Occurrence of aflatoxin M1 in white cheese samples from Tehran, Iran

This study was undertaken to determine the occurrence of aflatoxin M₁ (AFM₁) in 50 white cheese samples from 2 dairy factories in summer 2008 and winter 2009. Enzyme-linked immunosorbent assay (ELISA) method was used for analysis of the samples. Aflatoxin M₁ was found in 60% of the cheese samples, ranging from 40.9 to 374 ng/kg. Toxin levels in 6% of the samples exceeded the Iranian national standard limit i.e. 200 ng/kg. Considering seasonal variability, mean concentration of AFM₁ in the samples collected in winter was significantly (P < 0.03) higher than those collected in summer. Therefore, high occurrence of AFM₁ in cheese samples could be a potential hazard for public health.     

Occurrence of aflatoxin M1 in dairy products in Brazil

The objective of this study was to investigate the incidence and occurrence of aflatoxin M₁ (AFM₁) in dairy products produced in Brazil. A total of 123 samples of three different groups of dairy products (cheese, yoghurt, and dairy drinks) consumed by Brazilians were collected during 2010. All samples including 58 cheese samples, 53 samples of yoghurt and 12 dairy drinks were purchased from grocery stores in the Ribeirão Preto-SP area. Cheese samples were classified into three categories depending on their moisture and fat contents: Minas Frescal cheese, Minas Frescal light cheese and Minas Padrão cheese. Samples were analyzed for AFM₁ by a published method. The method comprised aqueous methanol extraction, immunoaffinity column purification and isolation, reversed phase liquid chromatography separation and fluorescence detection. AFM₁ was detected in 84% of the analyzed cheese samples (>3 ng/kg) with levels ranging from 10 to 304 ng/kg in 67% of the samples. AFM₁ was detected in 95% of the yoghurt and dairy drink samples with levels ranging from 10 to 529 ng/kg in 72% of the samples. Despite the lack of a Brazilian regulatory limit for AFM₁ in yoghurt and dairy drinks the survey data of this study may offer information useful in the determination of whether the occurrence of AFM₁ in Brazilian dairy products may be considered as a possible risk for consumer health and whether Brazilian regulatory guidelines for AFM₁ in dairy products are needed.     

Variation of aflatoxin M1 contamination in milk and milk products collected during winter and summer seasons

Total 221 samples of milk and milk products were collected during winter (November 2011–February 2012) and 212 samples were collected during summer (May–August 2012) from central areas of Punjab, Pakistan. The samples were analyzed for the presence of aflatoxin M₁ (AFM₁) with a validated HPLC method equipped with florescence detector. The results revealed that from winter season almost 45% samples of milk and milk products were found to be contaminated with AFM₁ i.e. 40% of raw milk, 51% of UHT milk, 37% of yogurt, 60% of butter and 43% of ice cream samples and 27, 24, 25, 34 and 17% of samples were found above the recommended limit for AFM₁, respectively. However, from summer season 32% samples of milk and milk products were found to be contaminated i.e. 36% of raw milk, 31% of UHT milk, 29% of yogurt, 40% of butter and 24% of ice cream and 23, 23, 18, 20 and 5% of samples were found above the permissible limit for AFM₁, respectively. The levels of contamination in winter milk and milk product samples were significantly higher (α ≤ 0.05) than in summer season. The occurrence of AFM₁ in milk and milk products were higher, demanding to implement strict regulations and also urged the need for continuous monitoring of milk and milk products in order to minimize the health hazards.     

Seasonal variation of aflatoxin M1 in raw milk from the Yangtze River Delta region of China

The objective of this study was to evaluate the occurrence of aflatoxin M₁ (AFM₁) in raw milk samples from 18 dairy farms in the Yangtze River Delta region during four different seasons. A total of 72 tank milk samples was collected with 18 samples for each season. Milk AFM₁ was detected using LC-MS/MS. The AFM₁ was detected in 43 milk samples (59.7%) ranging in concentration from 10 to 420 ng/L. The concentration of AFM₁ in raw milk was significantly higher during the winter (123 ng/L) than during other seasons (P < 0.05). There was no significant difference between the spring (29.1 ng/L), summer (31.9 ng/L), and autumn (31.6 ng/L) (P > 0.05) seasons. This indicates that raw milk collected during the winter is at high risk for AFM₁ and that seasonal factors should be considered for the management of aflatoxins in both the feed and milk.     

