Aflatoxin M1 Concentration Research Articles

Development of carbon quantum dot-based lateral flow immunoassay for sensitive detection of aflatoxin M1 in milk

Currently, there is a great demand for simple, sensitive, and accurate sensors for aflatoxin M1 (AFM1) in dairy products. In the present research, a novel fluorescent immunosensor based on nitrogen-doped carbon quantum dots (CQDs) has been developed for AFM1 analysis. The N-doped CQDs were synthesized through the hydrothermal approach using citric acid and polyethyleneimine as precursors. The CQDs showed bright blue emission under ultraviolet light irradiation and a maximum emission was observed at 450 nm upon excitation at 350 nm. The anti-AFM1 antibody (Ab) was immobilized on the as-obtained amine-functionalized CQDs and the obtained CQDs/Ab probe was then directly used for developing the immunoassays for AFM1. The fluorescence of the CQDs/Ab solution was effectively quenched in the presence of increasing AFM1 concentrations. Under the optimized conditions, the fluorescent nanosensor exhibited high sensitivity towards AFM1 in the range of 0.2–0.8 ng/mL with low limit of detection i.e., 0.07 ng/mL in standard buffer. Furthermore, the CQDs/Ab immunosensor was developed as a lateral flow design for detecting the aflatoxin residues in milk. This strategy can be used for the development of low-cost, rapid, and highly sensitive sensor strips for the detection of AFM1 in dairy products.

Decrease in Aflatoxin M1 Concentration in Milk during Cholesterol Removal by Application of β-Cyclodextrin.

Approximately one-third of humankind is chronically exposed to the carcinogenic aflatoxin M1 contained in milk. As β-cyclodextrin is frequently used in the food industry, its effect on aflatoxin M1 concentration was investigated during cholesterol removal from milk due to the similarity among the physicochemical properties of aflatoxin M1 and cholesterol. Moreover, the elimination of cholesterol using β-cyclodextrin has been successfully applied in many studies without any substantial effect on the quality of the treated milk. Therefore, milk samples were spiked with aflatoxin M1 within the range from 0.20 to 2.00 µg/kg, and cholesterol removal was carried out by 2.0% (w/w) β-cyclodextrin addition, as this concentration is enough for the sufficient removal of cholesterol. It was found that the mean cholesterol concentration decreased by 92.3%, while the aflatoxin M1 concentration decreased to 0.53 ± 0.04 µg/kg, i.e., by 39.1% after treatment (n = 2). This mitigation procedure itself is easy and inexpensive and thus is fully applicable with a high potential for complete decontamination of aflatoxin M1 milk. This method will therefore considerably improve the food safety issues associated with aflatoxin M1 presence in milk and dairy products.

Aflatoxin M1 in Raw Milk, Pasteurized Milk and Cottage Cheese Collected along Value Chain Actors from Three Regions of Ethiopia.

Milk is a highly nutritious and perfect natural food for humans. However, when lactating animals feed on Aflatoxin B1 (AFB1)-containing feed, the hydroxyl metabolite aflatoxin M1 (AFM1) contaminates the milk and dairy products. The objective of the current study was to assess the level of AFM1 in raw milk, normally pasteurized milk and Ethiopian cottage cheese collected from value chain actors (producers, collectors, processors and retailers). Cross-sectional study and simple random techniques were used to collect primary samples. A total of 160 composite samples was collected; raw milk (n = 64), pasteurized milk (n = 64) and cheese (n = 32) was analyzed. Quantitative analysis of AFM1 was conducted using enzyme-linked immunosorbent assay (ELISA). The results indicate that AFM1 was detected in all milk products. Results along value chains show that the concentration of AFM1 in raw milk from collectors was significantly higher than from producers, and in pasteurized milk from processors and retailers (p < 0.05). However, no significant (p > 0.05) difference was observed in cottage cheese value-chain actors in all regions. Comparison of AFM1 mean values among all dairy products shows that raw milk had a significantly higher concentration of AFM1 followed by pasteurized milk and cottage cheese. However, there was no significant difference between raw and pasteurized milk (p > 0.05). The mean AFM1 contamination in milk products ranged from 0.137 to 0.319 µg/L (mean value 0.285 µg/L). The contamination percentages of AFM1 in raw milk (62.50%), pasteurized milk (67.20%) and cottage cheese (25%) were above the regulatory limit set by the European Union (EU) (0.05 µg/L). According to USA/Ethiopian Standard (US/ES) (0.50 µg/L), 21.87%, 25% and 1% exceeded the regulatory limit for the above products, respectively. The overall prevalence (56.88%) was above the EU regulatory limit and 19.38% over US/ES regulations. Therefore, to provide accurate information about the health risk to consumers, there is a need to conduct risk assessment studies in consumers of milk and dairy products at different age groups.

