L. La Pera

Influence of roasting and different brewing processes on the ochratoxin A content in coffee determined by high-performance liquid chromatography-fluorescence detection (HPLC-FLD)

A rapid and reliable procedure has been developed for the determination of ochratoxin A (OTA) in green and roasted coffee. The method consists of extraction of the sample with methanol–5% aqueous sodium hydrogen carbonate/1% PEG8000 (20:80), followed by immunoaffinity column (IAC) clean-up and, finally, high-performance liquid chromatography (HPLC) determination with fluorimetric detection. Mean recoveries for green and roasted coffee spiked at different levels ranging from 94 and 105% were obtained. The limit of determination (S/N = 3) was 0.032 ng g−1 and the precision (within-laboratory relative standard deviation) was 6%. The method described has been used to assess the influence of roasting and different brewing processes on OTA content in commercial lots of green and roasted coffee. The results provided evidence that roasting led to a significant drop on OTA levels (65–100%). Also, the way coffee is prepared affects the OTA content: brewing using a Moka Express (Italian coffee) led to a significant reduction of OTA concentration (50–75%) since hot water stays in contact with coffee for a short time. On the contrary, Turkish coffee-making (infusion for about 10 min) cause poor reduction in OTA.

Statistical study of the influence of fungicide treatments (mancozeb, zoxamide and copper oxychloride) on heavy metal concentrations in Sicilian red wine

The aim was to assess the influence of mancozeb, zoxamide and copper oxychloride fungicide treatments on Mn, Zn, Cu, Cd and Pb concentrations in Sicilian red wines, grapes, marcs and grape stalks. The experimentation was carried out over two crop years: 2003 and 2004. Trace metals analysis was performed by derivative stripping chronopotentiometry, which allowed detection of concentrations lower than 1 ng g−1. The data obtained gave evidence that the levels of Mn and Zn in wines from plots treated with zoxamide–mancozeb were about threefold higher than those observed in the control. Wines treated with Cu oxychloride had a significant increase in Cu(II) concentrations with respect to the control; in particular, samples from 2004 showed a 50% increase in Cu levels. Furthermore, as shown in a previous paper, the fungicides treatments studied led to a moderate increase in Pb(II) and Cd(II) levels in treated samples with respect to the control. Wines from 2004 had higher Cu and Pb amounts than wines from 2003; but the concentrations of all the other metals were similar. Statistical analysis of the data by linear discriminant analysis (LDA) and the Kruskal–Wallis test confirmed that both zoxamide–mancozeb treatments and copper oxychloride treatments exerted a significant influence on Mn(II), Zn(II) Cu(II), Pb(II) and Cd(II) concentrations in wines, grapes, marcs and grape stalks samples from both the studied vintages.

Determination of copper, zinc, selenium, lead and cadmium in potatoes (Solanum tuberosum L.) using potentiometric stripping methods

Potentiometric stripping analysis was used to determine simultaneously the content of zinc(II), cadmium(II), lead(II) and copper(II) in potatoes, whereas the concentration of selenium was determined by cathodic stripping potentiometric analysis. Metal cations were extracted from potatoes by hydrogen peroxide/hydrochloric acid treatments. The relative standard deviation of the methods ranged from 2.3 to 4.1% and the detection limits were lower than 2.5 μg kg−1. The results obtained with the proposed methods were compared with those obtained with graphite furnace atomic absorption spectroscopy, a common method for determining metals. The results of the two methods agreed to within 6.1%. Twelve samples of yellow flesh potatoes from different cultivars were analysed. Of all the metals determined, Cu and Zn were the most abundant with concentrations between 0.5 and 4.6 mg kg−1. Selenium was only found in three samples in very low amounts (<0.1 mg kg−1), whilst Pb and Cd concentrations were in the range 0.01 − 0.27 mg kg−1.