[On the aflatoxin M1 content of cheese during ripening and storage]

Mycotoxin Monitoring, Regulation and Analysis in India: A Success Story

Mycotoxins are deleterious fungal secondary metabolites that contaminate food and feed, thereby creating concerns regarding food safety. Common fungal genera can easily proliferate in Indian tropical and sub-tropical conditions, and scientific attention is warranted to curb their growth. To address this, two nodal governmental agencies, namely the Agricultural and Processed Food Products Export Development Authority (APEDA) and the Food Safety and Standards Authority of India (FSSAI), have developed and implemented analytical methods and quality control procedures to monitor mycotoxin levels in a range of food matrices and assess risks to human health over the last two decades. However, comprehensive information on such advancements in mycotoxin testing and issues in implementing these regulations has been inadequately covered in the recent literature. The aim of this review is thus to uphold a systematic picture of the role played by the FSSAI and APEDA for mycotoxin control at the domestic level and for the promotion of international trade, along with certain challenges in dealing with mycotoxin monitoring. Additionally, it unfolds various regulatory concerns regarding mycotoxin mitigation in India. Overall, it provides valuable insights for the Indian farming community, food supply chain stakeholders and researchers about India's success story in arresting mycotoxins throughout the food supply chain.

Evaluation of Aflatoxin M1 Enrichment Factor in Semihard Cow's Milk Cheese and Correlation with Cheese Yield

HIGHLIGHTS

The aflatoxin M₁ content in milk was not related to the enrichment factor. The enrichment factor in 45-day ripened semihard cheese was defined. The enrichment factor in cheese is affected by cheese yield.

Occurrence of aflatoxin M(1) in dairy products in southern Italy

A screening survey of the presence of aflatoxin M(1) (AFM(1)) was carried out on 265 samples of cheese made from cow, buffalo, goat, sheep, sheep-goat milk collected in the Apulia region (Southern Italy). Selected samples included unripened, medium and long-term ripened cheeses. AFM(1) was found in 16.6% of the analyzed samples. The highest positive incidence was for medium and long-term ripened cheeses, especially those made from sheep-goat milk, while buffalo cheeses tested consistently negative. Our results show that the level of contamination by AFM(1) in dairy products from Apulia Region are lower than in other Italian and European regions. Moreover, it is important to underline that a common European norm concerning the AFM(1) threshold limits for dairy products is still lacking.

Binding of aflatoxin M1 to different protein fractions in ovine and caprine milk

The affinity of aflatoxin M1 toward the main milk protein fractions in ewe and goat milk was investigated by using an ELISA. This study took into account the possible effects of common dairy processes such as ultrafiltration, acidic or rennet curding, and production of ricotta from acidic or rennet whey. Treatments that allowed the separation of casein from whey proteins under conditions that do not alter the physical or chemical status of the proteins (such as ultracentrifugation) were used as a reference. None of the treatments used in typical dairy processes caused significant release of the toxin, in spite of the relevant changes they induced in the interactions among proteins. Only the combined heat and acidic treatment used for production of ricotta cheese altered the structure of whey proteins to the point where they lost their ability to bind the toxin. This study also showed that, regardless of the physical state of the sample, a commercial electronic nose device, in combination with appropriate statistical tools, was able to discriminate among different levels of sample contamination.

Distribution and stability of Aflatoxin M1during processing and ripening of traditional white pickled cheese

The distribution of aflatoxin M(1) (AFM(1)) has been studied between curd, whey, cheese and pickle samples of Turkish white pickled cheese produced according to traditional techniques and its stability studied during the ripening period. Cheeses were produced in three cheese-making trials using raw milk that was artificially contaminated with AFM(1) at the levels of 50, 250 and 750 ng/l and allowed to ripen for three months. AFM(1) determinations were carried out at intervals by LC with fluorescence detection after immunoaffinity column clean-up. During the syneresis of the cheese a proportionately high concentration of AFM(1) remained in curd and for each trial the level was 3.6, 3.8 and 4.0 times higher than levels in milk. At the end of the ripening, the distribution of AFM(1) for cheese/whey + brine samples was 0.9, 1.0 and 1.3 for first, second and third spiking respectively indicating that nearly half of the AFM(1) remained in cheese. It has been found that only 2-4% of the initial spiking of AFM(1) transferred into the brine solution. During the ripening period AFM(1) levels remained constant suggesting that AFM(1) was quite stable during manufacturing and ripening.

