High-performance liquid chromatography with post-column derivatisation and fluorescence detection for sensitive determination of aflatoxin M-1 in milk and cheese

A new HPLC method with fluorescence detection using pyridinium hydrobromide perbromide as a post-column derivatising agent has been developed to determine aflatoxin M-1 in milk and cheese. The detection limits were 1 ng/kg for milk and 5 ng/kg for cheese. The calibration curve was linear from 0.001 to 0.1 ng injected. The method includes a preliminary C-18-SPE clean-up and the average recoveries of Aflatoxin M-1 from milk and cheese, spiked at levels of 25-75 ng/kg and 100-300 ng/kg, respectively, were 90 and 76%; the precision (RSDr) ranged from 1.7 to 2.6% for milk and from 3.5 to 6.5% for cheese. The method is rapid, easily automatable and therefore useful for accurate and precise screening of aflatoxin M-1 in milk and cheese. (c) 2005 Elsevier B.V. All rights reserved.[...

High content of biogenic amines in Pecorino cheeses

Pecorino refers to Italian cheeses made exclusively from raw or pasteurized ewes’ milk, characterized by a high content of fat matter and it is mainly produced in the Middle and South of Italy by traditional procedures. The autochthonous microbiota plays an important role in the organoleptic traits of Pecorino cheese and it can influence biogenic amines (BA) content. The aim of this study was to characterize from microbiological and chemical point of view 12 randomly purchased commercial cheeses produced in Abruzzo region. Moreover, the BA content and the bacteria showing a decarboxylating activity were detected. For this purpose, a real-time quantitative PCR (qPCR) was applied to evaluate histamine and tyramine-producers. The samples were well differentiated for microbial groups composition, such as aerobic mesophilic bacteria, Enterobacteriaceae, coagulase-negative staphylococci, yeasts, enterococci, mesophilic and thermophilic lactobacilli. Pathogens such as Salmonella spp., Listeria monocytogenes and Escherichia coli O157:H7 were absent in all samples. In most samples the content of BA resulted to be high, with prevalence of histamine and tyramine. In particular, total BA content reached 5861 mg/kg in Pecorino di Fossa cheese. The qPCR method resulted to be very useful to understand the role of autochthonous Pecorino cheese microbiota on BA accumulation in many different products. In fact, since the ability of microorganisms to decarboxylate aminoacids is highly variable being in most cases strain-specific, the detection of bacteria possessing this activity is important to estimate the risk of BA cheese content

Distribution of aflatoxin M1 during Grana Padano cheese production from naturally contaminated milk

The distribution of aflatoxin M1 (AFM1) has been investigated in samples of whey, curd and a typical hard and long maturing cheese like Grana Padano (ripened for twelve months), produced with naturally contaminated milk in a range of 30\u201398 ng AFM1/kg. AFM1 determinations were carried out on 25 samples of each product by reverse-phase HPLC and fluorescence detection with post-column derivatisation, after a preliminary C18-SPE clean-up. Experimental results show that, in comparison to milk, AFM1 concentration levels increased both in curd (3-fold) and in long maturing cheese (4.5-fold), while AFM1 occurrence in whey decreased by 40%. These data suggest that AFM1 concentration in milk could be a good predictor of its fate in milk products

Distribution of aflatoxin M1 during Grana Padano cheeseproduction from naturally contaminated milk

The distribution of aflatoxin M1 (AFM1) has been investigated in samples of whey, curd and a typical hard and long maturing cheese like Grana Padano (ripened for twelve months), produced with naturally contaminated milk in a range of 30–98 ng AFM1/kg. AFM1 determinations were carried out on 25 samples of each product by reverse-phase HPLC and fluorescence detection with post-column derivatisation, after a preliminary C18-SPE clean-up. Experimental results show that, in comparison to milk, AFM1 concentration levels increased both in curd (3-fold) and in long maturing cheese (4.5-fold), while AFM1 occurrence in whey decreased by 40%.[...

Ultra-Performance Liquid Chromatography-Triple Quadruple Mass Spectrometry (UPLC-TQ/MS) for Evaluation of Biogenic Amines in Wine

In this study, a fast, simple, and sensitive analytical method for direct determination of biogenic amines tryptamine, putrescine, histamine, phenylethylamine, tyramine, cadaverine, spermine, and spermidine in wine has been developed and validated. Detection of analytes was performed with ultra-performance liquid chromatography (UPLC) coupled to triple quadruple mass spectrometer (TQ/MS). The calibration curves of all amines were linear with correlation coefficients (R2) ranging from 0.9906 for putrescine to 0.9998 for histamine and 2-phenyethylamine. The accuracy of the method was checked with a standard addition method, showing good accuracy, repeatability, and reproducibility (RSD < 10%). The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.50 to 30 μg/L and 1.50 to 90 μg/L, respectively, for all amines. The validated method was applied to detect and quantify biogenic amines in Macedonian red and white wines. Higher concentration of amines was observed in red wines (5797 μg/L, on average) compared to the white wines (1485 μg/L, on average)