A Novel Dispersive Nanomagnetic Particle Solid-Phase Extraction Method to Determine Aflatoxins in Nut and Cereal Samples

Aflatoxins in the rice production chain: A review on prevalence, detection, and decontamination strategies

Rice (Oryza sativa L.) is one of the most consumed cereals that along with several important nutritional constituents typically provide more than 21% of the caloric requirements of human beings. Aflatoxins (AFs) are toxic secondary metabolites of several Aspergillus species that are prevalent in cereals, including rice. This review provides a comprehensive overview on production factors, prevalence, regulations, detection methods, and decontamination strategies for AFs in the rice production chain. The prevalence of AFs in rice is more prominent in African and Asian than in European countries. Developed nations have more stringent regulations for AFs in rice than in the developing world. The contamination level of AFs in the rice varied at different stages of rice production chain and is affected by production practices, environmental conditions comprising temperature, humidity, moisture, and water activity as well as milling operations such as de-husking, parboiling, and polishing. A range of methods including chromatographic techniques, immunochemical methods, and spectrophotometric methods have been developed, and used for monitoring AFs in rice. Chromatographic methods are the most used methods of AFs detection followed by immunochemical techniques. AFs decontamination strategies adopted worldwide involve various physical, chemical, and biological strategies, and even using plant materials. In conclusion, adopting good agricultural practices, implementing efficient AFs detection methods, and developing innovative aflatoxin decontamination strategies are imperative to ensure the safety and quality of rice for consumers.

Cu-nanoparticles@ graphene nanocomposite: A robust and efficient nanocomposite for micro-solid phase extraction of trace aflatoxins in different foodstuffs

Cu-nanoparticles-immobilized graphene (Cu@G) nanocomposite was fabricated in this study by reducing Cu(II) ions in the presence of graphene oxide using a simple chemical reduction step. Cu@G nanocomposite was applied as a sorbent for the SPE of four aflatoxins (AFs). A reusable syringe was filled with the fabricated nanocomposite and used as a sorbent for the micro-solid phase extraction of four AFs (AFB1, AFB2, AFG1, AFG2). The impact of different analytical factors was fully investigated and optimized. Excellent recoveries, ranging from 92.0 to 108.5 %, were detected when evaluating target AFs in samples of rice, maize, and pistachio. The LOD, LOQ, and linear ranges were attained under optimal circumstances in the ranges of 0.0062 µg kg-1, 0.0192 µg kg-1, and 0.0-20 µg kg-1, respectively. The discovered approach provided the dual benefits of a high enrichment capability of Cu-nanoparticles via AFs complexation and a huge porosity of graphene sheets.

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

This review aims to provide a clear overview of the most important analytical development in aflatoxins analysis during the last decade (2013-2022) with a particular focus on nuts and nuts-related products. Aflatoxins (AFs), a group of mycotoxins produced mainly by certain strains of the genus Aspergillus fungi, are known to impose a serious threat to human health. Indeed, AFs are considered carcinogenic to humans, group 1, by the International Agency for Research on Cancer (IARC). Since these toxins can be found in different food commodities, food control organizations worldwide impose maximum levels of AFs for commodities affected by this threat. Thus, they represent a cumbersome issue in terms of quality control, analytical result reliability, and economical losses. It is, therefore, mandatory for food industries to perform analysis on potentially contaminated commodities before the trade. A full perspective of the whole analytical workflow, considering each crucial step during AFs investigation, namely sampling, sample preparation, separation, and detection, will be presented to the reader, focusing on the main challenges related to the topic. A discussion will be primarily held regarding sample preparation methodologies such as partitioning, solid phase extraction (SPE), and immunoaffinity (IA) related methods. This will be followed by an overview of the leading analytical techniques for the detection of aflatoxins, in particular liquid chromatography (LC) coupled to a fluorescence detector (FLD) and/or mass spectrometry (MS). Moreover, the focus on the analytical procedure will not be specific only to traditional methodologies, such as LC, but also to new direct approaches based on imaging and the ability to detect AFs, reducing the need for sample preparation and separative techniques.

Polydopamine-coated magnetic Spirulina nanocomposite for efficient magnetic dispersive solid-phase extraction of aflatoxins in pistachio

An efficient adsorbent was synthesized and used in magnetic dispersive solid phase extraction (MDSPE) of aflatoxins B1, B2, G1, and G2 at trace levels in pistachio prior to analysis by HPLC equipped with a fluorescence detector. Spirulina (Sp) algae was first magnetized, followed by surface modification with dopamine (Dp). The adsorbent was characterized using FT-IR, XRD, FE-SEM, EDX, VSM, and BET analyses. The effects of different analytical parameters on the extraction performance were evaluated. Under optimal conditions, good limits of detection (LODs) and quantifications (LOQs) were achieved in the ranges of 0.02-0.07 and 0.06-0.21 ng g^-1, respectively. The RSDs were 5.9, 6.3, 5.6, and 7.3% for AFB1, G1, B2, and G2, respectively. The proposed method was successfully used to determine AFs in pistachio samples and acceptable recoveries in the range of 72-95% were obtained.

