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 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.     

Presence of aflatoxin M1 in milk and infant milk products in Tehran,Iran

Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic compounds. The purpose of this survey was to determine natural occurrence and level of AFM₁ in pasteurized liquid milk, infant formula and milk-based cereal weaning food consumed in Tehran, Iran.A total of 328 branded milk products and liquid milk samples were collected and investigated by Enzyme Linked Immuno Sorbent Assay (ELISA).The samples of pasteurized liquid milk (n = 128), infant formula (n = 120) and milk-based cereal weaning food (n = 80) showed that the incidence of contamination with AFM₁ is 96.3%, the presence of AFM₁ in each group was 72.2 ± 23.5, 7.3 ± 3.9 and 16.8 ± 12.5 ng/kg, ranging between 31–113, 1–14 and 3–35 ng/kg, respectively.In general, the amount of AFM₁ in 100 (78%) of liquid milk samples and 24 (33%) of milk-based weaning food was higher than the maximum tolerance limit accepted by European Union, but in all of the infant formula samples was lower (European Communities and Codex Alimentarius has prescribed a limit of 50 ng/kg for AFM₁ in milk and 25 ng/kg in infant milk products).     

Estimate of aflatoxin M1 exposure in milk and occurrence in Brazil

The presence of aflatoxin M₁ (AFM₁) was investigated in 125 samples of powdered milk, pasteurized milk and ultra high treated (UHT) milk in the city of São Paulo, and estimates of AFM₁ intake were assessed. The samples were analysed using an immunoaffinity column for cleanup and a HPLC-FLD for determining AFM₁. The quantification limit was 10 ng/kg. AFM₁ was found in 119 (95.2%) at levels ranging from 10 to 200 ng/kg with mean concentration of 31 ng/kg. The average daily intake estimated for AFM₁ was 1 ng/kg bw per day for children and 0.188 ng/kg bw per day for 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.     

Changes in the concentration of aflatoxin M1 during manufacture and storage of White Pickled cheese

In this study White Pickled cheese was produced from cow’s milk contaminated artificially with aflatoxin M₁ (AFM1) at two different levels, 1.5 and 3.5 μg/kg (ppb), and the effects of process stages on the AFM1 contents were investigated. Pasteurization at 72 °C for 2 min caused losses of AFM1 about 12% and 9%, respectively, in milk contaminated with 1.5 μg/kg AFM1, and 3.5 μg/l AFM1. These losses were found to be statistically significant (P < 0.01). After the cheese production, about 56% and 59% of total AFM1 remained in cheese–curd while about 32% of total AFM1 transferred to the whey for both 1.5 μg/kg and 3.5 μg/kg AFM1 contaminated milk. After 3-month storage in brine, AFM1 content of cheeses produced from 1.5 and 3.5 μg/kg AFM1 contaminated milks decreased by 2.9% and 2.8%, respectively. Changes in AFM1 content of cheese samples were found statistically insignificant (P > 0.05 and P > 0.01) for 3-month storage periods.     

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 pasteurised,UHT milk and milk powder from goat origin

In the present study, 36 samples of pasteurised, ultra-high-temperature (UHT) treated and goat milk powder traded in the city of Campinas, Brazil, were analysed for aflatoxin M₁ (AFM₁), from October to December 2004 and March to May 2005. Results showed 25 (69.4%) positive samples for AFM₁ at levels of 0.011–0.161 μg L⁻¹ of milk, which were below the tolerance limit of 0.500 μg L⁻¹ as adopted for AFM₁ in milk by Brazilian regulations. Mean levels of AFM₁ in pasteurised, UHT and goat milk powder were 0.072 ± 0.048, 0.058 ± 0.044 and 0.056 ± 0.031 μg L⁻¹, respectively. It is concluded that the incidence of AFM₁ in goat milk traded in Campinas is high, but at levels that probably leads to a non-significant human exposure to AFM₁ by consumption of goat milks.     

