.1-110.2% and 87.8-114.1% for water, honey and milk samples, respectively. The relative standard deviations for reproducibility were all below 7.6%. Under the optimized conditions, the enrichment factors for analytes were achieved in the range from 531 to 858 folds. The presented method was successfully applied for the determination of fluoroquinolones in milk, honey and water samples.


Assuntos
Cromatografia Capilar Eletrocinética Micelar , Fluoroquinolonas/análise , Mel/análise , Microextração em Fase Líquida/métodos , Leite/química , Solventes/química , Água/química , Animais , Fluoroquinolonas/química , Fluoroquinolonas/isolamento & purificação , Limite de Detecção , Sais/química
13.
J Environ Sci Health B ; 55(9): 827-834, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32602778

RESUMO

The present study was carried out with the objectives to determine the occurrence of aflatoxin M1 (AFM1) in raw milk and identification of associated risk factors from three different types of animal farming systems. A total of 189 pooled raw milk samples were tested for AFM1 with enzyme linked immunosorbant assay (ELISA) as screening and high performance liquid chromatography with fluorescence detection (HPLC-FLD) as confirmatory techniques. AFM1 was found positive in 58% pooled milk samples with the mean level of 0.917 µg/L, while 50.8% and 36.5% samples were found above the legal limits set by European Commission (EC) and Food safety and standard authority of India (FSSAI), respectively for AFM1 in milk. Among all investigated risk factors, feeding of readymade concentrate feed and leftover household cereals, longer feed storage duration and feed storage quality were found significantly associated with presence of AFM1 in farm milk. High prevalence as well as levels of AFM1 in farm milk poses a health risk to the consumers especially children. Therefore, efforts are urgently required to create awareness among dairy farmers about aflatoxins contamination of feed and milk, to improve farm management practices and to control AFM1 level in milk below the legal limits.


Assuntos
Aflatoxina M1/análise , Contaminação de Alimentos/análise , Leite/química , Animais , Criança , Cromatografia Líquida de Alta Pressão , Indústria de Laticínios , Ensaio de Imunoadsorção Enzimática , Fazendas , Análise de Alimentos , Humanos , Índia , Medição de Risco , Fatores de Risco
14.
Food Chem ; 333: 127477, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32673956

RESUMO

As a veterinary antibiotic, lincomycin (LIN) residues in milk are raising concerns of public on account of potential harm to human health. Efficient strategy is eagerly desired for detection of LIN from milk samples. Hence, lincomycin molecularly imprinted membranes (LINMIMs) were developed for selective separation of LIN as an efficient pretreatment of milk samples. The synergistic effect of polyethylenimine and dopamine provided effective antifouling performance by improving the hydrophilicity. Based on click chemistry, specific recognition sites were facilely formed on membranes using 4-vinylpyridine as functional monomers. The satisfactory rebinding capacity (151.62 mg g-1), permselectivity (4.43), together with the linear dependence (R2 = 0.9902) of concentrations in eluents and original samples. Moreover, the method was utilized to determine LIN from milk, with good recovery and relative standard deviation. Achievements in this work will actively promote the development of efficient detection technology.


Assuntos
Incrustação Biológica/prevenção & controle , Contaminação de Alimentos/análise , Lincomicina/análise , Lincomicina/isolamento & purificação , Membranas Artificiais , Leite/química , Impressão Molecular , Animais , Resíduos de Drogas/análise , Resíduos de Drogas/isolamento & purificação
15.
Food Chem ; 333: 127488, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32682229

RESUMO

A mild mixed-solvent of n-hexane/isopropanol is proposed for extracting total mineral oil hydrocarbons (MOH) from commercial milk powder products. Unlike acid-hydrolysis, the mixed-solvent extraction was performed at ambient temperature and the low-boiling-point hydrocarbons were retained to the greatest extent. After extraction, total MOH was determined by on-line liquid chromatography-gas chromatography with a flame ionization detector (LC-GC-FID). The validation of the proposed extraction method revealed a recovery efficacy of 83.0-107.5% and a limit of quantification of 0.5 mg/kg. Then, the total MOH in ten commercial milk powders was determined and mineral oil saturated hydrocarbons (MOSH)/polyolefin oligomeric saturated hydrocarbons (POSH) were found to be within the range of 0.61-5.46 mg/kg. The comparison of the total and surface MOSH/POSH indicated that a major part of the contamination was derived from sources before packaging. The present study provides a robust method for the extraction and determination of total MOH in milk powders.


