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1.
J AOAC Int ; 88(4): 1205-11, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16152941

RESUMO

A simple and inexpensive liquid chromatography/mass spectrometry (LC/MS) method was developed for the quantitation of acrylamide in various food products. The method involved spiking the isotope-substituted internal standard (1-C13 acrylamide) onto 6.00 g of the food product, adding 40 mL distilled/deionized water, and heating at 65 degrees C for 30 min. Afterwards, 10 mL ethylene dichloride was added and the mixture was homogenized for 30 s and centrifuged at 2700 x g for 30 min, and then 8 g supernatant was extracted with 10, 5, and 5 mL portions of ethyl acetate. The extracts were combined, dried with sodium sulfate, and concentrated to 100-200 microL. Acrylamide was determined by analysis of the final extract on a single quadrupole, bench-top mass spectrometer with electrospray ionization, using a 2 mm id C18 column and monitoring m/z = 72 (acrylamide) and m/z = 73 (internal standard). For difficult food matrixes, such as coffee and cocoa, a solid-phase extraction cleanup step was incorporated to improve both chromatography and column lifetime. The method had a limit of quantitation of 10 ppb, and coefficients of determination (r2) for calibration curves were typically better than 0.998. Acceptable spike recovery results were achieved in 11 different food matrixes. Precision in potato chip analyses was 5-8% (relative standard deviation). This method provides an LC/MS alternative to the current LC/MS/MS methods and derivatization gas chromatography/mass spectrometry methods, and is applicable to difficult food products such as coffee, cocoa, and high-salt foods.


Assuntos
Acrilamida/análise , Técnicas de Química Analítica/métodos , Cromatografia Líquida/métodos , Análise de Alimentos/métodos , Contaminação de Alimentos , Espectrometria de Massas/métodos , Acetatos/análise , Cacau , Técnicas de Química Analítica/instrumentação , Cromatografia , Café , Cromatografia Gasosa-Espectrometria de Massas/métodos , Pós , Padrões de Referência , Reprodutibilidade dos Testes , Solanum tuberosum , Sulfatos/farmacologia , Temperatura
2.
Eur J Mass Spectrom (Chichester) ; 11(2): 217-20, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16046806

RESUMO

2-Acetyltetrahydropyridine is an important flavor component in heated corn products such as popcorn and corn chips. The compound exists as a mixture of two tautomers that have different flavor/aroma characteristics. The tautomers also exhibit different chromatographic behaviors and are distinguishable spectroscopically. Though their electron ionization mass spectra are different, structure assignment based on low-resolution mass spectra alone has been subject to error. A combination of high resolution exact mass measurement and vapor phase infrared measurement of the separated tautomers was used to unambiguously assign the tautomer structures.


Assuntos
Aromatizantes/química , Análise de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Piridinas/química , Aromatizantes/análise , Estrutura Molecular , Odorantes/análise , Piridinas/análise , Paladar
3.
J Agric Food Chem ; 53(5): 1713-6, 2005 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-15740063

RESUMO

Food and beverage products stored in polyethylene (PE) containers may absorb some of PE's volatile minor components and become tainted by its characteristic "plastic" odor. High-density PE containers that had imparted "plastic" odor to an experimental corn chip product were analyzed by simultaneous distillation/extraction to remove the volatile components, by gas chromatography/olfactometry (GC/O) to locate the offending components and by 2-D GC/mass spectrometry (MS) to identify the major "plastic" odor contributor (8-nonenal). The identification was made using high-resolution electron ionization and chemical ionization MS data to narrow the possibilities to two isomers of nonenal, followed by retrieval of reference spectra and confirmatory synthesis. By monitoring 8-nonenal in HDPE containers and corn chips it was demonstrated that 8-nonenal tracks with "plastic" aroma observed in containers and with "plastic" flavor observed in corn chips stored in the containers.


Assuntos
Aldeídos/análise , Embalagem de Alimentos , Odorantes/análise , Plásticos , Polietileno , Cromatografia Gasosa
4.
J Agric Food Chem ; 51(16): 4782-7, 2003 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-14705913

RESUMO

Recent findings of a potential human carcinogen, acrylamide, in foods have focused research on the possible mechanisms of formation. We present a mechanism for the formation of acrylamide from the reaction of the amino acid asparagine and a carbonyl-containing compound at typical cooking temperatures. The mechanism involves formation of a Schiff base followed by decarboxylation and elimination of either ammonia or a substituted imine under heat to yield acrylamide. Isotope substitution studies and mass spectrometric analysis of heated model systems confirm the presence of key reaction intermediates. Further confirmation of this mechanism is accomplished through selective removal of asparagine with asparaginase that results in a reduced level of acrylamide in a selected heated food.


Assuntos
Acrilamida/síntese química , Carcinógenos/síntese química , Análise de Alimentos , Temperatura Alta , Acrilamida/análise , Acrilamida/química , Asparagina/química , Carcinógenos/análise , Bases de Schiff/química , Solanum tuberosum/química
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