Occurrence and factors associated with the presence of aflatoxin M1 in breast milk samples of nursing mothers in central Mexico

Aflatoxin M₁ (AFM₁) is the main mycotoxin frequently found in milk and dairy products. Exposure of infants to AFM₁ is of great health public concern because of its toxic and carcinogenic properties. The aim of this study was to determine the occurrence, levels and factors associated with the presence of aflatoxin M₁ in breast milk samples of nursing mothers in central Mexico. A total of 112 samples were collected and analyzed by a competitive-ELISA assay during January–August 2014. A Semi-Quantitative Food Frequency Questionnaire was used to determine weekly intake of food groups. Results showed that 89% of breast milk samples contained AFM₁ in a range of 3.01–34.24 ng/L. AFM₁ mean level was significantly higher (P < 0.05) in winter (12.78 ng/L) and spring (12.09 ng/L) than summer (7.91 ng/L). It was also detected that 7% of samples exceeded the European Community regulation (25 ng/L) for milk infant formula. The presence of aflatoxin M₁ was significantly associated (P < 0.05) to consumption of egg, cola drink and sunflower oil. The high occurrence and noticeable levels of AFM₁ detected, as well as the mean AFM₁ estimated daily intake (2.35 ng/kg b.w./day) suggested, for the first time, that breast-fed infants in the central region of Mexico, may be exposed to significant levels of this toxin through mother's breast milk.     

Variation of levels of aflatoxin M1 in raw milk from different localities in the central areas of Punjab, Pakistan

The occurrence of aflatoxin M₁ (AFM₁) in samples of raw milk of buffaloes and cows from different localities in the central areas of Punjab, the province of Pakistan, was determined by using high-performance liquid chromatography (HPLC) with prior clean-up step applying immunoaffinity columns. The present study has been designed to find out the variation of levels of aflatoxin M₁ in raw milk of different localities. Feed has major role for prevalence of aflatoxin M₁ in milk and different feed regimen is being used in different areas. Total 480 milk samples were analyzed, among these 360 were of buffalo milk and 120 were of cow milk. The percentage of AFM₁ contamination in buffalo milk and cow milk was 42.5% and 52.5%, respectively. The mean value of AFM₁ was 0.027 μg L⁻¹ in buffaloes’ milk and was 0.044 μg L⁻¹ in cows’ milk. In both types of milk, level of AFM₁ concentration was higher in milk samples obtained from urban and semi-urban areas and it was minimal in milk from rural areas.     

Occurrence,seasonal variation and risk assessment of exposure to aflatoxin M1 in Iranian traditional cheeses

A total of 360 traditional cheeses consisted of Lighvan (n = 62), Koozeh (n = 62), Siahmazgi (n = 58), Khiki (n = 58), Talesh (n = 58) and Lactic (n = 62) collected from different parts of Iran were analyzed for aflatoxin M₁ (AFM₁) using an enzyme linked immunosorbent assay (ELISA). Frequency of AFM₁ and its concentration ranges of all the ELISA positive samples were determined by high-performance liquid chromatography with fluorescence detection (HPLC-FD). AFM₁ was detected in 60.3%, 75.8%, 72.4%, 43.5%, 38.7% and 35.4% of Siahmazgi, Khiki, Talesh, Lighvan, Koozeh and Lactic cheeses, respectively with concentration ranging from 50.5 to 308.7 ng/kg, respectively. HPLC analyses confirmed the ELISA results although the rates of contaminated cheese samples were lower than that of ELISA. There was significant difference in AFM₁ level between various cheese types and samples collected from summer and winter seasons (P < 0.05). By comparing our findings with the EU limit, about 10.5% of cheese samples had exceeding values for the toxin. The results of the present study indicates that there is no health risk in consumption of Iranian traditional cheeses due to the presence of AFM₁.     

