Aflatoxins In Rice Research Articles

Determination of aflatoxins in rice from Penang, Malaysia by dispersive liquid–liquid micro-extraction and LC–MS/MS

Rice is one of the crops cultivated in Malaysia, and it is the main diet for most of the population. In this study, dispersive liquid–liquid micro-extraction (DLLME) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) were used to develop, optimise and validate a reliable, easy-to-use and quick approach to detect aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). The extraction recoveries in DLLME were enhanced by the addition of 5% salt, utilising chloroform as the extraction solvent and acetonitrile as the dispersive solvent. The DLLME parameters – the extraction solvent volume, salt concentration and dispersive solvent volume were optimised with Box–Behnken design (BBD) and response surface methodology (RSM). Under optimised experimental conditions, excellent linearity was obtained with a limit of detection (LOD) ranging from 0.125 to 0.25 ng g−1, a limit of quantitation (LOQ) ranging from 0.25 to 0.3 ng g−1 and a correlation value (R 2) of 0.990. The matrix effects were between −11.1% and 19.9%, and recoveries ranged from 87.4% to 117.3%. The optimised and validated method was used effectively to assess aflatoxins contamination in 20 commercial rice samples collected from local supermarkets in Penang, Malaysia. AFB1 was detected at 0.41–0.43 ng g−1 in two rice samples, below the regulatory limit.

Aflatoxin detoxification by thermal cooking treatment and evaluation of in vitro bioaccessibility from white and brown rice

Aflatoxins pose a severe risk to the human health. In this study, the detoxifying capacity of a thermal cooking treatment applied to white and brown rice spiked with aflatoxins B1, B2, G1 and G2 as well as the aflatoxin bioaccessibility in cooked rice after applying an in vitro digestion model was evaluated. The cooking treatment (boiling with water at 100 °C for 12 min) evidenced an important extraction capacity of the boiling water over aflatoxins (25 %-56 %), that was higher for brown rice. Moreover, aflatoxins G1 and G2 were unstable with losses around 35 %. The highest bioaccessibility percentage was obtained for white rice (60 %-83 %) compared to brown rice (28 %-47 %), due to aflatoxin losses from brown rice after the gastric step. These results confirm the potential of this thermal cooking treatment to reduce aflatoxins in rice and suggest the influence of the nutritional composition of each rice on aflatoxin behaviour.

Aflatoxins degradation and quality evaluation in naturally contaminated rice by dielectric barrier discharge cold plasma

In this study, dielectric barrier discharge (DBD) cold plasma was explored for degrading aflatoxins in naturally contaminated rice. Rice samples were inoculated with strains of toxigenic Aspergillus and incubated to produce various levels of aflatoxins. Cold plasma showed degradation rates of aflatoxin B1 (AFB1) and total aflatoxins (AFs) that were related to moisture content, oxygen content, treatment time and voltage. Generally, the treatment reduced 1.08%–55.34% of AFB1 and 4.23%–56.37% of AFs in rice under different conditions. Relative lower degradation rates can be due to low permeability of the plasma and interference from food matrix. In addition, no significant difference (P > 0.05) was found in moisture, protein, amylose and color of rice before and after treatment. However, cold plasma aggravated the fat oxidation of rice, and made its surface smoother and more porous. The results provided a theoretical basis for aflatoxins degradation from grain system using cold plasma. Industry relevanceIn this study, dielectric barrier discharge (DBD) cold plasma was applied in the degradation of aflatoxins in naturally contaminated rice, having obvious degradation effect and little quality impact. Cold plasma treatment, as a novel non-thermal processing technology, can reduce mycotoxins in food in order to fully ensure the product safety in various links, including production, storage and so on. Compared with other detoxification methods currently used in the industry, this technology can achieve similar or higher degradation effect in a shorter time. In addition, it is low-cost and will not pollute the environment or damage the sensory properties and nutritional value of products.

