Current Developments of Analytical Methodologies for Aflatoxins' Determination in Food during the Last Decade (2013-2022), with a Particular Focus on Nuts and Nut Products

Prevalence and concentration of aflatoxin M1 in milk and dairy products: an umbrella review of meta-analyses

BACKGROUND

Aflatoxin M1 (AFM1) is a derivative of aflatoxin B1 and a significant contaminant of milk and dairy products. In this study, we implemented an umbrella review of all existing systematic reviews and meta-analyzing studies to apprise and summarize the worldwide prevalence and level of AFM1 in milk and dairy products.

METHODS

We conducted a systematic review of structured review and meta-analysis articles published in English until January 2024, with no time limit. Articles were sourced from reputable databases, including PubMed/MEDLINE, EMBASE, Scopus, Web of Science, CINAHL and the Cochrane Database of Systematic Reviews. Relevant studies from Google Scholar were also included.

RESULTS

The overall prevalence of AFM1 in all dairy products was 66.2% (95% CI 60.6 to 71.9%), with high heterogeneity (I²=99.7%, Q statistic=2221.03, p<0.0001). The prevalence for specific dairy products was as follows: raw milk, 64.8% (95% CI 60.9 to 68.7%); pasteurized milk, 88.7% (95% CI 81.6 to 95.7%); sterilized milk, 71.0% (95% CI 67.2 to 74.8%); ultra-high temperature processing (UHT) milk, 67.9% (95% CI 64.9 to 70.9%); yogurt, 58.8% (95% CI 42.5 to 75.1%); doogh, 17.2% (95% CI 13.9 to 20.5%); and cheese 49.8% (95% CI 47.8 to 51.9%). The overall mean concentration of AFM1 across all dairy products was 57.22 ng/kg (95% CI 46.95 to 67.49), with significant heterogeneity (I²=99.7%, Q statistic=2221.03, p<0.0001). Mean AFM1 levels (ng/kg) for each dairy product were as follows: raw milk, 52.51 (95% CI 40.96 to 64.05); pasteurized milk, 71.14 (95% CI 48.81 to 93.47); sterilized milk, 60.10 (95% CI 30.90 to 89.30); UHT milk, 82.57 (95% CI 35.30 to 129.85); yogurt, 46.74 (95% CI 24.27 to 69.21); and doogh, 41.60 (95% CI 32.60 to 50.60).

CONCLUSIONS

In total, these results highlight the importance of increasing the regulation of animal feed, reducing aflatoxin B1 (AFB1) in animal feed, and monitoring AFM1 in dairy products, particularly raw and heated milk.

Elastin-like polypeptide-functionalized nanobody for column-free immunoaffinity purification of aflatoxin B1

A column-free immunoaffinity purification (CFIP) technique for sample preparation of aflatoxin B1 (AFB1) was developed using an AFB1-specific nanobody (named G8) and an elastin-like polypeptide (ELP). The reversible phase transition between liquid and solid in response to temperature changes was exhibited by the ELP which was derived from human elastin. The G8 was tagged with ELPs of various lengths (20, 40, 60, and 80 repeat units) at the C-terminus using recursive directional ligation (RDL). Coding sequences were then subcloned into pET30a at the multiple cloning sites. Bioactive recombinant proteins were produced by expressing them as inclusion bodies in Escherichia coli BL21 (DE3), then dissolved and refolded. Analysis by indirect competitive enzyme-linked immunosorbent assay (icELISA) and transition temperature (Tt) measurement confirmed that the refolded G8-ELPs preserved the ability to recognize AFB1 as well as phase transition when the temperature rose above Tt. To establish the optimal conditions for cleaning AFB1, the effects of various parameters on recovery were investigated. The recovery in ELISA tests was 95 ± 3.67% under the optimized CFIP workflow. Furthermore, the CFIP-prepared samples were applied for high-performance liquid chromatography (HPLC) detection. The recovery in the CFIP-HPLC test ranged from 54 ± 1.86% to 98 ± 3.58% for maize, rice, soy sauce, and vegetable oil samples. To the best of our knowledge, this is the first report combining the function of both nanobody and ELP to develop a cleanup technique for small molecules in a complex matrix. The CFIP for the sample pretreatment was easy to use and inexpensive. In contrast to conventional immunosensitivity materials, the reagent utilized in the CFIP was entirely biosynthesized without any chemical coupling reactions. This suggests that the nanobody-ELP may serve as a useful dual-functional reagent for the development of sample cleaning or purification methods.