Screening of aflatoxin M1 occurrence in selected milk and dairy products in Terengganu,Malaysia

The study was conducted to screen the occurrence of aflatoxin M₁ (AFM₁) in 53 selected milk and dairy product samples (11 liquid milk, 12 powdered milk, 8 3-in-1 beverages, 6 condensed sweetened milk, 2 evaporated milk, 7 cultured milk drink, 5 yogurt and 2 cheese samples). These samples were purchased from selected markets in Terengganu, Malaysia in January 2014 based on a questionnaire survey among 212 respondents on the types and brands of milk and dairy products that were frequently consumed. Based on the responses, 53 milk and dairy products were purchased and the competitive enzyme-linked immune-absorbent assay (ELISA) method was used to determine the level of AFM₁ in the samples. Of 53 samples, 19 samples were positive with AFM₁ (35.8%) ranging from 3.5 to 100.5 ng/L. Although 4/53 (7.5%) of the tested samples had the contamination level greater than the European Commission (EC) limit (>50 ng/L), the contamination levels were still below the Malaysia Food Regulation 1985 limit (less than 500 ng/L). This study provided a pioneering data on the occurrence of AFM₁ in milk and dairy products in Malaysia.     

A study on the occurrence of aflatoxin M1 in Iranian Feta cheese

This study was undertaken to determine the presence and levels of aflatoxin M₁ (AFM₁) in cheeses produced by different plants in the province of Tehran. For this purpose, a total of 80 cheese samples analyzed, and thin layer chromatography (TLC) was used to determine the presence and levels of AFM₁.AFM₁ was found in 82.5% of 80 of the cheese samples examined. The range of contamination levels varied among different months. AFM₁ in May, August, November, February samples ranged from 0.17 to 1.30, 0.15 to 2.41, 0.16 to 1.11, and 0.19 to 2.05 μg/kg, respectively, while the mean values were 0.41, 0.35, 0.36, and 0.52 μg/kg, respectively.The highest mean concentration of aflatoxin M₁ (AFM₁) was registered in February samples (0.52 μg/kg). The lowest mean concentration of aflatoxin M₁ was registered in August samples (0.35 μg/kg).Statistical evaluation showed that there were not significant differences (P > 0.05) between the concentrations of AFM₁ of cheese samples taken in May and August with November and February. In other words, AFM₁ contents of cheese samples taken in November and August were not lower than cheese samples taken in May and February. Almost 60.6% of the contaminated samples exceeded the maximum acceptable levels (0.25 μg/kg) that accepted by some of the countries such as Turkey.It was therefore concluded that, high occurrence of AFM₁ in cheese samples were considered to be possible hazards for human health.     

Occurrence of AFM1 in urine samples of a Brazilian population and association with food consumption

This survey evaluated the presence of AFM₁ in human urine samples from a specific Brazilian population, as well as corn, peanut, and milk consumption measured by two types of food inquiry. Urine samples from donors who live in the city of Piracicaba, State of São Paulo, Brazil were analyzed to detect the presence of aflatoxin M₁ (AFM₁), an aflatoxin B₁ metabolite, which may be used as aflatoxin B₁ exposure biomarker. The AFM₁ analysis was performed using immunoaffinity clean-up and detection by high-performance-liquid chromatography with fluorescence detector. A total of 69 samples were analyzed and 45 of them (65%) presented contaminations ⩾1.8 pg ml⁻¹, which was the limit of quantification (LOQ). Seventy eight percent (n = 54) of the samples presented detectable concentrations of AFM₁ (>0.6 pg ml⁻¹). The AFM₁ concentration among samples above LOQ ranged from 1.8 to 39.9 pg ml⁻¹. There were differences in food consumption profile among donors, although no association was found between food consumption and AFM₁ concentration in urine. The high frequency of positive samples suggests exposure of the populations studied to aflatoxins.     

