Aftab Ahmed

Aflatoxins contamination and prevention in red chillies (Capsicum annuum L.) in Pakistan

During 2006–2011, 331 red chilli samples (226 whole, 69 powdered and 36 crushed) were collected from all over Pakistan for the estimation of total aflatoxins (AFs = AFB1 + AFB2 + AFG1 + AFG2) contamination by thin layer chromatography (TLC). Mean AFs levels in whole, powdered and crushed chillies were 11.7, 27.8 and 31.2 µg kg−1, respectively. AFs levels in 62.4% of whole, 26.1% of powdered and 19.4% of crushed chillies were found lower than the maximum limit (ML = 10 µg kg−1) as assigned by the European Union. Furthermore, whole (27.9%), powdered (28%) and crushed (27.8%) chillies showed AFs contamination which ranged between 10 and 20 µg kg−1. However, 9.7% of whole, 46% of powdered and 52.8% of crushed chillies showed AFs levels beyond the ML of 20 µg kg−1 as assigned by the USDA. It was concluded that AFs contamination in chillies requires further investigation, monitoring and routine analysis. Furthermore, proper harvesting, drying, handling, storage and transport conditions need to be employed.

Development and validation of a high-performance liquid chromatography method with post-column derivatization for the detection of aflatoxins in cereals and grains

A novel, reliable and rapid high-performance liquid chromatography (HPLC) method with post-column derivatization was developed and validated. The HPLC method was used for the simultaneous determination of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) in various cereals and grains. Samples were extracted with 80:20 (v/v) methanol:water and purified using C18 (40–63 μm) solid-phase extraction cartridges. AFs were separated using a LiChroCART–RP-18 (5 μm, 250 × 4.0 mm2) column. The mobile phase consisted of methanol:acetonitrile:buffer (17.5:17.5:65 v/v) (pH 7.4) delivered at the flow rate of 1.0 mL min−1. The fluorescence of each AF was detected at λex = 365 nm and λem = 435 nm. All four AFs were properly resolved within the total run time of 20 min. The established method was extensively validated as a final verification of the method development by the evaluation of selectivity (AFB1, AFB2, AFG1 and AFG2), linearity (R2 ≥ 0.9994), precision (average SD ≤ 2.79), accuracy (relative mean error ≤ −5.51), robustness (p < 0.0080), ruggedness (p < 0.0100) and average recoveries (89.2–97.8%). The limits of quantification of AFB1, AFB2, AFG1 and AFG2 were 0.080, 0.073, 0.062 and 0.066 ng g−1, respectively. Finally, the developed method was applied for the analysis of AFs in 45 samples comprising rice (n = 20), wheat (n = 15) and maize (n = 10). The results showed that 65% of rice, 20% of wheat and 80% of maize samples were found contaminated with AFs. Thus, according to the achieved results, it is suggested that the newly developed HPLC method could be effectively applied for the routine analysis of the AFs in different cereals and grains.

Aflatoxins contamination in Pakistani brown rice: a comparison of TLC, HPLC, LC-MS/MS and ELISA techniques.

Abstract Advancement in the field of analytical food-chemistry has explored various experimental techniques for aflatoxins (AFs) quantification. The present study was aimed to compare four different techniques; thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), liquid chromatography–tandem mass spectrometry (LC–MS/MS) and enzyme-linked immunosorbent assay (ELISA) for the analysis of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) in brown rice (n = 120) being collected from Karachi, Pakistan. All the four assays provide precised, accurate and comparable results. However, some differences were observed. For instance, TLC, HPLC and LC–MS/MS methodologies offered the advantage of the quantification of individual toxins in contrast to ELISA technique. The contamination ranges of AFB1/AFB2 as determined by TLC, HPLC and LC–MS/MS were 1.18–9.97/0.59–1.52, 0.16–10.54/0.26–1.35 and 0.11–10.88/0.38–1.48 µg/kg, respectively. However, AFG1 and AFG2 were not detected in any tested samples. Furthermore, owing to low-detection limit and sensitivity, HPLC and LC–MS/MS methodologies have identified greater number of contaminated samples in comparison to TLC and ELISA techniques. The overall average results of total AFs as provided by HPLC (3.79 µg/kg) and LC–MS/MS (3.89 µg/kg) were found higher in comparison to TLC (3.68 µg/kg) and ELISA (3.70 µg/kg). On the basis of achieved results, it was concluded that TLC, HPLC, LC–MS/MS and ELISA techniques are valuable tool for the quantification of AFs in cereals and grains. Furthermore, HPLC and LC–MS/MS techniques offer an added advantage for the detection of AFs in diminutive levels.