[Progress of sample preparation and analytical methods of dried fruit foods]

坚果、果脯等干果类食品含有丰富的营养成分,深受国内外广大消费者的喜爱。但这些食品在果实生产、加工、储运时会使用农药或产生霉变等,造成干果中农药、重金属、霉菌毒素或添加剂等有害成分残留,甚至超过国家限量要求,带来严重的食品安全问题。因此,加强干果类食品的质量监督具有重要的经济和社会意义。但干果类食品基质复杂,有害物质种类多,结构和性质差异大,含量低,其分析检测需要快速高效的样品前处理技术和准确灵敏的分析检测方法。该文主要综述了近十年来干果类食品中有害物质的样品前处理及分析检测方法研究进展。其中样品前处理方法主要包括各种场辅助萃取法、相分离法和衍生化萃取方法等。场辅助萃取法主要是借助超声波和微波场等外场(协同)作用加快干果中有害物质的溶出速度,提高其萃取效率。相分离法,包括固相(微)萃取、分散固相萃取和液相(微)萃取法等,具有溶剂消耗少、分离富集效率高的优势,是干果样品分析中较常使用的前处理方法。该文还重点介绍了干果中各类有害成分分析检测技术,主要包括色谱、原子光谱、无机质谱、电化学分析等常规实验室方法,以及一些适用于现场分析的快速检测技术,并以此为基础,展望了干果类食品中有害物质分析检测技术的发展趋势。

Aflatoxin, microbial contamination, sensory attributes, and morphological analysis of pistachio nut coated with methylcellulose

Pistachio is a nut with high consumption that could be affected by aflatoxin contamination, which affects the consumption market; therefore, broad studies seem to be necessary for this area. In the current study, pistachio nuts (Abbasali variety) were coated with different concentrations (0.1%, 0.5%, 1%, and 2%) of methylcellulose (MC) by immersion method and then stored in the incubator (25°C) for four months. The inhibitory effect of hydrocolloid coating on microbial (mold, yeast, and total count) and aflatoxin (B1, B2, G1, G2, and total aflatoxin) contamination, as well as sensory attributes (flavor, color, crispiness, aroma, and total acceptability), was investigated during storage periods. Results showed that the storage period had a significant effect on yeast, mold, and total count. HPLC analysis results showed that coating with MC had a significant inhibitory effect on aflatoxin contamination, and the highest amount of aflatoxin contamination was related to the control sample (3.5%). All samples except sample coated with MC 0.5% had appropriate total acceptability. Regarding the inhibitory effect of MC edible coating on aflatoxin contamination, its application on pistachio nut could be a promising approach to control the fungus infection and reduce aflatoxin production in coated pistachio.

Synthesised magnetic nano-zeolite as a mycotoxins binder to reduce the toxicity of aflatoxins, zearalenone, ochratoxin A, and deoxynivalenol in barley

Agricultural commodities, particularly cereals can be contaminated with mycotoxins during the pre- and post-harvest stage. The main goal of this study was to evaluate the efficacy of magnetic zeolite nanocomposite (MZNC) as an adsorbent for the reduction of mycotoxins in barley flour. The MZNC is synthesised using an eco-friendly and efficient procedure and characterised by zeta potential, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The adsorbent amount that affects the adsorption capacity was optimised. Low amounts of the nanocomposite removed >99% of aflatoxins, 50% of ochratoxin A, 22% of zearalenone, and 1.8% of the deoxynivalenol from the contaminated sample and adsorption by MZNC was better than the natural zeolite; this phenomenon is related to the wide surface of nanocomposites. Results provide new insights into possible future research that could overcome the challenges of using nanotechnology to eliminate mycotoxins from agricultural products. It can be hoped that the presence of cheap and eco-friendly mycotoxin binders such as the MZNC that is synthesised and utilised in this research will help to produce secure food and feed products.

Rapid and Sensitive Detection of Aflatoxin B1, B2, G1 and G2 in Vegetable Oils Using Bare Fe3O4 as Magnetic Sorbents Coupled with High-Performance Liquid Chromatography with Fluorescence Detection

This paper reports a simple, sensitive and reliable method for the simultaneous detection of aflatoxin B1, B2, G1 and G2 in vegetable oils. Aflatoxins were extracted by magnetic solid phase extraction followed by high-performance liquid chromatography, then postcolumn photochemical derivatization and finally detected by fluorescence detector. Vegetable oil samples were first diluted with hexane and then commercial bare Fe3O4 nanoparticles were directly employed as sorbents to extract aflatoxins from complex vegetable oil samples, which significantly simplified the procedure of sample preparation and largely improved the sample analysis throughput. The effects of various parameters such as the amount of sorbent, loading, washing and eluting conditions were carefully optimized to improve the extraction efficiencies of aflatoxins. Under the optimal conditions, the limits of detection of four aflatoxins ranged from 0.01 μg/kg to 0.16 μg/kg, and squared regression coefficients (R2) >0.9990 were obtained within the linear range of 0.1-20 μg/kg (except for aflatoxin G2 with 0.5-20 μg/kg). Furthermore, the recoveries spiked at four concentration levels in a blank vegetable oil sample were from 82.6 to 106.2%, with inter- and intraday relative standard deviations <9.8%, indicating good accuracy and precision of the proposed method.

A facile one-pot green synthesis of β-cyclodextrin decorated porous graphene nanohybrid as a highly efficient adsorbent for extracting aflatoxins from maize and animal feeds

In this paper, β-cyclodextrin (β-CD) supported on porous graphene nanohybrid (β-CDPG) was obtained by self-assembly of functionalized graphene nanosheets into a three-dimensional network in the presence of ascorbic acid via an in situ graphene oxide reduction and β-CD functionalization process during a hydrothermal reaction. The prepared supramolecular nanohybrid was further packed into a reusable syringe filter holder and applied as an adsorbent for solid phase extraction of four aflatoxins (B1, B2, G1, G2). Under optimal conditions, the detection limits and linear dynamic ranges were achieved in the range of 0.0075-0.030 μg kg^-1 and 0.025-100 μg kg^-1, respectively and the relative standard deviations were less than 6.1%. Good recoveries were observed for analyzing target AFs in maize and cereal-based chicken feed samples ranged from 90.5 to 105%. The method offered simultaneous advantages of high supramolecular recognition and enrichment capability of β-CD and the high specific surface area of the porous graphene.