Aflatoxin M1 in milk and distribution and stability of aflatoxin M1 during production and storage of yoghurt and cheese

The objective of this study was to investigate the incidence and occurrence of aflatoxin M₁ (AFM₁) in Brazilian milk and infant formula. The distribution and stability of AFM₁ in cheese and yoghurt were also determined. Milk samples and infant formula samples were purchased in Ribeirão Preto-SP, Brazil and were analyzed for AFM₁ using immunoaffinity column purification, liquid chromatography separation and fluorescence detection. AFM₁ was detected in 83% of the milk samples (>3 ng/kg) with levels ranging from 8 to 437 ng/kg for fluid milk, and 20–760 ng/kg for powdered milk. No AFM₁ was found in infant formula. Processing and storage was shown to have little effect on AFM₁ content in milk and milk products. Total AFM₁ mass in milk was reduced by 3.2% in cheese and by 6% in yoghurt (pH 4.4). The mean concentration of AFM₁ in curds was 1.9-fold higher and whey was 0.6-fold lower than in unprocessed milk.     

Aflatoxin M1 contamination in white and Lighvan cheese marketed in Rafsanjan,Iran

This study was a screening survey to determine the occurrence of aflatoxin M₁ (AFM₁) in 82 cheese samples composed of white cheese (45 samples) and Lighvan cheese (37 samples) obtained from supermarkets and retail outlets in Rafsanjan city of Iran. The competitive enzyme immunoassay method was used for determination of the toxin in the samples. Aflatoxin M₁ was detected in 39 (47.6%) samples, consisting of 29 (64.4%) white cheese (mean: 135 ng/kg; range: 93.3–309 ng/kg) and 10 (27%) Lighvan cheese samples (mean: 90.8 ng/kg; range: 70.5–203 ng/kg). According to Iranian national standard limit for AFM₁ in cheese (200 ng/kg), 9 samples (20%) of white cheese and 1 sample (2.70%) of Lighvan cheese had levels above the limit. It was concluded that the contamination of the samples with AFM₁ in such a level could be considered as a serious public health problem.     

Contamination of UHT milk by aflatoxin M1 in Iran

In this study the levels of aflatoxin M₁ (AFM₁) in UHT milk samples were determined in May, August and November and February. Two hundred and ten UHT milk samples were obtained from supermarkets in Tehran, Iran. The occurrence and concentration range of AFM₁ in the samples were investigated by competitive enzyme-linked immunoabsorbent assay (ELISA) method. AFM₁ was found in 116 (55.2%) of 210 UHT milk samples examined. The levels of AFM₁ in 70 (33.3%) samples were higher than the maximum tolerance limit (0.05 μg/l) accepted by some European countries while none of the samples exceeded the prescribed limit of US regulations. The highest mean concentration of AFM₁ was recorded in February (0.087 μg/l). The lowest mean concentration of AFM₁ was recorded in August (0.021 μg/l). Statistical evaluation showed that there were significant difference (P < 0.01) between the mean concentrations of AFM₁ of UHT milk samples taken in February with May and August. AFM₁ contents of milk samples taken in February were not higher than UHT milk samples taken in November (P < 0.01). The AFM₁ incidence of exceeding legal limit in UHT milk samples (33.3%) was relatively much higher than some other countries. It was therefore concluded that, the levels of AFM₁ in UHT milk samples consumed in Iran were high and seemed to pose a threat to public health.     

