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.     

The Presence of Aflatoxin M1 in Milk and Milk Products in Bangladesh

As milk provides both micro- and macronutrients, it is an important component in the diet. However, the presence of aflatoxin B₁ (AFB₁) in the feed of dairy cattle results in contamination of milk and dairy products with aflatoxin M₁ (AFM₁), a toxic metabolite of the carcinogenic mycotoxin. With the aim to determine AFM₁ concentrations in milk and milk products consumed in Bangladesh, in total, 145 samples were collected in four divisional regions (Sylhet, Dhaka, Chittagong, and Rajshahi). The samples comprised these categories: raw milk (n = 105), pasteurized milk (n = 15), ultra-high temperature (UHT)-treated milk (n = 15), fermented milk products such as yogurt (n = 5), and milk powder (n = 5). AFM₁ levels in these samples were determined through competitive enzyme-linked immunosorbent assay (ELISA). Overall, AFM₁ was present in 78.6% of milk and milk products in the range of 5.0 to 198.7 ng/L. AFM₁ was detected in 71.4% of raw milk (mean 41.1, range 5.0–198.7 ng/L), and in all pasteurized milk (mean 106, range 17.2–187.7 ng/L) and UHT milk (mean 73, range 12.2–146.9 ng/L) samples. Lower AFM₁ levels were found in yogurt (mean 16.9, range 8.3–41.1 ng/L) and milk powder samples (mean 6.6, range 5.9–7.0 ng/L). About one-third of the raw, pasteurized, and UHT milk samples exceeded the EU regulatory limit (50 ng/L) for AFM₁ in milk, while AFM₁ levels in yogurt and milk powder samples were well below this limit. Regarding regions, lower AFM₁ contamination was observed in Chittagong (mean 6.6, max 10.6 ng/L), compared to Sylhet (mean 53.7, max 198.7 ng/L), Dhaka (mean 37.8, max 97.2 ng/L), and Rajshahi (mean 34.8, max 131.4 ng/L). Yet, no significant difference was observed in AFM₁ levels between summer and winter season. In conclusion, the observed frequency and levels of aflatoxin contamination raise concern and must encourage further monitoring of AFM₁ in milk and milk products in Bangladesh.     

Assessment of aflatoxin M1 levels in pasteurised milk,raw milk,and cheese in Arak,Iran

Aflatoxins are fungal toxins, which may be found in food and due to negative health effects, they are of major concerns for human health and food industries. Aflatoxin M₁ contamination in dairy products in Arak, Iran, 2013 was evaluated using ELISA method. Sample groups were comprised of 111 samples, including pasteurized milk (n?=?56), raw milk (n?=?16) and cheese (n?=?39), and were analyzed for AfM₁ content. The results showed that 93.7% of the samples were positive with the total average concentration of 85.8?µg/L in milk and 30.39?µg/kg in cheese. Moreover, AfM₁ of 94.4% of milk samples and 92.3% of cheese samples was above the standards of Iran and EU.     

On the occurrence of aflatoxin M1 in milk and dairy products

Aflatoxins are toxic fungal metabolites found in foods and feeds. When ruminants eat AFB₁-feedstuffs, they metabolise the toxin and excrete AFM₁ in milk. To control AFM₁ in foods it is necessary to reduce AFB₁ contamination of feeds for dairy cattle by preventing fungal growth and AFB₁ formation in agricultural commodities intended for animal use. Corn and corn-based products are one of the most contaminated feedstuffs; therefore risk factor analysis of AFB₁ contamination in corn is necessary to evaluate risk of AFM₁ contamination in milk and milk products. During the corn silage production, the aflatoxins production is mostly influenced by: harvest time; fertilization; irrigation; pest control; silage moisture; and storage practices. Due to the lower moisture at harvest and to the conservation methods, the corn grain is mostly exposed to the contamination by Aspergillus species. Therefore, it is necessary to reduce the probability of this contaminant through choice of: hybrids; seeding time and density; suitable ploughing and fertirrigation; and chemical or biological control. Grains harvested with the lowest possible moisture and conservation moisture close to or less than 14% are necessary to reduce contamination risks, as is maintaining mass to homogeneous moisture. Kernel mechanical damage, grain cleaning practices and conservation temperature are also factors which need to be carefully controlled.     