Transfer of Aflatoxin B1 from Feed to Milk and from Milk to Curd and Whey in Dairy Sheep Fed Artificially Contaminated Concentrates

An experiment was carried out using dairy ewes to study the transfer of aflatoxin B1 (AFB1) from feed to milk and from milk to cheese. The effects of AFB1 on liver function and hematological parameters were also investigated. Fifteen ewes were assigned to treatments in replicated 3 x 3 Latin squares. The experimental groups received 32, 64, or 128 microg/d of pure AFB1 for 7 d followed by 5 d of clearance. On the sixth day of the first period, the total daily milk produced by each ewe was collected separately and processed into cheese. The results indicate that the level of AFB1 used did not adversely affect animal health and milk production traits. The aflatoxin M1 (AFM1) concentrations in milk approached a steady-state condition in all treated groups between 2 and 7 d after the start of treatment. The mean AFM1 concentrations of treated groups in steady-state condition (184.4, 324.7, and 596.9 ng/kg in ewes fed 32, 64, or 128 microg of AFB1, respectively) were significantly affected by the AFB1 doses. The AFM1 concentration was linearly related to the AFB1 intake/kg of BW. The carry-over values of AFB1 from feed into AFM1 in milk (0.26 to 0.33%) were not influenced by the AFB1 doses. The AFM1 concentrations in curd and whey were linearly related to the AFM1 concentrations in the unprocessed milk.

Excretion of aflatoxin M1 in milk of dairy ewes treated with different doses of aflatoxin B1

Two experiments were conducted to study the amount of aflatoxin M1 (AFM1) in milk in response to feeding aflatoxin B1 (AFB1). In experiment 1, four dairy ewes in early lactation received a single dose of pure AFB1 (2 mg). Individual milk samples were collected during the following 5 d to measure AFM1 concentration. The average excretion of AFM1 in milk followed an exponential decreasing pattern, with two intermediate peaks at 24 and 48 h. No AFM1 was detected in milk at 96 h after dosing. The mean rate of transfer of AFB1 into AFM1 in milk was 0.032%, with a high individual variability (SD = 0.017%). In experiment 2, 16 dairy ewes in midlactation were divided into four groups that received different daily doses of AFB1 (0, 32, 64, and 128 microgram for control and groups T1, T2, and T3, respectively) for 14 d. Pure AFB1 was administered to each animal divided in two daily doses. Individual milk samples were collected at 12, 24, 36, 48, 72, 96, 144, 216, and 312 h after the first AFB1 administration, during the intoxication period, and every 24 h for 7 d after the withdrawal of AFB1. AFM1 was detected in the milk of all animals of the treated groups at 12 h after the administration of AFB1. In all treated groups, milk AFM1 concentration increased from 12 to 144 h after the beginning of administration. It then decreased, reaching a stable concentration at 216 and 312 h after the first administration. No AFM1 was detected in milk 3 d after the last administration of AFB1. Milk AFM1 concentration measured at steady-state condition was significantly affected by the AFB1 dose (0.031, 0.095, and 0.166 in T1, T2, and T3 groups, respectively), with a linear relationship between AFB1 dose and milk AFM1 concentration (R2 = 77.2%). The carryover (AFM1/AFB1 ratio) was not significantly affected by treatment, and its mean value was 0.112% (SE = 0.011). The carryover was lower than that reported for dairy cattle and goats, suggesting a better ability of sheep to degrade AFB1.