Human health risk assessment of aflatoxin M1 in raw and pasteurized milk from the Kermanshah province, Iran

The principal purpose of this study was to investigate the amount and human health risk assessment by Monte Carlo simulation for aflatoxin M1 (AFM1) in milk in Kermanshah province, Iran. For this purpose, a total of 108 composite samples were analyzed for AFM1 levels using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Based on AFM1 in milk, aflatoxin B1 (AFB1) in animal feed, exposure, and human health risk were evaluated. The results showed that the total mean of AFM1 in raw milk in summer and winter was 49 ± 2 and 14 ± 1 ng/L, respectively, while in pasteurized milk was 6 ± 1 and 10 ± 1 ng/L, respectively, and in general, the mean amount of AFM1 in both raw and pasteurized milk is significantly different between summer and winter. Based on the results, it was found that 16.7% of all samples had AFM1 higher than the European Union (EU) limit (50 ng/L). Accordingly, the AFM1 level of raw milk in summer had health risks for all age groups of men and women. In conclusion, in Kermanshah province, AFM1 concentrations in milk produced by livestock should be reduced, especially during the summer seasons; basic procedures should be implemented to reduce AFB1 concentrations in lactating animals' foods.

Preliminary sampling of aflatoxin M1 contamination in raw milk from dairy farms using feed ingredients from Rwanda.

Milk is susceptible to aflatoxin M1 (AFM1) contamination when dairy cattle consume feed contaminated with aflatoxins and is considered as a public health concern. This pilot study assessed the prevalence and amount of total aflatoxin contamination in commercially available dairy feed and the corresponding AFM1 contamination in raw milk from samples collected at farms using local, commercially available dairy feed across Rwanda's five provinces. The inclusion criteria to select dairy farm participants were (1) to have at least two cows and (2) use of commercially prepared dairy feeds. Importantly, the majority of cattle rearing households in Rwanda rely principally on grazing or other freely available feedstock, rather than on commercially prepared feeds. In total, 170 raw milk samples were collected during one sampling period from dairy farms using commercially prepared dairy feeds. In addition, 154 dairy feed samples were collected simultaneously with the milk samples. These farms were previously targeted in a larger study measuring aflatoxin contamination of Rwandan feeds and feed ingredients. The mean AFM1 concentration in these samples was 0.89 ± 1.64µg/l (median: 0.33µg/l) with a maximum of 14.5µg/l. Maize bran was the principal dairy feed ingredient used by farmers in the sampling, representing more than 65% of the total feed samples collected, with mean aflatoxin concentration of 90.5µg/kg (median 32.3µg/kg). The authors note that this preliminary sampling is not generalizable across Rwandan milk production and consumption; the limited pilot study presented here was not designed with the robustness necessary for broad-scale generalization. Thus, the data presented should not be broadly applied outside of the context of the study.

Levels of Aflatoxin M1 in Breast Milk of Lactating Mothers in Monterrey, Mexico: Exposure and Health Risk Assessment of Newborns.