Aflatoxin M1 contamination and antibiotic residue in milk in Khorasan province,Iran

The aim of this study was to evaluate aflatoxin M₁ (AFM₁) contamination and antibiotic presence in milk samples in Khorasan province in Iran. During 4 months (March to June 2008), one hundred ninety-six milk samples were collected from seven dairies. The occurrence and concentration range of AFM₁ in the samples were investigated by competitive enzyme-linked immunoabsorbent assay (ELISA) method. Antibiotic presence was determined using Copan test, a broad-spectrum test capable of detecting beta-lactams, tetracyclines, sulfonamides, aminoglycosides and macrolydes. AFM₁ was found in 100% of the examined milk samples by average concentration of 77.92 ng/kg. The concentration of AFM₁ in all of the samples were lower than Iranian national standard and FDA limit (500 ng/L), but 80.6% of the samples had AFM₁ greater than the maximum tolerance limit (50 ng/L) accepted by European Union and Codex Alimentarius Commission. Statistical evaluation showed no significant difference between the mean concentrations of AFM₁ of milk samples taken from different factories (P > 0.05). Copan milk test was positive for 40.8% of the samples.     

AFM1 in Milk: Physical,Biological, and Prophylactic Methods to Mitigate Contamination

Aflatoxins (AFs) are toxic, carcinogenic, immunosuppressive secondary metabolites produced by some Aspergillus species which colonize crops, including many dietary staple foods and feed components. AFB₁ is the prevalent and most toxic among AFs. In the liver, it is biotransformed into AFM₁, which is then excreted into the milk of lactating mammals, including dairy animals. AFM₁ has been shown to be cause of both acute and chronic toxicoses. The presence of AFM₁ in milk and dairy products represents a worldwide concern since even small amounts of this metabolite may be of importance as long-term exposure is concerned. Contamination of milk may be mitigated either directly, decreasing the AFM₁ content in contaminated milk, or indirectly, decreasing AFB₁ contamination in the feed of dairy animals. Current strategies for AFM₁ mitigation include good agricultural practices in pre-harvest and post-harvest management of feed crops (including storage) and physical or chemical decontamination of feed and milk. However, no single strategy offers a complete solution to the issue.     

Occurrence of aflatoxin M1 in some samples of UHT,raw & pasteurized milk from Indian states of Karnataka and Tamilnadu

Aflatoxin M₁ (AFM₁) is a toxic metabolite found in the milk of lactating animals which have consumed feedstuffs contaminated with aflatoxin B₁. Ultra high temperature treated (UHT) milk is a product which is becoming popular in developing countries like India as there is a lack of proper cold storage or refrigeration facilities. In this study, 45 samples of UHT milk of popular brands prevalent in the market were analyzed for the presence of AFM₁ by reversed phase HPLC using fluorescent detector after cleanup of sample with immunoaffinity columns. All samples of plain UHT milk were positive for AFM₁ and 38% of these contained levels more than 0.5 μg/kg, the maximum permitted limit prescribed by the Codex Alimentarius Commission and by the mandatory regulations of the country, the FSSAI Regulations, 2011. In 62.5% of flavored UHT milk, AFM₁ was below detectable levels (0.02 μg L⁻¹). However, 12.5% of these samples also contained levels exceeding the maximum permitted limits. AFM₁ was present in 61.6% of the 52 raw milk samples analyzed from the two states of Karnataka and Tamilnadu with a range of 0.1–3.8 μg L⁻¹. 17.3% of these samples also exceeded the regulatory limits of the country.     

