Qom University of Medical Sciences Journal

Introduction
The quality of raw milk is vital for the success of dairy industries worldwide. Achieving this quality depends on economic factors. Today, consuming milk and its products in every society is one of the most important indicators of cultural development [1]. Raw milk is rich in easy-to-digest proteins, vitamins A, B1, B2, and B6, pantothenic acid, saturated and unsaturated fatty acids, and multiple salts. However, milk is poor regarding vitamins K and B12 [2]. Milk is a favorable growth environment for various pathogenic microorganisms. The growth and proliferation of pathogenic microorganisms have adverse effects on the taste and other organoleptic characteristics of milk, including smell and color. It even leads to milk spoilage and fatal diseases for its consumers [3]. fungi and molds are among the microorganisms that can contaminate and decrease milk quality.
Aflatoxins consist of a group of approximately 20 related fungal metabolites. They can be found in a wide range of important food items, including grains, nuts, spices, figs, dried fruits, and most importantly, rations and fodder of animals. Aflatoxin M1 (AFM1) is the hydroxylated metabolite of aflatoxin B1 (AFB1) and is found in milk and subsequently in other dairy products when lactating animals are fed contaminated feed. The presence of AFM1 in milk, especially cow's milk, endangers human health due to its importance as a food for adults and children [8]. Aflatoxin can be produced by three Aspergillus species: Aspergillus flavus, A. parasiticus, and A. nomius. They infect plants and plant products [9].
Methods
In total, 180 milk samples were taken from the supply centers of raw milk, traditional milk, and pasteurized milk to the stores in the city, and after sampling, they were taken to the food hygiene laboratory. First, 5 g of the sample was diluted and prepared up to a dilution of 3 and was cultured linearly in an agar plate culture medium at 37°C for 24 hours. The colonies grown on the plate were counted. To find out the excess water in the milk, we measured the freezing point of the milk. A cryoscope measured the freezing point of raw milk, and a thermolacto-densitometer analyzed its specific gravity. If water alone is added to milk, the specific gravity of milk decreases, and due to the decrease in salt and lactose concentration, the freezing point of milk becomes closer to the freezing point of water. In this experiment, an AFM1 ELISA kit (R-Biopharm, Germany) was used to measure aflatoxin M1 in milk. The test was performed according to the kit manufacturer's instructions.
Results
The results of the statistical analysis of the desired taps in terms of water adulteration are shown. Among the samples, there was a significant difference in terms of non-adulteration (P<0.05). Of course, there was no significant difference between the raw and pasteurized milk samples according to the standards for raw and pasteurized milk. The results of the statistical analysis among the 180 milk samples in terms of total microbial load show significant (P<0.05) differences in terms of their safety. Pasteurized and traditional milk samples had the lowest and highest total counts among the samples, respectively. The results of the statistical analysis among the 180 milk samples in terms of having aflatoxin showed a significant difference (P<0.05) between the samples in terms of their safety. Out of 180 samples, pasteurized and raw milk had the lowest and highest amount of aflatoxin, respectively.
Conclusion
Our study samples were safe for consumption regarding AFM1 contamination. Continuous monitoring and evaluation of AFB1 levels in livestock diets and AFM1 in dairy milk is necessary, especially for countries at high risk for AFM1 contamination.
Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the Islamic Azad University, Sharrekord branch, (Code: IR.IAU.QOMREC.1402.005).
Funding
This study was financially supported by Azad Islamic University, Shahrekord branch.
Authors contributions
All authors contributed equally to preparing all parts of the research.
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgements
The authors would like to thank the president of Shahrekord Azad University.