The present study aimed to determine the presence of the aflatoxin M1 (AFM1) in breast milk samples from 123 nursing women and the degree of exposure of infants to this toxin, in the metropolitan area of Monterrey, Nuevo Leon state (northeast Mexico). Upon analysis, 100% of the samples were found to be contaminated with the toxin at an average concentration of 17.04 ng/L, with a range of 5.00 to 66.23 ng/L. A total of 13.01% of the breast milk samples exceeded the regulatory limit of 25 ng/L for AFM1 concentration, set by the European Union. The estimated daily intake for AFM1 and the carcinogenic risk index were also determined in the 0- to 6-, 7- to 12-, 13- to 24-, and 25- to 36-month-old age groups. The AFM1 intake through breast milk ranged from 1.09 to 20.17 ng/kg weight/day, and was higher than the tolerable daily intake, indicating a carcinogenic risk for infants in the age groups of 0- to 24-months old. This evidence demonstrates a susceptibility of breast milk to AFM1 contamination that may suggest a carcinogenic risk for the breastfed infants in Monterrey city, Nuevo Leon state, and the need to control the presence of aflatoxins in foods eaten by nursing mothers.

Occurrence of aflatoxin M1 in yogurt and milk in central-eastern China and the risk of exposure in milk consumers

We investigated the occurrence of aflatoxin M1 (AFM1) in yogurt and milk, including pasteurized, ultra-high temperature (UHT), and extended shelf life (ESL) milk samples, from central-eastern China and assessed the risk of AFM1 exposure in consumers. We collected 845 milk samples, consisting of yogurt (329), pasteurized milk (288), ESL milk (120), and UHT milk (108) from Hubei, Zhejiang, and Fujian provinces during winter season. The AFM1 levels in milk samples were determined using a validated enzyme-linked immunosorbent assay method. We detected AFM1 in 194 yogurt samples (59.0%) and 427 milk samples (82.8%). Four yogurt samples (1.2%) and 14 milk samples (2.7%) exceeded the European Union legal limit (50 ng/L) but were below the Chinese legal limit (500 ng/L). AFM1 concentration was lower in UHT milk than that in ESL and pasteurized milk (p < 0.05). Infants between 2 and 3 years of age had the highest risk of AFM1 exposure, with the estimated daily intake of 0.25 and 0.23 ng/kg bw/day for male and female groups, respectively. Therefore, AFM1 contamination in milk products should be monitored and reduced to lower levels, given the high prevalence and the risk of AFM1 exposure in infants.

Association between aflatoxin M1 excretion in milk and indicators of rumen fermentation in bovines.

Aflatoxins and its metabolites negatively impact the ruminant health and production. The present cross-sectional study was aimed to determine the effect of aflatoxins on rumen fermentation by deducing the correlation between the aflatoxin M1 (AFM1) excretion in milk and indicators of rumen fermentation in bovines. The indicators of rumen fermentation were taken into account and correlated with AFM1 concentration in milk of 120 bovines (cattle (n = 82) and buffalo (n = 38)). The AFM1 in milk samples (n = 120) was quantified by ELISA kit. The correlation analysis revealed that with increase in excretion of AFM1 in milk, the pH (r = 0.38), methylene blue reduction time (MBRT) (r = 0.43), sedimentation activity time (SAT) (r = 0.31) and ammonia nitrogen content (r = 0.34) of rumen liquor increase, whereas the total volatile fatty acid (TVFA) content (r = - 0.25), total bacterial count (TBC) (r = - 0.43) and total protozoal count (TPC) (r = - 0.14) of rumen liquor decrease. The results of the present study suggest that the presence of aflatoxins in rumen could have negative effect on the process of rumen fermentation. Therefore, the prevention of primary entry point(s) of AFB1 through the feed of bovines is important for the animal health as well as public health.