Distribution and stability of aflatoxin M1during processing, ripening and storage of Telemes cheese

Telemes cheeses were produced using milk that was artificially-contaminated with aflatoxin M1 at the levels of 0.050 and 0.100 microg/l. The cheeses produced in the two cheese-making trials were allowed to ripen for 2 months and stored for an additional 4 months to simulate commercial production of Telemes cheese. Concentrations of aflatoxin M1 in whey, curd, brine, and the produced cheeses were determined at intervals by liquid chromatography and fluorometric detection coupled with immunoaffinity column extraction. Concentrations of aflatoxin M1 in the produced curds were found to be 3.9 and 4.4 times higher than those in milk, whereas concentrations in whey were lower than those in curd and milk. Aflatoxin M1 was present in cheese at higher concentrations at the beginning than at the end of the ripening/storage period, and it declined to concentrations 2.7 and 3.4 times higher than those initially present in milk by the end of the sixth month of storage. Concentrations of aflatoxin M1 in brine started low and increased by the end of the ripening/storage period but only a portion of the amounts of aflatoxin M1 lost from cheese was found in the brine. Results showed that Telemes cheeses produced from milk containing aflatoxin M1 at a concentration close to either the maximum acceptable level of 0.05 microg/l set by the European union (EU) or at double this value, will contain the toxin at a level that is much lower or slightly higher, respectively, than the maximum acceptable level of 0.250 microg of aflatoxin M1/kg cheese set by some countries.

[Aflatoxin M1 in type B milk solid in the municipality of São Paulo, SP (Brazil)]

No leite tipo "B", comercializado no Município de São Paulo, SP (Brasil), foi pesquisada a presença de aflatoxina M1. As amostras de leite analisadas foram provenientes das quatro marcas de maior consumo pela população, coletadas no período de julho a outubro de 1982. A aflatoxina M1, embora em baixos níveis e em pequena proporção (1,8%), fez-se presente nas quatro marcas.

Association of aflatoxin M1 with casein

Equilibrium dialysis was used to determine whether aflatoxin M1 (AFM1) binds to casein. Simulated milk ultrafiltrate (SMUF) containing 10 or 20 ng/ml of AFM1 was dialyzed against SMUF containing casein micelles. After 24 h at 7 degrees C, the casein suspension contained 2.5- or 2.9-fold, respectively, more toxin than that found in SMUF. An average of 17.9 or 55.3 micrograms of AFM1, respectively, per gram of casein was bound. In a separate experiment, milk naturally contaminated with AFM1 was treated with a proteolytic enzyme. An average of 30.7% more toxin was found in treated than in untreated milk. This result also suggests binding of AFM1 by milk protein.

Aflatoxin M1 in manufactured dairy products produced in the United States in 1979

In a 1979 survey of manufactured dairy products (992 samples of nonfat dry milk, vanilla ice cream, yogurt, Cheddar cheese, and cottage cheese) for aflatoxin M1 contamination, one sample, a cottage cheese, had detectable aflatoxin equivalent to .08 ng/ml in the milk from which the product was made. Samples were taken by Food and Drug District inspectors from randomly selected establishments at three times throughout the year. The distribution of sample quotas to each District was weighted to double the representation of establishments in the southern tier of states. The conclusion from this survey is that in a "normal" year aflatoxin M1 should not be in a manufactured dairy product in the United States at a level in excess of that from milk with .1 ng aflatoxin M1/ml.

[Introduction in mycotoxin problems (author's transl)]

In Part I the occurrence of mycotoxins is discussed in general terms with emphasis on how they originate in the food, taking full account of presence as secondary contaminants. Further discussions emphasize the occurrence of aflatoxin in foods with a detailed table containing 106 references. Finally, the discussion goes into the factors which influence the formation of mycotoxins and the consequences for the consumer. Part II is concerned with problems in sampling foods with aflatoxin. Difficulties in sampling arise from the different levels of aflatoxins present and from their instability in foods. Based on proposals of different investigators, sample quantities of more than 1 kg are recommended. Regulatory agencies expect concrete plans for statistical evaluation similar to those used for determination of salmonellae. It is particularly important that a solution should be found for the sampling of packaged foods so that a fair and reliable control is possible.