Aflatoxin in rice: a publication review

Contamination of food products by various types of fungi can pose a severe health threat to humans and livestock. Aflatoxin (AFS) is a toxic and carcinogenic metabolite of the Aspergillus fungus that can occur in rice. Many studies have been conducted on the content of aflatoxins in staple foods, including rice. A literature analysis was performed to get an overview of the development of aflatoxin publication in rice using the Scopus database (Elsevier) between 2010 - 2021. In this article, we describe the focus of trends and characteristics of publications and visualize the growing network. The analysis includes descriptive analysis, keyword network, author collaboration network, and country/regional cooperation analysis. Research on the content of aflatoxins in rice has increased sharply in the last 20 years. The cause of aflatoxins is that fungi can potentially infect food crops, posing a significant health risk to humans and livestock. Aflatoxins are also thought to inhibit growth (growth retardation), resulting in stunting or failure to thrive. The main areas of study for aflatoxins can be separated into four categories: (a) types of aflatoxins; (b) origin and development process of aflatoxins; (c) test methods; and (d) type of product.

Preparation of magnetic hyper-crosslinked polymer for high efficient preconcentration of four aflatoxins in rice and sorghum samples

Aflatoxins have carcinogenic effect on human health, developing effective adsorbents for their enrichment and detection is particularly required. A magnetic hyper-crosslinked polymer (MHCP-TPE) was prepared and used as a magnetic sorbent to adsorb and isolate aflatoxins from rice and sorghum samples prior to high performance liquid chromatography-fluorescence detection. MHCP-TPE exhibited good magnetic separation ability and reusability, with fast adsorption kinetics and quite good adsorption efficiency for the aflatoxins. At optimized conditions, a sensitive and reliable method was established for the determination of four aflatoxins (B1, B2, G1 and G2) in rice and sorghum samples. The limits of detection were 0.003–0.075 ng g−1 and 0.01–0.25 ng g−1 for rice and sorghum, respectively. Good method recoveries ranging from 83.0 % to 117 % were obtained, with relative standard deviations less than 8.0 %. This method offered a superior alternative to determine trace level of aflatoxins in cereal foods. MHCP-TPE holds great potential in separation science.

English

Mycotoxins constitute a real problem of public health because of their highly toxic effects for the populations. This study aims to evaluate the practices that favor aflatoxins and ochratoxin A development in rice sold on the markets of Abidjan (Cote d’Ivoire). A food consumption survey was conducted among 45 traders and 135 consumers of rice in three markets in Abobo and Cocody communes. A simple, open-ended questionnaire was submitted to the rice traders and consumers. It covered socio-demographic characteristics (age, sex, level of education), location and conditions of storage, place of supply, and knowledge of mycotoxins. Following the survey, 20 samples of rice, prized by the population, were collected and analyzed. Total aflatoxin and ochratoxin A levels were determined using HPLC coupled with mass spectrometry. The results revealed that all traders were unaware of the existence of mycotoxins. The storage and marketing of rice are housed in very unhygienic premises (lack of brick walls in some cases, poor quality tin roof, premises not swept regularly). Most traders renew their rice stocks over an average of one to two months (66.66% in Abobo; 79.99% in Cocody) and prefer to buy their supplies from large stores and other markets in Abidjan. Aflatoxin B1 (0.75±0.05 µg/kg) and total aflatoxin (1.73±0.34 µg/kg) were detected in the rice samples from Abobo market. The presence of Aflatoxins in rice could be related to poor post-harvest practices identified.  Key words: Rice, total aflatoxins, ochratoxin A, practices, Abidjan.

Study of photodegradation kinetics of aflatoxins in cereals using trilinear component modeling of excitation-emission matrix fluorescence data.