One-step automatic sample pretreatment for rapid, simple, sensitive, and efficient determination of aflatoxin M1 in milk by immunomagnetic beads coupled to liquid chromatography-tandem mass spectrometry

Milk, the most consumed dairy product, is often contaminated by the carcinogenic aflatoxin M1. Here, we present a one-step automatic sample pretreatment method using immunomagnetic beads and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for the detection of aflatoxin M1 in milk with good linearity and sensitivity (detection limit = 0.0008 μg/kg and quantitation limit = 0.0027 μg/kg). Forty-five randomly purchased brands of milk from Chinese supermarkets were analyzed using the newly developed method. The positive rate of samples was 86.7%, the average content was 0.0058 μg/kg, the qualified rate was 100%, and no samples exceeded the prescribed limit (<0.025 μg/kg). The recoveries of the four different aflatoxin M1 concentrations (0.05, 0.10, 0.25, and 0.50 μg/kg) in milk samples under the optimized conditions were 86.2–102.9% with relative standard deviations (RSD) < 4.0%. The one-step automatic sample pretreatment method effectively simplifies the operation and reduces human error. Additionally, the mycotoxin automatic clean-up system used in this method can process up to 24 samples at the same time, reducing the clean-up time to ∼30 s/sample. Thus, the LC-MS/MS method offers high speed, sensitivity, and accuracy of the aflatoxin M1 quantification in milk, while being cheaper, operationally easier, and less prone to human errors than conventionally used procedures.

Fate of aflatoxins M1 and B1 within the period of production and storage of Tarkhineh: A traditional Persian fermented food.

The objective of the study was to assess the amount of aflatoxin M1 (AFM1) and aflatoxin B1 (AFB1) during fermentation, drying, and storage of Tarkhineh—a traditional Persian fermented food—over four months. Tarkhineh samples were produced based on a traditional method. Various concentrations of AFB1 (2.5, 5, 7.5, and 10 µg/kg) and AFM1, stood at 0.25, 0.5, 0.75, and 1 µg/kg, were added to Iranian yogurt drink, called doogh, samples. Tarkhineh samples were evaluated for AFB1 and AFM1 on days 0, 2, 6, and 8 and also after drying and four months of storage. In cases of repeatability, recovery, and reproducibility, the high‐performance liquid chromatography through fluorescence detector (HPLC‐FD) method was successfully done to demonstrate aflatoxins (AFs) in Tarkhineh samples. The fermentation process had a considerable consequence on the reduction in AFM1 and AFB1 as compared to the control group, evidenced by 65.10%–81.20% and 55.80%–74.10%, respectively, after eight days of fermentation (p < .05). The highest reduction in AFB1 existed in samples containing 2.5 µg/kg toxin, followed by 5, 7.5, and 10 µg/kg, respectively. A similar trend was found for AFM1, as the highest concentration was found in samples containing 0.25 µg/kg toxin, followed by 0.5, 0.75, and 1 µg/kg, respectively.

Dietary Aflatoxin B1-related risk factors for the presence of Aflatoxin M1 in raw milk of cows from Ecuador

Background:Aflatoxin M1 (AFM1) is hepatotoxic and carcinogenic, and it may be present in milk due to dairy cow’s ingestion when feed is contaminated with Aflatoxin B1 (AFB1).Aim:The objective of this research was to determine the potential risk factors of dietary AFB1 contamination in dairy cows, which causes AFM1 contamination of the raw milk, through an epidemiological survey and statistical analysis.Methods:209 raw milk samples were collected, and AFM1 concentrations were detected by lateral flow immunochromatographic assay.Results:It was determined that 100% of the samples contained concerning levels of this mycotoxin with a mean of 0.077 μg/kg, which exceeds the maximum allowed by the European Union legislations (0.05 μg/kg) but not Ecuadorian Regulations (0.5 μg/kg). An adjustment to a linear model by weighted least squares was used to correct the presented heteroscedasticity. Potential risk factors for dietary AFB1 contamination were analyzed in relation to the appearance of AFM1 in milk from Ecuador. Among factors including legumes consumption, the use of silage, type of production system (intensive, extensive, and mixed), and farm size (small, medium, and big), the intensive production system and the big producers presented higher levels of AFM1.Conclusion:Considering that all the milk samples presented AFM1 and since there is no specific feed determined to be a risk factor, it was concluded that any of the feed offered to dairy cows may be contaminated with AFB1. It is necessary to reduce AFB1 levels in feed by implementing good agricultural practices and improving feed storage to decrease milk AFM1 levels. This study identified that intensive systems have a lot of animals, and silage is incorporated into the diet, which can significantly increase AFM1 levels.