Aspergillus flavus and Total Aflatoxins Occurrence in Dairy Feed and Aflatoxin M1 in Bovine Milk in Aguascalientes,Mexico

Contamination of food chains by toxigenic fungi and aflatoxins is a global problem that causes damage to human health, as well as to crop and livestock production. The objective is to evaluate Aspergillus flavus and total aflatoxins (AFs) occurrence in totally mixed rations (TMRs) for dairy cows and aflatoxin M₁ (AFM₁) in milk for human consumption. Ninety-nine dairy production units located in Aguascalientes, Mexico, were randomly selected, and samples were collected from TMRs, raw milk, and milk marketed in the city in two consecutive agricultural cycles. AFs were quantified in TMRs and milk by indirect enzyme immunoassay and HPLC; aflatoxigenic and molecular (PCR) capacity of monosporic A. flavus isolates in the feed was characterized. All feed, raw, and pasteurized milk samples showed aflatoxin contamination (26.0 ± 0.4 µg/kg, 32.0 ± 1.0, and 31.3 ± 0.7 ng/L, respectively), and a significant proportion (90.4, 11.3, and 10.3%) exceeded the locally applied maximum permissible limits for feed and milk (20.0 µg/kg and 50 ng/L). Aflatoxin contamination in both TMRs and milk indicated a seasonal influence, with a higher concentration in the autumn–winter cycle when conditions of higher humidity prevail. The results obtained suggest the existence of contamination by aflatoxigenic A. flavus and aflatoxins in the diet formulated for feeding dairy cows and, consequently, in the dairy food chain of this region of the Mexican Highland Plateau.     

Exposure of Rat Offsprings to Aflatoxin Risks Through Suckling Mothers Dosed with aflatoxin B1

Abstract

One source of human exposure to aflatoxins is by ingestion of aflatoxins carried over from feeds into milk and milk products such as cheese and powdered milk, where they appear mainly as aflatoxin M. We carried out a study using rats to establish whether milk from lactating rat mothers dosed with aflatoxin B₁ carried over potent aflatoxin metabolites capable of inducing liver cancer in their offsprings. The results of this study demonstrated that the presence of such metabolites of aflatoxin B₁ in milk and milk products presents serious health hazards especially to children consuming milk from dairy cows feeding on aflatoxin B₁ contaminated animal feeds. As much emphasis, therefore, should be placed on the control regulations on the presence of aflatoxin in animal feeds as is placed on its direct contamination of cereals and nuts.     

Determination of aflatoxin M1 levels in Iranian white and cream cheese

A screening survey on the occurrence of aflatoxin M1 (AFM1) was accomplished on 210 cheese samples composed of white cheese (116 samples) and cream cheese (94 samples) purchased from popular markets in central part of Iran (Esfahan and Yazd provinces). The quantitative analysis of AFM1 levels in the samples was performed by using the competitive enzyme-linked immunosorbent assay (ELISA) technique. Aflatoxin M1 at measurable level (50 ng/kg) was detected in 161 (76.6%) samples, consisting of 93 (80.1%) white and 68 (72.3%) cream cheese samples. The concentration of AFM1 in the samples ranged from 52.1 to 785.4 ng/kg. Comparing to legal regulation (250 ng/kg) accepted by some of the countries, 24.2% of the samples exceeded the accepted limit. Among these, the AFM1 levels in 28.4% of white and 19.1% of cream cheese samples were not in accordance with the safety limit. The results indicated that contamination of the samples with AFM1 in such a level appear to be a potential hazard for public health. This paper represents the data of the first survey on the occurrence of AFM1 in cheeses consumed in central part of Iran.     

Adsorbents Reduce Aflatoxin M1 Residue in Milk of Healthy Dairy Cow Exposed to Moderate Level Aflatoxin B1 in Diet and Its Exposure Risk for Humans