In this work, a smart analytical strategy that combines excitation-emission matrix (EEM) fluorescence detection with alternating trilinear decomposition (ATLD) algorithm was developed for fast, on-line and interference-free study on the photodegradation kinetics of aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1) in rice and wheat under UV-Vis light (λ = 250-500 nm) treatment. With the aid of prominent "second-order advantage" of ATLD method, pure fluorescence signals of two targeted analytes can be directly resolved out from heavily overlapping spectral environment and accurately quantified even in the presence of unknown matrix interferences. Cereal samples in kinetic processing of photodegradation were detected without complex pretreatment steps except for a simple extraction using methanol/water solution (4:1, v/v), which solves the problem facing varied matrix interferences in the case of on-line monitoring of aflatoxins. The kinetic signals of analytes of interest were directly extracted regardless of varied matrix backgrounds of various cereals. The kinetic curves and degradation speeds of AFB1 and AFG1 can be estimated by resolved quantitative data, optimal radiation conditions including 365 nm wavelength and 35 J m-2 density were discussed for high-efficiency detoxification control of aflatoxins in rice and wheat. This strategy was promising to be as an alternative tool for eco-friendly photodegradation kinetic study of mycotoxins or other hazards in complex foodstuff matrixes.

Aflatoxins in rice: Worldwide occurrence and public health perspectives.

Aflatoxins are fungal secondary metabolites that contaminate dietary staples worldwide, including maize, rice and groundnuts. Dietary exposure to aflatoxins is a public health concern due to their carcinogenic, acute and chronic effects. Rice is an important staple food consumed widely and consists of a major part of the diets for half of the world population. Human exposure to these mycotoxins is a serious problem especially in developing countries where hot and humid climates favor the fungal growth and where food storage conditions are poor and lack of regulatory limits enforcement. The recent developments of biomarkers have provided opportunities in assessing aflatoxins exposure and related health effects in the high-risk population groups. This review describes the worldwide occurrence of aflatoxins in rice during the period from 1990 to 2015 and biomarkers-based evidence for human exposure to aflatoxins and their adverse health effects. Aflatoxin is a potent hepatocarcinogen and humans may expose to it at any stage of life. Epidemiological studies reported an association between aflatoxin intake and the incidence of hepatocellular carcinoma in some sub-Saharan and Asian countries. Even daily high intake of rice with a low level of contamination is of health concern. Thus, it is necessary to implement effective strategies to prevent contamination and fungal growth in rice. A good agricultural and manufacturing practice should be applied during handling, storage and distribution of rice to ensure that aflatoxins contamination level is lower in the final product. Moreover, a regular survey for aflatoxins occurrence in rice and biomarkers-based studies is recommended to prevent and reduce the adverse health effects in the world population.

Occurrence of aflatoxins in rice and in cassava (Manihot esculenta) products (meal, bread) produced in Guyana.

A survey was conducted on Guyana's main staple foods, rice, cassava meal and cassava bread to determine the presence and concentration of aflatoxins (AFs) using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC) with fluorescence detection for concurrence. Aflatoxins are secondary metabolites of the fungus Aspergillus and can be a health risk to humans and animals.Results were compared with European Union Commission (EUC) maximum levels of total aflatoxins of 10μg/kg. Various types of rice (paddy, steamed paddy, cargo rice, white rice and parboiled rice) were randomly collected either directly from the field and rice mills in Guyana during the November 2015/March 2016 season. Of the total 186 composite samples of rice fractions collected from field and mills, 10% (19) had AF concentrations greater than the maximum EUC level of 10μg/kg. Fifteen samples had aflatoxin concentrations ranging from 10 to 171μg/kg, mean 54.4μg/kg; four samples were outliers. Since Guyanese consume mainly white and parboiled rice, composite samples were taken along the marketing chain at points of sale to determine the presence of AFs. Of the sixty samples of white rice collected, 6.7% (4) had AF concentrations greater than the EUC regulatory limits ranging from 31.9 to 131μg/kg, mean 80.8μg/kg. For the 57 samples of parboiled rice, 3.5% (2) samples exceeded the limit with values of 72.6 and 407μg/kg. Forty (40) samples each of cassava meal and cassava bread were analysed fresh and after 2months of storage, and no sample exceeded the ELISA detection limit of 0.5μg/kg.