The use of the two different mycotoxin deactivators in the nutrition of dairy cows

The aim of this study was to investigate the effect of two different commercial products for mycotoxin deactivation in the dairy cows’ nutrition. The research was done on the 18 dairy cows in the different phase of lactation, with the average production of 14 L of milk per day. The diet contained in average 8 kg of concentrate feed, 10 kg of mixed peas and wheat forage, 4 kg hay of alfalfa and cereal straw ad libitum. Before starting the trials all components of the cows’ ration were analysed for the presence of aflatoxin B1, while cow’s milk was analysed for the presence of aflatoxin M1. In the first phase of the trial cows were fed diet containing aflatoxin B1 at level of 5±0.9 µg/kg, which resulted in the average aflatoxin M1concentration of 181±3.5 ng/kg in the milk. In the second phase of the trail 0.5% of the commercial product 1 (Neozel®) was added into the feed ration of cows and after the period of adaptation, the aflatoxin M1 concentration in milk was measured. In the third phase of the trail 0.3% of the commercial product 2 (miko-Stop 0.3®) was added into the feed ration of cows and also, after the period of adaptation, the concentration of aflatoxin M1 in milk was measured. The last phase was the control phase in which cows were fed diets with aflatoxin B1 (5 µg/kg) without added mycotoxin deactivators. The use of both commercial products for ten days resulted in the reduction of aflatoxin M1 levels for 35.9% and 53.6%, respectively.

Presence of Aflatoxin M1 in Commercial Milk in Paraguay

The presence of aflatoxin M1 (AFM1) in milk is a public health concern because milk is a significant part of human diets worldwide. In economies where AFM1 monitoring is low or nonexistent, the possibility of AFM1 contamination might be increased. Our study was conducted to detect and quantify AFM1 in fluid milk and milk drinks of various brands, fat concentrations, packages, and heat treatments sold in the Metropolitan Area of Asunción, Paraguay. Eighty samples were collected from supermarkets in the Metropolitan Area of Asunción following a nonprobability sampling method. An enzyme-linked immunosorbent assay for AFM1 (25 to 500 ppt) was used to quantify the toxin, and results were analyzed with nonparametric methods. All samples were positive values for AFM1 (above the detection limit of 25 ng/kg); 85% of the samples had 30 to 50 ng/kg, and 15% had >500 ng/kg. No significant difference in AFM1 concentration was found based on fat concentration, heat treatment, or type of packaging of these milk products; however, significant differences were found between brands.

Innovative application of postbiotics, parabiotics and encapsulated Lactobacillus plantarum RM1 and Lactobacillus paracasei KC39 for detoxification of aflatoxin M1 in milk powder.

This study aimed to evaluate aflatoxin M1 (AFM1) level in milk powder and infant milk formulae, in addition to applying innovative methods for AFM1 & AFB1 detoxification. Fifty random samples of milk powder and infant formulae (25 of each) were collected from the Egyptian markets for assessing AFM1 level using ELISA technique. Bioactive components comprising cell free supernatants (postbiotic), acid-dead cells (parabiotic) and the encapsulated-cells of Lactobacillus plantarum RM1 and Lactobacillus paracasei KC39 were evaluated for their antifungal activity against toxigenic mold strains and their impact on AFB1 and AFM1 reduction in reconstituted milk powder. AFM1 concentration in unpacked milk powder was higher than that of packed samples and infant formulae, although these differences were not significant (P > 0.05). About 96.0, 29.4 and 25.0% of the tested infant formulae, unpacked, and packed milk powder were unacceptable in terms of the AFM1 limit defined by Egyptian and European standards, while all samples were in accordance with the USA/FDA standard. All tested mycotoxigenic strains were sensitive to the different treatments of the probiotics with the highest sensitivity regarding Fusarium strain with L. paracasei KC39 compared to other genera. The degradation ratios of AFM1 using the bioactives of the L. paracasei KC39 were higher than that of L. plantarum RM1 bioactives. Additionally, KC39 parabiotic manifested the best AFB1 reduction (60.56%). In conclusion, the positive and highly significant relationship (P < 0.05) between these effective biocompounds mirrors their major detoxification role which gives a safe solution for AFs contamination issues in milk and milk products.

