RESUMO
Head-space (HS) gas chromatography (GC) coupled to mass spectrometry (MS) is proposed for the assessment of the contamination of mayonnaise as an alternative to plate counting, which is the technique commonly used for evaluating microbial contamination. More specifically, this method was applied in the detection of Candida metapsilosis and Zygosaccharomyces bailii, both of great importance in term of food spoilage since they are resistant to many of the common methods of food preservation. Different chemometric models were investigated using the data obtained by GC-MS (m/z profile, area of the chromatographic peaks and entire chromatographic profile), in order to obtain the highest classification success. The best results were obtained using the chromatographic profile (success rate of 92%). Contaminated samples could also be classified according to the concentration of yeast, obtaining a success rate of 87.5%. Finally, a chemometric model was constructed in an attempt to differentiate between strains.
Assuntos
Condimentos/microbiologia , Microbiologia de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Candida parapsilosis/isolamento & purificação , Conservação de Alimentos/métodos , Zygosaccharomyces/isolamento & purificaçãoRESUMO
We established a simple, sensitive, and reproducible method to analyze the histamine and tyramine levels in Japanese soy sauce and its mash (called moromi) using hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Histamine and tyramine quantification was performed using their stable isotopes for electrospray ionization-tandem mass spectrometry in the selected reaction monitoring mode. The sample pretreatment process was a simple, one-step liquid-liquid extraction. HILIC separation was performed with a gradient elution of aqueous ammonium formate and acetonitrile. Because of validation tests, the linearity, the accuracies, and precisions were sufficient. The limit of detection and the limit of quantification were 0.09 and 0.29 ppm for histamine and 0.13 and 0.42 ppm for tyramine, respectively. We successfully applied this method to histamine and tyramine determination in four kinds of commercial Japanese soy sauces and also in moromi samples during soy sauce production.
Assuntos
Condimentos/análise , Manipulação de Alimentos , Inspeção de Alimentos/métodos , Histamina/análise , Alimentos de Soja/análise , Tiramina/análise , Condimentos/economia , Condimentos/microbiologia , Fermentação , Indústria de Processamento de Alimentos/economia , Histamina/análogos & derivados , Resíduos Industriais/análise , Resíduos Industriais/economia , Japão , Limite de Detecção , Reprodutibilidade dos Testes , Alimentos de Soja/economia , Alimentos de Soja/microbiologia , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Fatores de Tempo , Tiramina/análogos & derivadosRESUMO
The 3-monochloro-1,2-propandiol (3-MCPD) levels in soy sauces which contained hydrolysed vegetable protein were evaluated for the Bulgarian market. For analysis of 3-MCPD, a gas chromatography-mass spectrometry (GC-MS) method was applied with a linear range of 0.03-2.00 µg mL⻹ and a limit of detection (LOD) of 2.3 µg kg⻹ and a limit of quantification (LOQ) of 3.4 µg kg⻹. At these levels, the standard deviation was 5.1%, with recoveries between 81% and 102%. The method was applied to the analysis of 21 samples of soy sauce from the Bulgarian market. Results ranged from 3.7 to 185.6 µg kg⻹. Soy sauces produced from hydrolysed soy protein contained higher levels of 3-MCPD than naturally fermented sauces. In 38.4% of samples of Bulgarian origin, the 3-MCPD content was above the EU limit of 20 µg kg⻹. In all analysed samples, 33.3% had a 3-MCPD content above the EU limit.
Assuntos
Condimentos/análise , Contaminação de Alimentos , Inspeção de Alimentos/métodos , Alimentos de Soja/análise , alfa-Cloridrina/análise , Métodos Analíticos de Preparação de Amostras , Bulgária , Condimentos/economia , Condimentos/microbiologia , Condimentos/normas , Dieta/etnologia , União Europeia , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Fidelidade a Diretrizes , Política de Saúde , Promoção da Saúde , Humanos , Limite de Detecção , Hidrolisados de Proteína/química , Hidrolisados de Proteína/metabolismo , Hidrolisados de Proteína/normas , Reprodutibilidade dos Testes , Extração em Fase Sólida , Alimentos de Soja/economia , Alimentos de Soja/microbiologia , Alimentos de Soja/normas , Proteínas de Soja/química , Proteínas de Soja/metabolismo , Proteínas de Soja/normas , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Ethyl carbamate (EC) in wine, grain spirits and wine sauce (145 samples) was analysed using solid-phase extraction and stable isotope dilution GC/MS. Samples were obtained from markets in eight areas (Shijiazhuang, Baoding, Handan, Qinhuangdao, Langfang, Zhangjiakou, Xingtai and Cangzhou) of Hebei Province, China. The method had a limit of detection of 2 µg kg⻹, with recoveries varying from 95.7 to 102% and RSD ranging 2.3-5.6%. The average concentrations of ethyl carbamate in wines, grain spirits and wine sauce were 14.7 (<2.0-44.5) µg kg⻹, 33.8 (2.9-129) µg kg⻹ and 8.7 (<2.0-63.3) µg kg⻹, respectively. The results led to the development of limit standards that can be used to predict the concentration of ethyl carbamate in Chinese fermented wines.