This study investigated the effect of moderate risk level (8 µg/kg) AFB₁ in diet supplemented with or without adsorbents on lactation performance, serum parameters, milk AFM₁ content of healthy lactating cows and the AFM₁ residue exposure risk in different human age groups. Forty late healthy lactating Holstein cows (270 ± 22 d in milk; daily milk yield 21 ± 3.1 kg/d) were randomly assigned to four treatments: control diet without AFB₁ and adsorbents (CON), CON with 8 μg/kg AFB₁ (dry matter basis, AF), AF + 15 g/d adsorbent 1 (AD1), AF + 15 g/d adsorbent 2 (AD2). The experiment lasted for 19 days, including an AFB₁-challenge phase (day 1 to 14) and an AFB₁-withdraw phase (day 15 to 19). Results showed that both AFB₁ and adsorbents treatments had no significant effects on the DMI, milk yield, 3.5% FCM yield, milk components and serum parameters. Compared with the AF, AD1 and AD2 had significantly lower milk AFM₁ concentrations (93 ng/L vs. 46 ng/L vs. 51 ng/L) and transfer rates of dietary AFB₁ into milk AFM₁ (1.16% vs. 0.57% vs. 0.63%) (p < 0.05). Children aged 2–4 years old had the highest exposure risk to AFM₁ in milk in AF, with an EDI of 1.02 ng/kg bw/day and a HI of 5.11 (HI > 1 indicates a potential risk for liver cancer). Both AD1 and AD2 had obviously reductions in EDI and HI for all population groups, whereas, the EDI (≥0.25 ng/kg bw/day) and HI (≥1.23) of children aged 2–11 years old were still higher than the suggested tolerable daily intake (TDI) of 0.20 ng/kg bw/day and 1.00 (HI). In conclusion, moderate risk level AFB₁ in the diet of healthy lactating cows could cause a public health hazard and adding adsorbents in the dairy diet is an effective measure to remit AFM₁ residue in milk and its exposure risk for humans.     

Aflatoxin M1 levels in UHT milk and kashar cheese consumed in Turkey

In the present study, 100 UHT milk and 132 kashar cheese samples were analyzed for aflatoxin M1 (AFM1). They were obtained from retail outlets in five big cities (Istanbul, Izmir, Konya, Tekirdag, Edirne). The occurrence and concentration range of AFM1 in the samples were investigated by competitive enzyme-linked immunosorbent assay (ELISA) method. Sixty-seven percent of the UHT milk samples and 82.6% of the kashar cheese samples contained AFM1. The positive incidence of AFM1 in the UHT milk samples and the kashar cheese samples ranged from 10 to 630 ng/kg and from 50 to 690 ng/kg, respectively. AFM1 levels in 31 (31%) UHT milk and 36 (27.3%) kashar cheese samples exceeded the maximum tolerable limit of the EC and the TFC. AFM1 levels in the samples show that there is a presence of high aflatoxin level that constitutes a human health risk in Turkey. Therefore milk and dairy products have to be controlled continuously for presence of AFM1 contamination by the Turkish public health authorities.     

Determination of aflatoxin B1 levels in Iranian rice by ELISA method

This study was carried out to detect the presence of aflatoxin B₁ (AFB₁) in 40 samples of Tarom rice from Iran. Enzyme-linked immunosorbent assay (ELISA) was applied to analyze AFB₁ in the samples. All the analyses were conducted twice. Aflatoxin B₁ was found in all rice samples, the concentration of AFB₁ ranged from 0.29 to 2.92?µg/kg. The AFB₁ concentration mean in the rice samples produced in 2013 was higher (P < 0.05) than the findings in rice in 2012.. However, 25 of the 40 samples exceeded the maximum prescribed limit, i.e. 2?µg/kg of European Union Regulations and also none of the samples reached the maximum prescribed limit 5?µg/kg of the Institute of Standards and Industrial Research of Iran (ISIRI) for aflatoxin B₁. Although, rice is ranked the second among cereal staples consumed food in Iran and many countries, it can make a serious health problem for people even for a small amount of aflatoxin.     