Quantitative risk assessment for aflatoxin M1 associated with the consumption of milk and traditional dairy products in Argentina

A quantitative risk assessment for exposure to aflatoxin M1 (AFM1) related to the consumption of milk and traditional dairy products of Argentina was developed. The frequency and concentration of AFM1 was modelled at various stages through the milk processes, considering Argentinean practices. Concentration of AFM1 (0.046μg/l, 95%CI = 0.002-0.264μg/l) in raw milk was estimated. The AFM1 concentration in milk was sensitive to the carry-over rate (r = 0.80), and milk yield in the first third of lactation during the spring-summer season (r = 0.11). AFB1 levels in silage (r = 0.22), pasture during the spring-summer season (r = 0.11), concentrate (r = 0.08), and cotton seed (r = 0.05) were the factors most correlated with AFM1 concentrations. Although the results showed that MoE values for the mean and median exposure to AFM1 were < 10,000 in infants, toddlers, and other children, the additional cancer risk due to exposure to AFM1 in infants, toddlers, and other children was 0.007, 0.005, and 0.0009 additional cases per year per 100,000 individuals, respectively, which indicates no health concern. In addition, the percentages of the population exceeding HI values (HI > 1) for exposure to AFM1 for infants, toddlers, and other children were 45%, 49.1%, and 40.6%, respectively. Under this scenario, the most susceptible population at risk was children < 10years old; therefore, it is necessary to establish measures to prevent contamination of AFM1 in milk and milk products.

Occurrence and associated factors of aflatoxin M1 in raw cow milk in South Gondar Zone, North West Ethiopia, 2020.

Aflatoxin M1 is the most significant toxin of milk and milk products. It is immunosuppressive, mutagenic, and carcinogenic compounds to humans. Therefore, this study was aimed to evaluate the concentration of aflatoxin M1 and its determinants in raw cow milk sample intended for human consumption in South Gondar Zone, Ethiopia. A cross‐sectional study was conducted on a total of 100 dairy farmers from January to February 2020. Around 50 ml, 100 raw milk samples were collected for aflatoxin M1 analysis. A simple random sampling technique was applied to get the households. Binary and multivariate logistic regressions were used to see the association between predictor and outcome variables. From the 100 dairy farmers who had participated, 38% had heard about aflatoxin in the milk sample. Aflatoxin M1 was detected in the 99(99%) raw milk samples, of these 41 (41%) exceeded the limit of the European Union. The logistic regression analysis result showed that residence, awareness about the level of aflatoxin in the milk sample, management mold‐contaminated animal feed, animal feed storage facility, and grazing systems were significantly associated with the high level of aflatoxin in the milk sample. Almost all milk samples analyzed were positive for aflatoxin M1, and 41% of samples were above the limit set by European Union. Many easily manageable and preventable factors were associated with higher levels of aflatoxin M1 in the milk sample than the European Union limit, which suggests continuous monitoring of milk and milk products is necessary.

Occurrence and exposure assessment of Aflatoxin M1 in milk and milk products in India.

Milk containing Aflatoxin M1 (AFM1) poses a serious health risk to consumers. Present study was undertaken to determine levels of AFM1 in 146 milk and value added dairy products sold in retail markets of Chhattisgarh, India using HPLC coupled with fluorescence detector. A total of 52 samples (35.6%) were found to contain AFM1 with overall concentrations ranging from nd -2.608µg/L. The contamination levels were higher in non-fermented milk products than fermented milk products samples, although this difference was statistically non-significant (p > 0.05). AFM1 concentrations above maximum permissible limits established by the European Commission were found in 94.2% of positive samples. Health risk assessments ascertained that the estimated daily intakes for AFM1 is higher than the established tolerable daily intakes for both adults and children (Hazard Index > 1), there by implying a potentially high risk to consumer's health. Current investigation provides valuable information regarding contamination of raw as well as value added milk products sold in Indian markets. Therefore, to protect consumer's health and promote dairy trade; there is an urgent need to increase farmer's knowledge on good storage practices of feed and fodder. Further, stringent enforcement of food safety regulations is imperative to safeguard and promote human health.

