Silvia Rastelli

Evaluation and Improvement of Extraction Methods for the Analysis of Aflatoxins B1, B2, G1 and G2 from Naturally Contaminated Maize

The extraction procedure for aflatoxin determination in maize is based on a methanol–water (8 + 2 v/v) or an acetone–water (85 + 15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Different results were obtained for highly contaminated maize: significantly higher levels of aflatoxin B1 were obtained by acetone–water, on the contrary higher levels of aflatoxin G2 were achieved by methanol–water. Then, acetone–water mixtures in different proportions (7 + 3, 6 + 4 and 5 + 5 v/v) were tested to improve the extraction of aflatoxin G2. Applying these extraction mixtures, the values both of aflatoxin B1 and of other aflatoxins were generally higher compared to those obtained by acetone–water 85 + 15; moreover, acetone–water (6 + 4) and (7 + 3) showed the best extraction efficiency for all aflatoxins.

Ochratoxin A and Aflatoxins in liquorice products

The occurrence of ochratoxin A (OTA) and aflatoxins (AFs) in liquorice products made in Italy was surveyed. Twenty-eight samples of dried liquorice extract and fifty-four of liquorice confectionery (liquorice content between 2 and 10%) were collected from retail outlets located in northern Italy. After extraction and purification through an immunoaffinity column, OTA and AFs were analysed using both HPLC-FLD and HPLC-MS/MS. OTA occurred in all samples of dried liquorice extract and in 61% of samples of liquorice confectionery, showing very high values for the former (mean 89.6 µg kg-1, maximum value 990.1 µg kg-1), and relatively low levels for the latter (mean 0.96 µg kg-1, maximum value 8.3 µg kg-1). The contribution of dried liquorice extract to OTA intake appears to be non-negligible for children, who are potentially high consumers. AF contamination resulted very low: AFB1 was detected only in 15.8% of samples (maximum value 7.7 µg kg-1, mean 0.38 and 0.41 µg kg-1 for dried liquorice extract and liquorice confectionery, respectively); the other AFs were not detected. To our knowledge, it is the first time that AFB1 has been detected in liquorice extract samples.

Enzyme-assisted extraction for the HPLC determination of ochratoxin A in pork and dry-cured ham.

The extraction of ochratoxin A from meat products is generally carried out using chlorinated organic solvents, such as chloroform or methyl chloride, acidified with hydrochloric or o-phosphoric acid. In this study, an innovative method was developed to extract ochratoxin A from pork and dry-cured ham samples. The method was based on an enzyme-assisted extraction with pancreatin in phosphate buffer pH 7.5. Pancreatin hydrolyses the proteins, so that ochratoxin A, kept in the ionised form, is easily extracted by the aqueous solution. After purification through an immunoaffinity column, ochratoxin A is determined by HPLC with fluorescence detection. The average recovery values were higher than 90.0% and the relative standard deviations were below 5.5%. The limits of detection and of quantification were 0.06 and 0.12 µg kg−1, respectively. A comparison between the new enzyme-assisted extraction and an established chloroform method was carried out on six naturally contaminated samples of pork and on 40 samples of dry-cured ham. Significantly higher (p < 0.001) values of ochratoxin A were obtained on dry-cured ham samples by the enzyme-assisted method.

Sterigmatocystin Occurrence in Paddy and Processed Rice Produced in Italy in the Years 2014–2015 and Distribution in Milled Rice Fractions

The occurrence of sterigmatocystin (STC) in paddy and processed rice samples produced in Italy was surveyed. After extraction and purification, STC was analysed using HPLC-MS/MS. STC was detected in all paddy rice samples (n = 49), in the range 0.29–15.85 μg·kg−1. As regards processed rice, a widespread contamination was found in brown and parboiled rice. All the brown rice samples were contaminated between 0.12 and 1.32 μg·kg−1; for parboiled rice, the incidence was 90.9% and the maximum level was 1.09 μg·kg−1. The contamination in white rice was significantly lower (p < 0.01). The STC distribution in different rice fractions, obtained by the de-hulling and polishing processes, was evaluated. After de-hulling, the STC percentage remaining in brown rice was in the range 21.2%–30.8%. The polishing process, from brown to white rice, caused another remarkable decrease of contamination; the STC remaining in white rice was 2.2%–8.3% of the amount found in paddy rice.

Survey on acrylamide in roasted coffee and barley and in potato crisps sold in Italy by a LC–MS/MS method

ABSTRACT A survey on the occurrence of acrylamide (AA) in roasted coffee, barley, and potato crisps was carried out using an intra-lab validated liquid chromatography (LC)–MS (mass spectrometry)/MS method. Over the years 2015–2016, 66 samples of coffee, 22 of roasted barley, and 22 of potato crisps were collected from retail outlets in Italy. AA was detected in almost all samples. In roasted coffee, the level exceeded 450 µg kg−1, the limit recommended by the European Commission (EC), in 36.4% of the samples. In roasted barley, mean contamination was slightly lower than in coffee and no sample exceeded the EC limit of 2000 µg kg−1. The AA contamination in potato crisps was remarkable. A percentage of 36.4 (n = 8) showed a value higher than the EC limit of 1000 µg kg−1. Considering the average consumption of coffee and potato crisps by Italian people, AA exposure is significant and should be decreased.

Mitigation measures for acrylamide reduction in dough-based potato snacks during their expansion by frying

ABSTRACT Acrylamide (AA) can occur in fried and baked food products which contain reducing sugars and free asparagine. Recently, the European Commission established mitigation measures and benchmark levels for the reduction of AA in food. The content of reducing sugars in raw materials and the temperature and time of the expansion process by frying were considered in this study of the preparation of dough-based potato snacks, mainly destined for children. Final moisture and bulk density were also evaluated. An increase from 0.15 to 1.0% in reducing sugar content, due to the addition of micro-ingredients in the dough, caused a remarkable AA increase of five- to six-fold. During frying at temperatures between 175 and 195°C, AA was produced after only a few seconds; the AA content was affected more by process time than by temperature. The best temperature/time conditions for expansion by frying were 185°C for 8 s.