Aflatoxins and ochratoxin A in export quality raisins collected from different areas of Pakistan

ABSTRACT During 2012–2014, 170 samples of export quality raisins were collected from different vendors in Pakistan. The collected samples were analysed for the presence of aflatoxins (AFs) and Ochratoxin A (OTA) contamination using high-performance liquid chromatography technique. The limit of detection and limit of quantification of AFs/OTA were 0.12/0.10 and 0.36/0.30 µg kg−1, respectively. Only 5% of the samples were contaminated with AFs, ranging 0.15–2.58 µg kg−1 with a mean of 0.05 ± 0.26 µg kg−1. None of the raisin samples exhibited AFs contamination above the maximum limit (ML = 4 µg kg−1) as set by the European Union (EU). About 72% of the samples were contaminated with OTA, ranging 0.14–12.75 µg kg−1 with a mean of 2.10 ± 1.9 µg kg−1. However, in 95.3% of the tested samples, OTA level was lower than the ML of 10 µg kg−1 as regulated by the EU. Apparently, a strict and continuous monitoring plan, including regulatory limits, improves food safety and quality for all types of commodities.

Aflatoxins in composite spices collected from local markets of Karachi, Pakistan

ABSTRACT This survey was carried out to evaluate the occurrence of total aflatoxins (AFs; B1+B2+G1+G2) in unpacked composite spices. A total of 75 samples of composite spices such as biryani, karhai, tikka, nihari and korma masalas were collected from local markets of Karachi, Pakistan, and analysed using HPLC technique. The results indicated that AFs were detected in 77% (n = 58) samples ranging from 0.68 to 25.74 µg kg−1 with a mean of 4.63 ± 0.95 µg kg−1. In 88% (n = 66) samples, AFs level was below the maximum limits (ML = 10 µg kg−1) as imposed by EU. Furthermore, 61% (n = 46) tested samples contained AFs level between 1 and 10 µg kg−1, 9% (n = 7) exhibited AFs contamination ranged 10−20 µg kg−1 and only 3% (n = 2) of the investigated samples contained AFs levels higher than the ML of 20 µg kg−1 for total aflatoxins as set by the USA. It was concluded that there is need to establish a strict and continuous national monitoring plan to improve safety and quality of spices in Pakistan.

Aflatoxin M1 in fresh milk collected from local markets of Karachi, Pakistan

ABSTRACT During 2016–2017, 156 samples of fresh milk samples were collected from local markets of Karachi, Pakistan and analysed for aflatoxin M1 (AFM1) contamination using ELISA technique. AFM1 was detected in 143 (91.7%) samples, ranged from 20 to 3090 ng L−1 with a mean level of 346.2 ng L−1. In 125 (80.1%) samples, the AFM1 contamination was greater than the maximum limit (ML = 50 ng L−1) set by EU. However, in 51 (32.7%) samples, the AFM1 level was higher than the ML of 500 ng L−1 as assigned by the USA. Statistical analysis showed that the AFM1 level in milk samples from summer was significantly (p < 0.05) higher than that obtained in winter. It was concluded that the AFM1 levels in the tested samples appear to be a serious public health problem. Therefore, immediate measures should be taken and re-evaluation done for the procedures for farming, transportation, refrigeration, and storage for the control of AFM1 level in milk samples.

Aflatoxin B1 in betel nuts (Areca catechu L.) imported to Pakistan from different regions of South Asia

Aflatoxin B1 (AFB1) levels were evaluated in betel nuts (Areca catechu L.) being imported to Pakistan during 2010–2011. In total, 278 betel nut samples (India = 21, Indonesia = 51, Sri-Lanka = 34 and Thailand = 172) were received from the Department of Customs and were analysed by thin layer chromatography (TLC). All Indian origin betel nuts showed AFB1 contamination ranging from 11.7–262.0 µg kg−1 with a mean of 92.5 µg kg−1. Among Indonesian and Sri Lankan shipments, 80.4% and 73.5% betel nuts were contaminated with AFB1 ranging between 3.3–39.2 and 6.5–103.4 µg kg−1 with a mean of 11.6 and 35.0 µg kg−1, respectively. However, only 30.2% of Thailand origin samples showed AFB1 contamination ranging 3.3–77.0 µg kg−1 with a mean of 6.6 µg kg−1. The widespread occurrence of AFB1 increases the hazard associated with betel nuts. Thus, strict control is a pre-requisite for the production and import/export of psychoactive substances as betel nuts.