An Evaluation of Toxic Contaminants in Cereals and Dairy Products in the Republic of Yemen

Abstract

In this study, the frequencies of aflatoxin contamination of dairy products, cereals (corn, wheat, rice, millet, sorghum, and oats) and seed oils (soybean and groundnuts) were determined. The existence of aflatoxin in milk and cereals may pose a threat especially to children. Aflatoxin M1 is cytotoxic, as reported by the in vitro results of studies in human hepatocytes, and its acute toxic molecule in many species as its basic compound aflatoxin B1. About 0.3-6.2% of aflatoxin B1 in feedstuffs is converted to AFM1 in milk. In the first section of this study, the survey was performed regarding to the contamination of AFM1 in Yemen. Determination of AFM1 was by High performance liquid chromatography (HPLC) Fluorometer along with immunoaffinity columns. HPLC was used for analysis of AFM1 in addition to ELISA method. In this current study, a total of 818 milk and milk products samples consist of raw milk, reconstituted milk, powder milk, infant milk, yogurt and cheese samples were analyzed to detect aflatoxin M1. The results showed high frequency for AFM1 in all samples, ranging from 62.2% to 100% with exceeding for the maximum tolerable limits accepted by the European Union (0.05 µg/L for milk, 0.250 µg/L for cheese and 0.025 μg/L for infant milk). The results showed that 51.2 %, 38.4 %, 38.8%, 61.5%, 90.3%, 39.2% and 26.4% of cattle milk, liquid milk, powder milk, infant milk, yogurt, commercial cheese and domestic cheese respectively were above the acceptable limits of EC regulation. During the determination of AFM1 contamination in milk samples taken from different areas in Yemen, AFM1 was found in 65.35% (149/228) of the samples analyzed by HPLC and the concentration range of AFM1contamination was between 0.018 and 3.59 µg/L. On the other hand, 75.1 % (160/213) of samples analyzed by ELISA were contaminated with aflatoxin M1. A total of 228 and 213 samples of milk were evaluated for aflatoxin M1 contamination by HPLC and ELISA respectively. The occurrence of AFM1 was determined in raw milk (cattle milk), reconstituted milk (liquid milk), powder milk and infant milk. In our study, a total of 156 cattle milk samples were analyzed to detect AFM1 by HPLC and ELISA. Another study was carried out on 104 samples of yogurt to determine of AFM1 contamination by ELISA and HPLC methods. The total of results showed that all analyzed samples of yogurt were contaminated with AFM1 with ranging from 0.021 to 0.894 μg/L and means ±SE is 0.36±0.029 μg/L. In the present study, the result of AFM1 contamination revealed that 94 (95.19%) of 104 yogurt samples were exceeded the admissible limit of the European Commission (EC) that set at 0.050 µg/kg with ranging between 0.05 and 0.894 µg/kg. Also, a total of 273 cheese samples were analyzed by ELISA and HPLC technique to detect AFM1 contamination. The samples of cheese were collected from supermarkets and retailers and contained commercial cheese and traditional cheese (Taizi cheese). A 216 (79.12%) of the 273 cheese sample were contaminated with AFM1 with ranged from 0.020-5.955 μg/Kg and the means ± was 0.40±0.066 μg/Kg. The contamination of commercial and traditional cheese with AFM1 was 84.67% (116/273) and 73.53% (100/273) respectively. There is no significant difference between the results of aflatoxin M1 in the samples of commercial or traditional cheese, whether on the basis of the test method or depending on the type of cheese. In this study, 89 (32.6%) of 273 cheese samples were contaminated with AFM1 in level above the acceptable limit of the European Commission (EC) that set as 0.250 μg/Kg. There is lower percentage of AFM1 contamination in the cheese samples as compared to yogurt samples. On the other hand, 68 real samples of raw milk (cattle milk) and 78 traditional cheeses which were obtained from different retailers and donators in Yemen, were analyzed for AFM1 to compare ELISA and HPLC method. In this comparative study, cattle milk showed that 62(79.49%) and 56(71.79%) of 78 cattle samples were AFM1 contamination by ELISA and HPLC respectively. While, traditional cheese samples were showed 76.47% and 71.79% of samples contaminated with AFM1 by ELISA and HPLC respectively. From the results of cattle milk and traditional cheese samples, we can confirm that the percentage of AFM1 contamination by ELISA and HPLC were corresponded and there were no significant differences noted. This study revealed that the presence of AFM1 contamination in different types of milk and milk products. Therefore, all dairy products have to be controlled durably to keep contamination of AFM1 under the permissible limit. Essential preservation will have to be taken to reduce the AFM1 contamination in dairy products. This work is considered as a first data on AFM1 in Yemen, so the conclusion of this study aims to produce awareness in the public about the hazards of AFM1. Since the AFM1 considered a significant risk, so milk and milk products must be monitoring by the public health authorities through setting the standard regulation and specification and by inspection and surveillance on the milk, milk product and feedstuffs in regard to AFM1 and other aflatoxins. In the second phase of this project, a total of 744 samples of cereals including169 corn, 230 wheats, 157 rice, 69 sorghums, 75 millet and 44 oat samples were analyzed to determine total aflatoxins. The samples were collected from different districts (Sanaa, Al-Hodaydah and Aden) in Yemen. The contamination of corn, wheat, millet, rice, sorghum and oats with total aflatoxin were 65.7 %, 93.9%, 62.6%, 87.3%, 76.8% and 81.8 respectively. Also, Total aflatoxin was conducted on groundnuts and soybean samples by ELISA and the results revealed that 85.4% and 72.3 of groundnuts and soybeans samples were contaminated with total aflatoxins (B1, B2, G1, and G2) respectively. This research determined the contamination of cereals, soybean and groundnuts with total aflatoxins by ELISA method. In our study, we used samples marketed in Yemen which were collected from Sana`a, Al-hodayda and Aden. We have shown through this study that these foodstuffs are contaminated with total aflatoxins (B1, B2, G1, and G2) with different concentrations. In addition, the contamination of these cereals and oilseeds with total aflatoxins (B1, B2, G1, and G2) were greater than limits set by the European Union (4 µg/Kg), whereas most of samples were in the safe levels according to the limits set by Yemen/FAD regulation (20 µg/Kg). The present results demonstrated that high level of contamination with aflatoxin across the study areas exists. So precautions must be taken during all times of crops storage (low temperature, Low moisture content, and low humidity conditions) because these depress the fungus growth and thus eliminate incidence of aflatoxin contamination. The results of this work suggest that safety limits for aflatoxin are needed for controlling, regulating and ensuring the quality of these commodities. Aflatoxin is considered a real hazard to human health and serious risk to the consumers. Therefore, stringent measures should be taken by Health and Food Safety Authorities through standard regulations and specifications; by inspection and surveillance on foodstuffs and feedstuffs in regard to AFM1 and other aflatoxins.