Assuntos
Fracionamento Químico/métodos , Contaminação de Alimentos/análise , Hidrocarbonetos/análise , Hidrocarbonetos/isolamento & purificação , Leite/química , Óleo Mineral/química , Solventes/química , Animais , Hidrocarbonetos/química , Pós
16.
Arch Microbiol ; 202(9): 2525-2532, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32653933

RESUMO

The adverse effects of chemical pesticides on human health and environment cannot be ignored, hence it seems that novel alternative compounds should be applied to control plant pathogens. Among various alternative sources, natural compounds such as plant essential oils, plant extracts and recombinant antimicrobial peptides are of significance. The aim of the present study was to investigate antimicrobial activity of plants essential oils and plant extracts of six medicinal plants (Lippia citriodora, Ferula gummosa, Bunium persicum, Mentha piperita, Plantago major and Salvadora persica) along with a chimera peptide of camel lactoferrin, which is the most important antimicrobial component of camel milk, against Pseudomonas tolaasii and Trichoderma harzianum as pathogens of white button mushroom. The antibacterial activity test was conducted under in vitro conditions through disc diffusion method. The results showed that chimera camel lactoferrin peptide, with the highest amount of inhibitory zone (14.63 mm in 20 µg/mL concentration), has a significant difference in antibacterial activity compared to other treatments. Ferula gummosa conferred no antibacterial activity. Also, the results of antifungal effects indicated that plant essential oils and extracts have more antifungal activity than recombinant peptide. Generally, L. citriodora, B. persicum, M. piperita treatments could completely prevent growth of fungal in in vitro conditions. Therefore, using the mentioned plants can be a good replacement for reducing the chemical pesticides against pathogenic agents of button mushroom, without any adverse effects on environment and human health.


Assuntos
Lactoferrina/farmacologia , Óleos Voláteis/farmacologia , Extratos Vegetais/farmacologia , Pseudomonas/efeitos dos fármacos , Trichoderma/efeitos dos fármacos , Agaricus , Animais , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Antifúngicos/farmacologia , Fungos/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Leite/química , Óleos Vegetais/farmacologia , Plantas Medicinais/química
17.
Food Chem ; 333: 127518, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32712545

RESUMO

A multifunctional visual observation of magnetic ionic liquid (MIL) benzyltrioctylammonium thiocyanatecobalt (II) [N8,8,8,B+]2[Co(SCN)42-] with the long-chain alkyl and benzyl group structures was designed and synthesized as microextraction phase. Designed new structural MIL displays good hydrophobicity, high extraction capacity for both aromatic and aliphatic compounds, and has obvious color markers (blue color) which is easy visual separation from aqueous solution through a magnet. In the present work, a green, efficient and rapid samples pretreatment method based on simultaneous derivatization and extraction of aromatic (tyramine, histamine, phenylethylamine, tryptamine) and aliphatic (spermidine and spermine) biogenic amines (BAs) were performed. Microwave-assisted derivatization coupled with MIL-dispersive liquid-liquid microextraction (DLLME) was established for the determination of six BAs in different food samples via HPLC. The method was successfully applied for the analysis of beer and milk samples, and the recoveries of analytes were 93.0-110.3% and 91.2-111.6%, respectively. The limits of detection (LODs) were 0.51-1.49 µg L-1 for six BAs. These results have demonstrated that the proposed method has offered an effective, accurate, and sensitive methodology for BAs residue detection in food sample, and this method has great potential for the routine analysis of large numbers of samples on measuring different kinds of compounds.