Determination of aflatoxin B1 levels in Iranian and Indian spices by ELISA method

Abstract

This study was carried out to detect the presence of aflatoxin B₁ (AFB₁) in 36 samples of spices from Iran and India that include chilli powder (n?=?12), black pepper powder (n?=?12) and whole black pepper (n?=?12). Enzyme-linked immunosorbent assay was applied to analyse AFB₁ in the samples. All the analyses were done twice. AFB₁ was found in all the spices samples, the concentration of AFB₁ in Iranian samples was ranged from 63.16 to 626.81?ng/kg and in Indian samples was ranged from 31.15 to 245.94?ng/kg. The mean of AFB₁ concentration in the chilli powder was significantly higher (p?<?0.05) than the whole and powdered black pepper. However, none of the samples exceeded the maximum prescribed limit, that is 5000?ng/kg (5?µg/kg) of European Union regulations for AFB₁. Although, the present research was not a comprehensive study; however, it provides valuable information on AFB₁ levels in Iranian and Indian spices.     

Determination of Urinary Biomarkers for Assessment of Short-Term Human Exposure to Aflatoxins in S?o Paulo,Brazil

In the present study, a longitudinal assessment was carried out to evaluate the short-term human exposure to aflatoxins in Pirassununga region, São Paulo, Brazil, by determination of urinary aflatoxins by a liquid chromatography coupled to mass sprectrometry (UPLC-MS/MS) method. Sixteen volunteers with ages ranging from 14 to 55 years old were instructed to collect the early morning first urine four times every three months, from June 2011 to March 2012, totaling 64 samples. Aflatoxin M₁ (AFM₁) was found in 39 samples (61%) at levels ranging from 0.19 to 12.7 pg·mg⁻¹ creatinine (mean: 1.2 ± 2.0 pg·mg⁻¹ creatinine). Residues of aflatoxins B₁, B₂, G₁, G₂ and aflatoxicol were not identified in any urine sample. No significant difference was found among the AFM₁ mean levels in urine samples collected in the four sampling periods. The levels of AFM₁ found in urine samples indicate a low short-term exposure of the population studied to aflatoxins through the diet, although further investigations are needed to assess other long-term biomarkers of exposure to AFB₁.     

Occurrence of aflatoxin B1 contamination in dairy cows feed in Iran

Aflatoxins (AFs) are secondary toxic metabolites produced by fungal species. Occurrence of aflatoxin B1 (AFB1) was determined in 210 dairy cow feed samples consisting of concentrate (n=?70), corn silage (n =?70) and alfalfa hay ( n=?70) obtained from dairy farms in central part of Iran during July–September 2014. AFB1 analysis was carried out by using the competitive enzyme-linked immunosorbent assay technique for screening and high performance liquid chromatography for confirmatory purpose. AFB1 was detected in 88 analyzed samples (41.9%), ranging from 1.87 to 19.41?μg/kg; and 70 samples (33.3%) had levels of the toxin above the Iranian national standard and European Commission limits (5?μg/kg). The frequencies of AFB1 contamination in the samples were as follows: alfalfa hay, 55.7%; concentrate, 44.3% and corn silage, 25.7%. The high occurrence of AFB1 contamination may be attributed to poor harvesting technique, environmental conditions, insect infestation or unsuitable storage conditions. Hence, the contamination with AFs could be a potential hazard for human and animal health.     

Aflatoxin M1 contamination in pasteurized milk in Tabriz (northwest of Iran)

Aflatoxin M1 (AFM1) appears in milk as a direct result of the ingestion of food contaminated with aflatoxin B1 by cattle. The role of milk in human nutrition is well-known. The aim of this study was to evaluate Aflatoxin M1 contamination in pasteurized milk samples in Tabriz city (Iran) by ELISA (Enzyme Linked Immunosorbent Assay). Fifty pasteurized milk samples from different supermarkets in Tabriz city were collected during 6 months (July to December 2008). AFM1 was found in 100% of the examined milk samples. Sixty-two percent of the samples had AFM1 greater than the maximum tolerance limit (50 ng/l) accepted by European Union. It can be concluded that AFM1 levels in the samples purchased in Tabriz city, appear to be a serious public health problem at the moment. To achieve a low level of AFM1 in milk, dairy cows’ feed samples from various cows’ herds must be controlled periodically for aflatoxin and kept away from fungal contamination as much as possible.     