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 in raw,pasteurized and powdered milk available in the Syrian market

The incidence of contamination of aflatoxin M1 (AFM1) in milk samples collected from the Syrian market was investigated by using the competitive enzyme linked immunosorbent assay (ELISA) technique. A total of 126 samples composed of raw cow milk (74 samples), raw sheep milk (23), raw goat milk (11), pasteurized cow milk (10) and powdered milk (8) showed that 80% of tested samples were contaminated with various levels of AFM1 ranging from >20 to 765 ng/l. Percentages of AFM1-contaminated samples exceeding the American, Syrian and European tolerance limits were 22%, 38% and 52%, respectively.The range of contamination was relatively higher in pasteurized milk than in raw cow and sheep milk. 80% of AFM1-contaminated pasteurized cow milk samples exceeded the European tolerance limit with a range of contamination between 89 and 765 ng/l. Percentages of contaminated raw cow, sheep and goat milk exceeding the European tolerance limit were 59%, 24% and 14%, respectively.Milk powder was almost free of AFM1 contamination with only one sample containing a concentration lower than the European tolerance limit (12 ng/l).Extrapolation of aflatoxin B1 (AFB1) from AFM1 levels of contamination in milk samples indicates that contamination in dairy cattle feeds may range from 0.5 to 47.8 μg/kg.     

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.     

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.     

Aflatoxin M1 in raw milk in Croatia

In this study the levels of aflatoxin M₁ (AFM₁) of 61 milk samples delivered from small milking farms were determined in January, February, March and April (winter–spring season), and June, July and September (summer–autumn season) of 2009. The AFM₁ concentration was determined by competitive enzyme-immunoassay method. The maximum mean concentrations of AFM₁ recorded in winter–spring season were in the range of 35.8–58.6 ng/l and in summer–autumn season in the range of 11.6–14.9 ng/l. The AFM₁ levels determined in January, February, March and April were significantly higher in accordance with concentration of AFM₁ in June, July and September (P < 0.05 to P < 0.0001, respectively). Also, there was significant difference (P < 0.0001) between the mean concentrations of AFM₁ in samples taken all together in winter–spring and summer–autumn season. Only in one sample delivered in February the level of AFM₁ was higher than the maximum tolerance limit (50 ng/l). Therefore, it was concluded that in 98.4% of milk samples in Croatia the levels of AFM₁ were below maximum tolerance level accepted by the European Union.     

Aflatoxin M1 in milk and traditional dairy products from west part of Iran: Occurrence and seasonal variation with an emphasis on risk assessment of human exposure

In the present study, a total of 358 samples consisting of raw milk of cow (n = 64), goat (n = 56) and sheep (n = 52); traditional cheese (n = 40), yoghurt (n = 42), Kashk (n = 40), Doogh (n = 44) and Tarkhineh (n = 20) were analyzed for aflatoxin M₁ (AFM₁) by using an enzyme linked immunosorbent assay (ELISA). Frequency of AFM₁ and its concentration ranges in the ELISA positive samples were determined by high performance liquid chromatography with fluorescence detection (HPLC-FD). AFM₁ contamination was 84.3%, 44.6% and 65.3% for cow, goat and sheep raw milks, respectively. Moreover, AFM₁ was in 65.5%, 23.8%, 14%, 13.6% and 35.0% of cheese, yoghurt, Kashk, Doogh and Tarkhineh samples, respectively. Percentages of cow milk, goat milk, sheep milk and cheese samples exceeding the EU limit were 35.9%, 11.1%, 26.9% and 10%, respectively. HPLC analyses confirmed the ELISA results although the percentages of AFM₁ contamination in raw milk and dairy products were lower than that of ELISA. There were significant differences (P < 0.05) between the mean AFM₁ contents of raw milk, cheese and yoghurt samples during winter and summer seasons. Our study demonstrated that there is a potential risk for liver cancer due to the consumption of milk and dairy products in Iranian consumers.     

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.     