Assessment of health risks from aflatoxins in rice commercialised in Riyadh, Kingdom of Saudi Arabia

This study aimed to assess the occurrence and health risk of aflatoxins (AF) in rice imported to Riyadh, Kingdom of Saudi Arabia (KSA). Rice samples (n=41) including long grain white rice (LGW), sh...

Simple determination of aflatoxins in rice by ultra-high performance liquid chromatography coupled to chemical post-column derivatization and fluorescence detection

A fast and simple analytical method was developed and characterized for the determination of aflatoxins (B1, B2, G1 and G2) in rice. The procedure is based on a simple solid-liquid extraction without further clean-up, and analysis by ultra-high performance liquid chromatography coupled with fluorescence detection. Fluorescence emission of aflatoxins B1 and G1 was enhanced by post-column chemical derivatization using pyridinium bromide perbromide. The analytical method was satisfactorily characterized in white and brown rice. Under optimum conditions, external calibration in solvent could be used for quantification purposes and limits of quantification were below the maximum contents established by the European Union regulation for these contaminants/commodity group combination (0.07–0.14 µg/kg for white rice and 0.20–0.28 µg/kg for brown rice). Recovery studies carried out at three different concentration levels (0.5, 2 and 5 µg/kg) showed values in the range of 84.5–105.3%, and RSDs ≤ 5%.

An On-Site, Ultra-Sensitive, Quantitative Sensing Method for the Determination of Total Aflatoxin in Peanut and Rice Based on Quantum Dot Nanobeads Strip.

An on-site, ultra-sensitive, and quantitative sensing method was developed based on quantum dot nanobeads (QDNBs) and a test strip for the determination of total aflatoxins (AFTs) in rice and peanuts. The monoclonal antibody against AFT (mAbAFT) was homemade and labeled with QDNB. After the pre-coating of the AFT antigen on the test line (T line), the competitive immunoreactions were conducted between AFT and AFT antigen on the T line with QDNBs-mAbAFT. Under optimal conditions, this approach allowed a rapid response towards AFT with a considerable sensitivity of 1.4 pg/mL and 2.9 pg/mL in rice and peanut matrices, respectively. The put-in and put-out durations were within 10 min. The recoveries for AFT in rice and peanut sample matrices were recorded from 86.25% to 118.0%, with relative deviations (RSD) below 12%. The assay was further validated via the comparison between this QDNB strip and the conventional HPLC method using spiked samples. Thus, the design provided a potential alternative for on-site, ultra-sensitive, and quantitative sensing of AFT that could also be expanded to other chemical contaminants for food safety.

Aflatoxins in Rice Artificially Contaminated with Aflatoxin-producing Aspergillus flavus under Natural Storage in Japan.

Aflatoxin (AFT) contamination is frequent in foods grown in tropical regions, including rice. Although AFTs are generally not found in temperate-region foods, global warming has affected typical temperate-region climates, potentially permitting the contamination of foods with AFT-producing Aspergillus flavus (A. flavus). Here we investigated the AFT production in rice during storage under natural climate conditions in Japan. We examined AFTs in brown rice and rough rice artificially contaminated with A. flavus for 1 year in Japan, and we subjected AFTs in white rice to the same treatment in airtight containers and examined the samples in warm and cold seasons, simulating the storage of white rice in general households. In the brown rice, AFTs increased after 2 months (March) and peaked after 9 months (October). The AFT contamination in the rough rice was minimal. After the polishing and cooking of the brown rice, AFTs were undetectable. In the white rice stored in airtight containers, AFTs increased after 1 month (August) and peaked after 2 months (September). Minimal AFTs were detected in the cold season. Thus, AFT contamination in rice may occur in temperate regions following A. flavus contamination. The storage of rice as rough rice could provide be useful for avoiding AFT contamination.

Antibody-Free Colorimetric Detection of Total Aflatoxins in Rice Based on a Simple Two-Step Chromogenic Reaction.