Occurrence of Staphylococcus aureus on Farms with Small Scale Production of Raw Milk Cheeses in Poland

This paper describes the results of a 3-year study on the prevalence, enterotoxinogenicity and resistance to antimicrobials of S. aureus isolated on dairy farms with small scale production of raw cow milk cheeses. The samples of raw milk, semi-finished products and the final products as well as swabs were collected between 2011 and 2013 from nine dairy farms in Poland. A total of 244 samples were examined, of which 122 (50.0%) were contaminated with S. aureus including 18 of 26 (69.2%) mature cheese samples with log10 CFU g⁻¹ between <1- and 7.41. In swabs collected from the staff and production environment the highest contamination rate with coagulase positive staphylococci (CPS) was detected on hands of cheese makers (4.34 log10 CFU/swab). None of the cheese samples contaminated with CPS contained staphylococcal enterotoxins (SEs). However, 55 of 122 (45.1%) S. aureus isolates possessed SEs genes, mainly (26 of 55; 47.3%) a combination of the sed, sej and ser genes. Furthermore, the sep (15 of 55; 27.3%) as well as seg and sei (9 of 55; 16.4%) genes were also identified. The remaining S. aureus isolates possessed the sea gene (one isolate), the combination of sec, seg and sei (three isolates) as well as the sed, sej, sep and ser markers together (one CPS). Resistance to penicillin (62 of 122 isolates; 50.8%) was the most common among the tested isolates. Some CPS were also resistant to chloramphenicol (7; 5.7%) and tetracycline (5; 4.1%). The obtained results indicated that the analyzed cheeses were safe for consumers. To improve the microbiological quality of traditional cheese products more attention should be paid to animal welfare and hygiene practices during the process of cheese manufacturing in some dairy farms.     

Infants exposure to aflatoxin M1 as a novel foodborne zoonosis

Occurrence of aflatoxin M₁ (AFM₁) in infant formula milk powder (IFMP) and maternal breast milk (MBM) was investigated as a risk factor affects the health of newborns in Egypt. A total of 125 IFMP and 125 MBM samples were collected and examined for the presence of AFM₁ using competitive ELISA test. The results indicated that the relative risk (RR) of exposure to AFM₁ via consumption of MBM was higher than IFMP (RR; 1.6, 95% CI; 1.28–2.03, p = 0.0001). The mean concentrations of AFM₁ were significantly differed (p < 0.0001) between MBM (74.413 ± 7.070 ng/l) and IFMP (9.796 ± 1.036 ng/l). High frequency distributions were detected within the range of 5–25 ng/l and >50–100 ng/l in IFMP and MBM, respectively. The average daily exposure of newborns to AFM₁ via consumption of MBM and IFMP was 52.684 and 8.170 ng, respectively, with a significant difference at p < 0.0001. Consumption of raw milk by lactating mothers exhibited a significant correlation (p < 0.0001) with the presence of AFM₁ in their milk. In conclusion, this work established a pioneering concept that AFM₁ may be considered as an etiological factor for a novel foodborne zoonosis identified as Aflatoxicosis M₁.     

Fate of aflatoxin M1 in Iranian white cheese processing

Aflatoxin M₁ (AFM₁) is an important mycotoxin frequently found in milk and dairy products. AFM₁ is a major metabolic product of Aflatoxin B₁ and is usually excreted in the milk and urine of dairy cattle that have consumed aflatoxin-contaminated feed.

The aim of this study was to determine the AFM₁ concentration in curd and whey of Iranian white cheese. The cheese milk samples were artificially contaminated with AFM₁ in six levels (0.25, 0.5, 0.75, 1, 1.25, and 1.75 μg L⁻¹). Cheese was produced according to Iranian traditional recipe. AFM₁ distribution between curd, whey and cheese was determined by high performance liquid chromatography (HPLC) using immunoaffinity column clean up and florescence detection. AFM₁ was recovered in whey, curd and cheese in the concentrations of 0.43, 1.47 and 1.57 μg L⁻¹,respectively. The level of Aflatoxin M₁ in curd and cheese obtained 3.12- and 3.65-fold more than that in whey that shows the affinity of Aflatoxin M₁ to the protein fraction of milk.