Levels of aflatoxin M1 in milk,cheese consumed in Kuwait and occurrence of total aflatoxin in local and imported animal feed

A total of 321 milk samples (177 fresh, 105 long-life and 27 powdered milk, and 12 human milk), 40 cheese samples and 84 feed samples were analyzed for aflatoxin M1 (AFM1) and total aflatoxin. The samples were collected randomly during January 2005–March 2007, from Kuwaiti markets. The method used was ELISA technique. Results showed that all fresh milk samples except one were contaminated with AFM1 ranging from 4.9 to 68.7 ng/kg. Eight samples exceeded the EC’s regulatory limit. For the long-life milk samples, the ranges of AFM1 were from below the detection limit to 88.8 ng/kg, with four samples above the action limit of the EC. In the powdered milk samples, AFM1 ranged from 2.04 to 4.14 ng/kg. Of the human milk samples, only five were contaminated, with AFM1 levels ranging from 8.83 to 15.2 ng/kg with a mean 9.7 ng/kg. The cheese samples recorded 80% contamination with AFM1 with a range 23.8–452 and mean of 87.6 ng/kg, with one sample being above the regulatory limit (250 ng/kg) while the feed samples, showed 79.8% contamination with total aflatoxin.     

A sensitive and validated method for determination of melamine residue in liquid milk by reversed phase high-performance liquid chromatography with solid-phase extraction

A sensitive and validated method for the determination of melamine residue in liquid milk is developed using reversed phase high-performance liquid chromatography-diode array detection (RP-HPLC-DAD) with solid-phase extraction (SPE). The conditions of the extraction, SPE and HPLC were investigated and optimized. The linearity is satisfactory in the range of 0.1–50 μg/mL with a correlation coefficient of 0.9998. Under the optimal conditions, the method limit of detection (LOD) and method limit of quantification (LOQ) were 18 μg/kg and 60 μg/kg, respectively. The recovery of melamine for milk samples spiked with 0.10–3 mg/kg was in the range of 85.5–99.3% with the RSDs (n = 3) of 2.3–3.7%. The intra-day assay precision (RSD) was 5.6% for five replicates of quality control milk sample at 2 mg/kg level. Confirmation of the identities of melamine was achieved by monitoring the two transitions in multiple-reaction monitoring (MRM) mode, and has been applied successfully for the determination of melamine residue in liquid milk samples. The confirmatory method can permit the detection of melamine residues at levels as low as 60 μg/kg in different liquid milks.     

Assessment of benzoic acid levels in milk in China

Benzoic acid is the most commonly used preservative in foodstuffs. Although benzoic acid is generally recognized as safe (GRAS), adverse effects such as asthma, urticaria, metabolic acidosis and convulsions were observed at low doses in sensitive persons. Some weak clastogenic activity was noted in in vitro assays. The aim of our study was to determine the levels of benzoic acid in milk samples consumed in the city of Guangzhou, China. In this study, 142 samples of pasteurized milk (24), ultra high temperature milk (UHT, n = 45), milk powder (n = 31) and infant formula (n = 42) were analyzed by high performance liquid chromatograph (HPLC) with diode array detector (DAD) from October 2006 to January 2007. Benzoic acid was detected in 109 (76.8%) samples, ranging from 0.51 to 111 mg/kg. The LOD for benzoic acid was, respectively, 0.2 mg/kg in pasteurized and UHT milk, 2 mg/kg in milk powder and infant formula. The mean recoveries of spiked samples at 4 levels were 99.5 ± 3.1% in liquid milk, and 98.5 ± 4.3% in milk powder, respectively. The results show that benzoic acid widely occurs in milk and milk products in China at the low levels. The levels found are not high, and should not affect the general public; however, it may affect the infants and/or sensitive persons. Therefore, it is important to assess the levels of benzoic acid in milk in China. Meanwhile, it should be noted that the lowest percentage of positive samples in pasteurized milk probably results from the difference in the quality of raw milk, processing technical and storage condition of milk products.