The prevalently used immunoassays for fast screening of aftatoxins (AFs) usually cannot meet the requirement for simultaneous determination of total AFs (aflatoxin B1 + aflatoxin B2 + aflatoxin G1 + aflatoxin G2) due to the deficiency of highly group-specific antibodies. This paper describes a two-step chromogenic reaction based method to quantitatively detect total AFs in rice using colorimetric measurement without antibody. In the method, colorless AFs transform into green-colored indophenol products through the reaction with sodium hydroxide and 2,6-dibromoquinone-4-chloroimide (DBQC) successively, allowing selectively determining total AFs up to 3.9 μg/kg over other competitive mycotoxins under optimal conditions by a UV-vis spectrophotometer. In addition, the colorimetric measurement results of the rice samples agree well with that of a standard HPLC method, demonstrating the good reliability and applicability of the method. Uniquely, the method has potential for on-site detection of total AFs in rice when using a nylon membrane-based device.

Post-harvest operations and aflatoxin levels in rice (Oryza sativa)

This study evaluated the effect of post-harvest operations on the occurrence of aflatoxins in rice (Oryza sativa) samples. Newly harvested rice was subjected to stationary, intermittent, or combined drying, and stored in concrete storehouses during 10 months. The aflatoxins were extracted with methanol: potassium chloride and quantified by HPLC-FL. After ten months of storage, the highest aflatoxin levels were found in rice bran, of which the values were above 25 μg/kg for the sum of the aflatoxins (B1 + B2 + G1 + G2). The rice fractions of the endosperm and husk from the intermittent drying showed the lowest aflatoxin levels during the storage.

Mycotoxin monitoring for commercial foodstuffs in Taiwan

Mycotoxins are toxic food contaminants that are naturally produced by certain fungi. They induce negative effects on human health by making food unsafe for consumption. In this study, analyses were performed to determine the levels and incidence of aflatoxins (AFs) in peanut products, tree nuts, spices, and Coix seeds; ochratoxin A (OTA) in wheat and roasted coffee, as well as OTA and AFs in rice; and citrinin (CIT) in red yeast rice (RYR) products. A total of 712 samples from nine different food categories were collected between 2012 and 2013. The samples were analyzed over 2 years for AFs, OTA, and CIT by methods recommended by the Ministry of Health and Welfare. These official analytical methods were extensively validated in-house and through interlaboratory trials. The analytical values of suspected contaminated specimens were confirmed by liquid chromatography – tandem mass spectrometry analysis to identify the specific mycotoxin present in the sample. We show that 689 samples (96.8%) complied with the regulations set by the Ministry of Health and Welfare. AFs were found in four peanut-candy products, one peanut-flour product, one pistachio product, one Sichuan-pepper product, and one Coix seed product. All had exceeded the maximum levels of 15 parts per billion for peanut and 10 parts per billion for other food products. Furthermore, 14 RYR samples contained CIT above 5 parts per million, and one RYR tablet exceeded the maximum amount allowed. Instances of AFs in substandard Sichuan pepper and Coix seeds were first detected in Taiwan. Measures were taken by the relevant authorities to remove substandard products from the market in order to decrease consumer exposure to mycotoxin. Border control measures were applied to importing food commodities with a higher risk of mycotoxin contamination, such as peanut, Sichuan pepper, and RYR products. Declining trends were observed in the noncompliance rate of AFs in peanut products, as well as that of CIT in RYR raw materials monitored from 2010 to 2013.

Extraction of aflatoxins from food samples using graphene-based magnetic nanosorbents followed by high-performance liquid chromatography: a simple solution to overcome the problems of immunoaffinity columns.