Aflatoxin M1 and ochratoxin A in human milk in Ribeirão Preto-SP,Brazil

The objective of this study was to determine the extent of aflatoxin M₁ (AFM₁) and ochratoxin A (OTA) contamination in human breast milk in the city of Ribeirão Preto, São Paulo State, Brazil. During 2012, 100 samples of human milk were collected at the local Human Milk Bank. The method comprised, immunoaffinity column purification and isolation, liquid chromatography separation and fluorescence detection. The average percentage recoveries of AFM₁ and OTA spiked at 20 and 50 ng/L in control human milk were 78.1 ± 11.7% and 73.7 ± 9.6%, respectively. The average relative standard deviations of AFM₁ and OTA spiked at the same levels were 11.7 and 9.6% respectively. The limits of detection was 0.3 ng/L for AFM₁ and OTA. The limit of determination was 0.8 ng/L for both mycotoxins. This method was used to analyze 100 human milk samples, of which, two samples were found to contain AFM₁ at level greater than 0.3 ng/L. OTA was detected in 66 samples (66%), wherein 32 were above the limit of detection and 34 were in the range of from 0.8 to 21 ng/L. Results of our study indicate that breast-fed Brazilian infants had only an insignificant exposure to AFM₁ and OTA.     

The seasonal variation of aflatoxin M1 in milk and dairy products and assessment of dietary intake in Punjab,Pakistan

Total 372 samples (169 sample from summer and 203 samples from winter) of milk and dairy products were collected from major cities of Punjab, Pakistan, during 2014–2015. The aflatoxin M₁ (AFM₁) levels were analyzed using HPLC, equipped with floresceⁿce detector. The results have showed that AFM₁ was detected in 77 (45.5%) samples of milk and dairy products from summer at the range of LOD to 229.6 ng/L, and 114 (56.1%) samples from winter at a range of LOD to 345.8 ng/L. The highest mean of AFM₁ i.e. 94.9 ± 5.4 ng/L from summer and 129.6 ± 8.4 ng/L from winter was detected in raw milk samples. The results have shown that 37.5% of milk, 32% of UHT milk, 12.5% of powdered milk, 20% of flavored milk, 20% of yogurt and 16% of flavored milk samples from summer were found exceeded the recommended levels of AFM₁ i.e 50 ng/L (European Union permissible limit), as compared to 38.1%, 37.1%, 15.6%, 21.4%, 27.7% and 40% samples of milk, UHT milk, powdered milk, flavored milk, yogurt and flavored yogurt from winter, respectively. The mean level of AFM₁ in samples of milk, UHT milk and powdered milk samples from winter season has significantly (p˂ 0.05) higher as compared to the mean levels in samples from summer season. The dietary exposures of AFM₁ in milk and dairy products were calculated in five different age groups and the highest level of 3.42 and 3.33 ng/L/day in summer and 4.7 and 4.6 ng/L/day in winter were found in 1–5 years of male and female infants, respectively. The results of present study have shown significant levels of AFM₁ in milk and dairy products from Punjab, Pakistan and could pose considerable thereat to the health of local population.     

Analysis of aflatoxin M1 and M2 in commercial dairy products using high-performance liquid chromatography with a fluorescence detector

Aflatoxin M₁ (AFM₁) and M₂ (AFM₂) in commercial dairy products were analyzed by high-performance liquid chromatography (HPLC) with a fluorescence detector (FLD). To ensure an accurate analysis, two derivatization methods, bromination and aflatoxin–trifluoroacetic acid derivatization (ATD), were compared. The limits of detection (LODs) of the bromination method were 124.42–151.73 ng/kg, and the recovery rates were between 64 and 102%. The detection rates and concentration levels of AFM₁ were 6–74% and 14.48–270.94 ng/kg, respectively. AFM₁ was detected in 74% of milk powder samples and 36% of ice cream samples. The mean values of AFM₁ in milk powder and ice cream samples were 270.94 and 33.16 ng/kg, respectively. In the case of AFM₂, the detection rates were 2–10%, and the concentration levels were 20.62–55.67 ng/kg in milk and milk powder. Among milk and milk powder samples, ultra heat-treated (UHT) milk had lower AFM₁ contamination levels than pasteurized milk.     