Optimization and Validation of a Cheaper, Safer, and More Sustainable Methodology for Aflatoxins Determination in Rich-Lipidic Matrices (Pistachio Nuts) Using Deep Eutectic Solvent Extraction and UHPLC-FLD Analysis

Aflatoxins pose a major health concern and require strict monitoring in food products. Existing methods rely on hazardous organic solvents for extraction, prompting the development of a greener alternative. This study explores deep eutectic solvents (DESs) for aflatoxin extraction from pistachios, a valuable food product prone to aflatoxin contamination. The proposed method utilizes DES extraction followed by solid-phase extraction cleanup and ultrahigh-performance liquid chromatography coupled with fluorescence detector analysis. Recovery rates ranged from 85.5 to 99.1% for pistachios spiked with 1-8 ng/g aflatoxins, in compliance with EU regulations, with coefficients of variation less than 2.94%. The method demonstrates good sensitivity with limits of detection and quantification in the range of 0.02-0.22 ng/g and 0.05-0.72 ng/g, respectively. Greenness assessment using AGREEPrep and White Analytical Chemistry metrics confirms its environmental sustainability. This approach offers a promising, safer, and more eco-friendly alternative for aflatoxin extraction from complex food matrices like pistachios.

Determination and risk assessment of aflatoxin B1 in the kernel of imported raw hazelnuts from Eastern Azerbaijan Province of Iran

Aflatoxin B1 (AFB1) is widespread and seriously threatens public health worldwide. This study aimed to investigate AFB1 in imported hazelnut samples in northwest of Iran (Eastern Azerbaijan Province) using High-Performance Liquid Chromatography with a Fluorescent Detector (HPLC-FLD). In all tested samples AFB1 was detected. The mean concentration of AFB1 was 4.20 μg/kg and ranged from 3.145 to 8.13 μg/kg. All samples contained AFB1 levels within the maximum acceptable limit except for one sample. Furthermore, the human health risk assessment of AFB1 from consuming imported hazelnuts by Iranian children and adults was evaluated based on the margin of exposure (MoE) and quantitative liver cancer risk approaches. The MoE mean for children was 2529.76, while for adults, it was 8854.16, indicating a public health concern. The present study found that the risk of developing liver cancer among Iranian children was 0.11100736 per 100,000 people, and in the Iranian adult population was 0.0314496 cancers per 100,000 people. Since environmental conditions potentially affect aflatoxin levels in nuts, countries are advised to monitor aflatoxin contents in imported nuts, especially from countries with a conducive climate for mold growth.

Aflatoxins: Occurrence, biosynthesis, mechanism of action and effects, conventional/emerging detection techniques

Aflatoxins (AFs) are toxic secondary metabolites prevalent in various food and agricultural products, posing significant challenges to global food safety. The detection and quantification of AFs through high-precision analytical techniques are crucial in mitigating AF contamination levels and associated health risks. Variousmethods,including conventional and emerging techniques, have been developed for detecting and quantifyingAFsinfood samples. This review provides an in-depth analysis of the global occurrence of AF in food commodities, covering their biosynthesis, mode of action, and effects on humans and animals. Additionally, the review discusses different conventional strategies, including chromatographic and immunochemical approaches, for AF quantification and identification in food samples. Furthermore, emerging AF detection strategies, such as solid-state gas sensors and electronic nose technologies, along with their applications, limitations, and future perspectives, were reviewed. Sample purification, along with their respective advantages and limitations, are also discussed herein.