In this research, magnetic graphene nanoparticles were prepared and used as adsorbents for preconcentrating the aflatoxins in rice, wheat, and sesame samples. For this purpose, graphene was synthesized by Hummer's method. Magnetically modified graphene formed by the deposition of magnetite (Fe3O4) on graphene was used for the separation of aflatoxins B1, B2, G1, and G2 from the samples. The extractants were subsequently analyzed with high-performance liquid chromatography and fluorescence detection. Parameters affecting the efficiency of the method were thoroughly investigated. The measurements were done under the optimized conditions. For aflatoxins B1, B2, G1, and G2, limits of detection were 0.025, 0.05, 0.05, and 0.075 ng/g and limits of quantification were 0.083, 0.16, 0.16, and 0.23 ng/g, respectively. Accuracy was examined by the determination of the relative recovery of the aflatoxins. The relative recovery of aflatoxins B1, B2, G1, and G2 were quite satisfactory (between 64.38 and 122.21% for food samples). Relative standard deviations for within laboratory repeatability (n = 6) were in the range from 1.3 to 3.2. The application of this sorbent for the separation and concentration of the mentioned aflatoxins from food samples was examined.

Determination of Aflatoxins in Rice and Maize by Ultra-High Performance Liquid Chromatography–Tandem Mass Spectrometry with Accelerated Solvent Extraction and Solid-Phase Extraction

A fast and reliable ultra-high performance liquid chromatography–tandem mass spectrometry method was developed for the determination of aflatoxins B1, B2, G1, and G2 in cereal. The analytes were extracted by accelerated solvent extraction with methanol/water (80:20). A polymeric solid-phase extraction column was used for sample preparation. Under optimum conditions, the analyte recoveries for samples spiked at different concentration levels in rice and maize ranged from 71.2 to 94.0%, with relative standard deviations less than 16.4%. Limits of detection (signal-to-noise ratio, 3:1) for the aflatoxins ranged from 0.25 to 0.93 ng/g. The developed method was applied to the determination of aflatoxins in ten rice and maize samples. One maize sample tested positive with an aflatoxin B1 concentration of 2.7 ng/g.

Aflatoxin contamination in different fractions of rice from Pakistan and estimation of dietary intakes

The purpose of this study was to determine the distribution of aflatoxins in rice milling fractions and to estimate dietary intakes. A total of 413 rice samples (paddy 58, parboiled 69, brown 84, white 93, and broken 109) were analyzed by HPLC with fluorescence detector. The results showed that 64% paddy (16.35 ± 1.67μg/kg), 38% parboiled (14.20 ± 2.04μg/kg), 33% brown (9.85 ± 1.25μg/kg), 42% white (7.10 ± 1.39μg/kg), and 50% broken (8.5 ± 1.71μg/kg) rice samples were contaminated with aflatoxins. It was found that paddy rice was most contaminated with aflatoxins while white rice was least contaminated. The percentage of samples exceeding EU maximum contents for total aflatoxins in rice (4μg/kg) varied from 14 to 36% when compared to the analyzed rice fractions. The total estimated amount of aflatoxin intake for average rice consumers ranged from 19.1 to 26.6ng/kg body weight/day, much higher than the reference value of 1ng/kg body weight/day. This is the first report discovering that rice is a major contributor to the dietary intake of aflatoxins in Pakistan.

Survey on the occurrence of aflatoxins in rice from different provinces of Iran

Aflatoxins were surveyed in 256 rice samples taken from retail markets in different provinces of Iran during October 2007 and July 2008. A methanol/water (80 : 20, v/v) mixture and an aflatoxin immunoaffinity column (IAC) were used for extraction and clean-up. Mycotoxins were determined using HPLC with fluorescence detection and post-column derivatization using a photo-ionization cell. Levels of contamination ranged 0.0–5.8 ng g−1 (mean, 1.4 ng g−1) and 0.1–6.3 ng g−1 (mean, 1.6 ng g−1) for AFB1 and total aflatoxins, respectively. AFB1 was detected in almost all samples. Results showed that 55 samples (21.5%) were contaminated with more than 2 µg kg−1 of AFB1, while seven samples (2.7 %) contained more than 4 µg kg−1 total aflatoxins. The calculated probable daily intake of AFB1 from rice for Iranians ranged 1.4–5.8 ng AFB1 per kg body weight per day for average consumers and, hence. exceeding the estimated provisional maximum tolerable daily intake.