Occurrence of aflatoxin M1 in raw milk in South Korea using an immunoaffinity column and liquid chromatography

The level of aflatoxin M₁ (AFM₁) contamination in raw milk produced in South Korea was investigated using immunoaffinity column chromatography and high performance liquid chromatography with fluorescence detector. A total of 100 raw milk samples were collected from 100 cattle ranches located in three different provinces of South Korea. Forty eight out of 100 raw milk samples contained AFM₁ at low level (0.002–0.08 μg/L) with mean value of 0.026 μg/L. Among the AFM₁ contaminated samples, 29 raw milk samples contained only traceable amount of AFM₁ below the limit of LOQ, 0.02 μg/L. None of samples exceeded the maximum level (0.5 μg/L) of Korean regulation for AFM₁ in milk. The limit of detection was 0.002 μg/L. The result of recovery test with 0.5 μg/L AFM₁ in raw milk sample was 96.3% (SD 3.6, n = 5). This is the first pioneering study to investigate the level of AFM₁ in raw milk used in dairy industries in South Korea.     

Aflatoxin M1 in UHT milk consumed in Turkey and first assessment of its bioaccessibility using an in vitro digestion model

Contamination of milk and dairy products with aflatoxin M₁ (AFM₁) continues to receive increased attention because of its potential health hazard to humans. The first aim of this study was to know the occurrence and levels of AFM₁ in whole UHT milk from main processors in Turkey in order to make a preliminary exposure assessment. A total of 40 milk samples were analysed for AFM₁ using high performance liquid chromatography with fluorescence detection (HPLC-FD) after immunoaffinity column clean-up. Aflatoxin M₁ was detected in 20% of samples at levels ranging from <0.004 to 0.076 μg l⁻¹. Only two samples contained AFM₁ above the EU limit of  0.05 μg l⁻¹.The second aim of this study was to determine the bioaccessibility of AFM₁ from milk using an in vitro digestion model. The bioaccessibility of AFM₁ in spiked and naturally contaminated milk samples ranged from 80.5 to 83.8% and from 81.7 to 86.3%, respectively. No difference (P > 0.05) in AFM₁ bioaccessibility was found between spiked and naturally contaminated milk samples. This study also assessed the binding of AFM₁ by six probiotic bacteria under simulated gastrointestinal conditions. A 15.5–31.6% reduction in AFM₁ bioaccessibility was observed in the presence of probiotic bacteria. Based on the results obtained in the present study, the mean daily intake of AFM₁ through milk consumption was estimated as 0.008 ng kg⁻¹ b.w. day⁻¹ for Turkish adults.     

Aflatoxin M1 levels of Turkish white brined cheese

This study was undertaken to determine the presence and levels of aflatoxin M₁ (AFM₁) in Turkish white brined cheese consumed in the province of Erzurum, Turkey. For this purpose, a total of 193 cheese samples were randomly obtained from retail outlets and Enzyme Linked Immunosorbent Assay (ELISA) technique was used to determine the presence and levels of AFM₁. AFM₁ at detectable level (50 ng/kg) was found in 82.4% of the samples. The concentration of AFM₁ in samples ranged from 52 to 860 ng/kg. Of the samples, 26.4% exceed the legal limit of 250 ng/kg established by Turkish Food Codex. It was concluded that widespread occurrence of AFM₁ in Turkish white brined cheese samples were considered to be possible hazards for public health especially children.     

Seasonal variation of aflatoxin M1 contamination in industrial and traditional Iranian dairy products

This study aimed to determine the occurrence of aflatoxin M₁ (AFM₁) contamination in 682 dairy product samples consisting of raw milk of cow, goat and sheep; Lighvan cheese; and industrial and traditional yoghurt, Kashk and Doogh samples collected from popular markets and dairy ranches in four large Iranian cities. Thin layer chromatography (TLC) technique was used for analysis of the samples. Results showed that the incidence and levels of AFM₁ contamination in raw cow milk and industrial products (manufactured from cow milk) were higher than raw goat or sheep milk, and traditional products (made from goat and sheep milk), respectively. Moreover, seasonal variations influenced the concentration of AFM₁ in most of the analyzed dairy products. Owing to the abundance and popularity of the industrial products, contamination of these products in such a level could be a potential hazard for public health.