Evaluation of Aflatoxin M1 Residues in Traditional Iranian Cheese (Koupeh Cheese) samples by ELISA

Abstract

Background and Objectives: Local cheese made from raw milk is one of the most commonly consumed dairy products in the world. Mycotoxin contamination of foodstuff and its transmission to consumers are extremely important public health issues. The purpose of this survey was to determine the level of aflatoxin M1 (AFM1) residues in Koupeh cheese, a traditional fermented Iranian cheese produced in spring and summer.Methods: We randomly collected 48 local cheese samples produced in Mahabad (northwest of Iran) during spring and summer. The level of AFM1 was measured by enzymelinked immunosorbant assay using commercial kits and a microplate reader.Results: All samples contained measurable amounts of AFM1. Cow milk cheese samples contained higher level of AFM1 compared to sheep milk cheese samples. The level of AFM1 in the samples from both animals was lower in summer. There was no significant difference between the mean level of AFM1 in summer and spring. Moreover, 33.3% of cow milk cheese samples collected in spring and 16.6% of the samples collected in summer contained toxin levels higher than the maximum allowed concentration set by the European Commission (250 ng/Kg) and by the Institute of Standards and Industrial Research of Iran (200 ng/Kg). Conclusion:The results of this study show that the level of AFM1in Koupeh cheese is influenced by the livestock type and production season, in a way that the level of contamination is higher in spring.Keywords: Cheese, Cultured Milk Products, Aflatoxin M1, ELISA. MATERIAL AND METHODSThis observational and cross sectional study was performed on 48 randomly collected traditional cheese samples from the city of Mahabad (Iran) during spring and summer. The samples (100g each) were kept in freezer at -18 °C. Presence of AFM1 in the samples was evaluated by enzyme-linked immunosorbent assay (ELISA). ELISA kits (sensitivity of 5 ng/L) used in this study were purchased from R-Biopharm Inc., Germany. In this test, cross-reaction with AFM1 was 100% and no cross-reactivity was observed with AFB1, B2, G1 and G2. Moreover, the aflatoxin recycling rate has been reported to be 95% with 15% error rate. First, the samples were thawed and placed in the bottom of a refrigerator for 12 hours before the test. After homogenization, 2g of each cheese sample were weighed accurately and then added to a 50 ml balloon containing 40 ml of dichloromethane. The contents were stirred for 15 minutes and the suspension was filtered using syringe filters. Then, 10 ml of the filtrate was evaporated at 60 °C and the sediment was dissolved in a mixture of 0.5 ml methanol with 0.5 ml phosphate buffer and 1 ml heptane. The mixture was centrifuged at 2700 RPM for 15 minutes at 10°C. Supernatant (heptane layer) was removed completely and 100 μl of subphase (methanol layer) was diluted with 400 μl of phosphate buffer. Later, 100 μl of standard solution and the prepared cheese samples were added to a microplate. After placing the microplate at 20-25 °C for an hour, the content of the microplate was removed a...

A national systematic literature review for aflatoxin M1 in commonly consumed cheese brands in Iran: Human health risk assessment by Monte Carlo simulation

“…The effects of aflatoxins on humans are indirectly experienced by consuming animal products, especially dairy products such as cheese [ 8 , 13 ]. Research has indicated that the existence of AFM1 in milk and dairy products presents a considerable risk to public health, particularly in communities where dairy consumption is a prominent component of their daily nutritional intake [ 14 , 15 ]. Sterilization, pasteurization, preparation, and storage techniques in the dairy industry and milk processing for cheese production fail to impact the reduction of toxicity and survival of AFM1 significantly.…”