The behavior of aflatoxin M1 during lactic cheese production and storage

This study aimed to determine the fate of aflatoxin M1 (AFM1) during lactic cheese processing and storage. About 70.72% of the total AFM1 content of the raw milk was carried over into the whey. The levels of AFM1 during cheese storage were reduced by 77.66%. The transfer of the AFM1 into the brine solution depended on the storage time and showed variable trends. Collectively, 6.42% of the total AFM1 content of milk remained in lactic cheese, and 93.58% of it was removed during production and storage. Lactic cheese could be safer than milk from the AFM1 level point of view.

A bivalent binding aptamer-cDNA on MoS2 nanosheets based fluorescent aptasensor for detection of aflatoxin M1

To ensure the safety of dairy products, especially milk, and consequently protect human health, accurate and simple analytical techniques are highly necessary to determine the low concentration of aflatoxin M1 (AFM1) as an important carcinogen. Herein, a novel, accurate and simple fluorescent aptasensor was designed for selective detection of AFM1 based on bivalent binding aptamer-cDNA (BBA-cDNA) structure. Moreover, MoS2 nanosheets (MoS2 NSs) were used as the fluorescent quencher and FAM-labeled complementary strand of aptamer (FAM-CS) was applied as a fluorescent probe. In this study, we achieved a new result. Unlike previous studies, in this work, the BBA-cDNA structure was not disassembled in the presence of the target. Therefore, as the AFM1 concentration increased, more targets were attached to the BBA-cDNA structure and as a result, the BBA-cDNA structure/AFM1 could not be placed on the surface of MoS2 NSs, leading to the more fluorescent intensity detection. Under optimized conditions, the developed fluorescent analytical method revealed great selectivity toward AFM1 with a limit of detection (LOD) of 0.5 nM and a linear range from 0.7 to 10 nM. This fabricated aptasensor indicated excellent analytical performance for AFM1 detection in milk samples with LOD of 0.1 nM. Overall, the proposed approach could provide an effective basis for small molecule analysis to guarantee food and human safety using appropriate aptamer sequences.

Aflatoxin B1 contamination of feedstuff on a dairy farm in Northern Peru and aflatoxin M1 concentrations in raw milk

Research regarding aflatoxin contamination levels in Peru is limited, although aflatoxin M1 (AFM1) and aflatoxin B1 (AFB1) require surveillance because of their toxicity. European regulations state that the harmonised maximum level (ML) is 5 μg/kg for AFB1 in feedstuffs and 0.05 μg/kg for AFM1 in milk. Our study aimed to determine the annual variation levels of AFB1 in ingredients used in feedstuffs for dairy cows and those of AFM1 in milk at a typical intensive dairy farm in Northern Peru. For 1 year, milk (n=529) and feedstuff samples (n=235) were collected and aflatoxin levels were determined using a lateral flow immunoassay. We found that 16% of milk samples had AFM1 contamination above the ML. AFM1 level was significantly higher (P&lt;0.05) in December (end of spring) than that in all other months. Throughout the year, the most used feedstuffs were maize, soybean meal and whole soybean. Among the maize samples (n=77), 2.59% had an AFB1 level above the ML, whereas 45% had an AFB1 level below the ML. On the other hand, neither the soybean meal (n=69) nor whole soybean samples (n=64) had an AFB1 level above the ML, 46.4 and 20%, respectively. In 50% (n=10) of cottonseed meal samples, AFB1 level was above the ML; in 20% of wheat middling samples, it was above the ML. Cottonseed and wheat middling samples were used for 2 and 5 months, respectively. AFB1 level in feedstuff showed a significant difference in December (P&lt;0.05) compared with other months, specifically for maize and soybean meal. As the AFM1 level in milk results from AFB1 contaminated feedstuff, our results emphasise the need to implement specific quality measures to reduce contamination.