Assuntos
Aminas Biogênicas/isolamento & purificação , Líquidos Iônicos/química , Microextração em Fase Líquida/métodos , Magnetismo , Micro-Ondas , Animais , Cerveja/análise , Aminas Biogênicas/análise , Cromatografia Líquida de Alta Pressão , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Leite/química
18.
Food Chem ; 333: 127529, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32679419

RESUMO

A solid-phase extraction (SPE) method for enriching and purifying estrogenic disrupting compounds (EDCs) based on the estrogen response element was established. The estrogen receptor was used for molecular recognition, as it specifically binds EDCs. An estrogen response element was used to maintain the activity of the estrogen receptor. High-performance liquid chromatography (HPLC) was used to quantify the EDCs. This method combined with HPLC was applied to detect three kinds of EDCs, such as bisphenol A (BPA), 17ß-estradiol, and diethylstilbestrol in a liquid milk matrix, with recoveries of 84.1 ± 8.2% to 113.6 ± 2.9%. The limits of detection and quantification of the established method were 1 × 10-6 mg·mL-1 and 5 × 10-6 mg·mL-1. The method was further applied to analyze market samples, including liquid milk, fermented milk, and milk powder. Only BPA was detected from one brand of liquid milk and it was below the regulatory level.


Assuntos
Disruptores Endócrinos/isolamento & purificação , Estrogênios/metabolismo , Elementos de Resposta , Extração em Fase Sólida/métodos , Animais , Cromatografia Líquida de Alta Pressão , Disruptores Endócrinos/análise , Leite/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
19.
Food Chem ; 333: 127538, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32712546

RESUMO

The effects of water content; 15, 30, and 40% (w/w), water droplet size; d43 15.0-19.6 µm (larger) and d43 1.2-2.7 µm (smaller), and sodium alginate (0.5%, w/w) induced water gelation on crystallization kinetics and water and fat proton relaxation were studied in water-in-milk fat emulsions during in situ cooling from 40 °C to 5 °C. Anhydrous milk fat (AMF) and commercial butter were employed as two separate fat sources. Although emulsions were crystallized faster than the bulk fat, the variations in the water fraction and droplet size did not show major influence on crystallization properties. Smaller droplet size induced significant (p < 0.05) reduction in water mobility with a minimal effect of the temperature. In AMF-based emulsions, gelation of water phase not only immobilized the water molecules but also enhanced the rate of fat crystallization. Globular fat and serum solids in butter-based emulsions showed to fasten the water proton relaxation.


Assuntos
Ácidos Graxos/química , Leite/química , Movimento (Física) , Transição de Fase , Água/química , Animais , Manteiga/análise , Cristalização , Emulsões , Géis , Cinética , Temperatura
20.
Food Chem ; 333: 127421, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32653681

RESUMO

An extraction procedure was developed for the determination of aflatoxin M1 in milk and dairy products. A sorbent based on UVM-7 mesoporous silica was used as solid phase for the sample clean-up, and the analyte determination was carried out by HPLC coupled to a fluorescence detector. The material architecture was characterized by transmission electronic microscopy, X-ray diffraction, 29Si NMR and nitrogen adsorption-desorption. After the optimization of extraction parameters, the influence of the matrix has been evaluated, obtaining recoveries in the range 78-105% for whole and skimmed milk and yogurt matrix. The reusability of the material was also proved. The sensitivity of the method was also evaluated, and a LOQ (0.015 µg kg-1) below the European legislation limit was obtained. The procedure was successfully applied for the determination of aflatoxin M1 in real samples. The results were compared with those obtained with a reference method, being the results statistically comparable.


Assuntos
Aflatoxina M1/análise , Custos e Análise de Custo , Análise de Alimentos/métodos , Leite/química , Nanoestruturas/química , Dióxido de Silício/química , Iogurte/análise , Adsorção , Aflatoxina M1/química , Animais , Fluorescência , Análise de Alimentos/economia , Contaminação de Alimentos/análise , Limite de Detecção , Porosidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA