1. Safety of dairy products
Dr. A.M. Mortazavian

2. Introduction
Milk and milk products are indispensable components of the food supply chain
Dairy products are consumed by all population groups
Possible contamination by either a microbiological, chemical or physical hazard would affect a large population.

3. Food safety hazards in dairy products
Physical
Biological
Chemical

4. Physical hazards
Consist of detectable pieces of non-food material (foreign bodies) such as glass, wood, metal pest, plastic
which have found their way into food from:
machinery
environment
packaging
personnel

5. Microbial hazards
Microbial hazards pose the greatest immediate food safety threat to the consumer and enter milk via:
Unhealthy animal
People hands
Milking utensils
Water
Production area (GHP)
Ingredients and additives
Packaging and packs

6. Microbial hazards Bacteria Virus Fungi Protozoa
Types of microbiological hazards in milk and dairy products:
Bacteria
Virus
Fungi
Protozoa

7. Bacterial hazards
Various bacteria of public health concern found in milk and dairy products include:
M. tuberculosis
Brucella melitancis
Salmonella spp.
Listeria monocytogenes
Campylobacter jejuni
Yersinia enterocolitica
Pathogenic strains of Escherichia coli
Enterotoxigenic strains of Staphylococcus aureus

8. Protozoan parasites Viral hazards Cryptosporidium parvum
Entamoeba histolytica
Giardia lamblia
Toxoplasma gondii
Viral hazards
Enteroviruses, including polioviruses and Coxsackie virus, Rotaviruses
Foot and mouth disease virus
Hepatitis virus

9. Antibiotic drugs Tetracyclines Beta-lactams Amino glycosides.
penicillins , cephalosporins
Beta-lactams
Oxytetracycline, tetracycline and chlortetracyclin
Tetracyclines
streptomycine, neomycin and gentamycin
Amino glycosides
Erythromycin
Macrolides
Sulfamethazines
Sulfonamides

10. Concerns linked to use of antimicrobials
Potential development of antibiotic-resistant pathogens, which may then complicate human
treatment.
sensitive individuals may exhibit allergic reactions to residues of antibiotics and/or their
metabolites, as mainly seen with B-lactam antibiotics

11. Chemical hazards
Dairy processing
Packaging
Dairy additives
indigenous

12. Pesticides and insecticides
Contamination of feeds arises in the field or store where treatment with pesticides occurs.
The common pesticides presented below can enter milk and dairy products.
Chlorinated pesticides and related compounds like DDT
Organophosphates insecticide

13. Consumption of these compounds could lead to cancers such as breast cancer.
OC pesticides are fat soluble, so can be found predominantly in high-fat dairy products such as cream and butter.
Heat treatment of milk and the activity of the starter bacteria in yogurt can decrease its amount.
Most of the developed countries have established maximum residue levels (MRLs) of pesticides in milk and milk products.

14. Hormone residue Steroid hormones
The amounts of lipophilic hormones (progestrone and estrogen) depend on the fat content of the milk and dairy products.
Food processing does not seem to influence the amount and ratios of the hormones but cheese ripening does.
Probably not only propionic acid bacteria but also other fermenting bacteria or clotting enzymes are responsible for the formation of testosterone during the fermentation process.

15. Bovine growth hormone (BGH)
BGH increases activity and/or longevity of mammary secretary cells, probably via Insulin-like Growth
Factor (IGF)-I produced by the liver and/or the mammary gland.
Raw milk and pasteurized milk could have levels of IGF-I of 5.6 and 8.2 ng mL-1, respectively.
Dairy products that contain hormones (such as IGF-I) could increase breast
cancer risk.

16. Parasiticide drugs
Albendazole is a widely used benzimidazole anthelmentic. Residues of benzimidazole compounds such as
albendazole sulfoxide,
albendazole sulfone and
albendazole 2-amino sulfone
can occur in milk and dairy products and it is necessary to observe withdrawal periods for milk
after therapy

17. Dioxine & Polychlorinated biphenyls
The known toxic effects of dioxin include Dermal toxicity, Immunotoxicity, Reproductive abnormalities Endocrine disruption Carcinogenicity Dairy products contribute about 1/4 to 1/2 to the dietary intake of total dioxins.

18. Heavy metals
Elements such as chromium and nickel enter from direct contact with stainless steel dairy equipment.
Heavy metals such as cadmium, lead, mercury, and arsenic are not expected to have any direct contact
with milk .
They enter milk through the ingestion of contaminated feed and water by milk-producing animals. Pb As Cr Cd Cu Zn

19. Heavy metals produce toxic effects by replacing essential metal ions existing in the chelates present in body
Even in low-level, exposure to inorganic arsenic is related to increased risk of cancer in lung
skin,
bladder
Also, developmental arsenic exposure may lead to increases in pancreatic and hematopoietic cancer .

20. Comparison of heavy metal concentrations in milk samples of different countries

21. The most important mycotoxins present in dairy products include:
Aflatoxin M1
Ochratoxin
Trichotecenes
Zearalenone
Fumonisin

22. Aflatoxins are toxic, carcinogenic, and/or teratogenic to humans and animals.
The International Agency for Research on Cancer (1994) classified AFB1 as a class 1 human carcinogen and AFM1 as a class 2B possible human carcinogen
AFM1 is relatively stable in raw and processed milk products and is not destroyed by regular heat
treatments including pasteurization.
AFM1 has chronic and acute effects on human health.

23. Melamine
Transfer of melamine from melamine-containing feed to cow’s milk has been reported.
Furthermore, melamine is a minor metabolite of the pesticide cyromazine and is also used in some
fertilizers.
The primary target for the toxic action of melamine is the kidneys and the urinary tract.
Levels of melamine reported in dairy products ranged from 0.09 to 6200 mg/kg

24. Processed- produced compounds in dairy products
Two important factors (such as proteins, fats, carbohydrates, and vitamins) can generate carcinogenic and mutagenic compounds from dairy ingredients : ) sever heating
2) exposure to sunlight
Reactions intensified by high temperature :
Pyrolysis and decomposition
fat oxidation
Maillard reactions

25. Fat auto-oxidation and photo-oxidation in high- fat dairy products
Free radicals
Polymerized compounds
Induction of Cancer

26. Maillard reaction
The Maillard reaction has considerable consequences on the quality of heated milk and milk products in
terms of color,
flavor
nutritional value
probable toxic compounds
Nutritional loss (Lys, Pro, lactose, fat)/Schiff base is digestible but become indigestible after Amadori rearrangement due to
crosslinking of lactose with Pro, so tripsin can not affects it.
Millard products are act as chelating agents especially for ‘Fe’.
Some of its products might be toxic and/or mutagenic

27. Crosslinking in proteins
dehydroalanine
β - elimination
Ser
Cys
heat
+ Lys
+ cys
lanthionine
lysinoalanine

28. Cholesterol oxidation products (COPs)
COPs level in milk and dairy products is very small.
Formation of COPs in dairy products can only occur under harsh conditions :
application of high heating temperatures for a long period
long storage at high temperatures,
in the case of foods in the dehydrated state or at low water activities.
COPs have many biological effects such as teratogenic, cytotoxic, mutagenic

29. Malignant tumors Asthma
Dairy Additives
Additives such as flavors, colors, sweeteners, antioxidants, and antimicrobial preservatives could possess
toxic side effects when exceeding their respective permitted dose of consumption per day.
Brilliant blue FCF, used as a coloring agent, can induce
Cancer
Malignant tumors Asthma
Hyperactivity

30. Carageenan as a thickening agent Long- term administration cause
Flavored dairy products that contain sucrose
Intestine mucous membrane damage or ulcerous colonitis,
produce or promote tumor growth
Increase the risk of colorectal cancer
insulin resistance
pancreatic cancer

31. Sweeteners such as saccharin and aspartame have been reported to be carcinogenic agent and induce bladder cancer.
Chemical additives such as sodium carbonate and sodium bicarbonate added to milk as neutralizers to preserve it for longer time and to prevent curdling may cause health hazards to the society

32. Groups of analytes monitored in milk-PNCRC, 2012

33. Programs for hazards prevention and control in dairy industry
HACCP Program
Total Quality Management Quality Assurance

34. Foundation of HACCP -Prerequisite Programs

35. An example of possible hazards, control and orientation of yoghurt production

36. An example of possible hazards, control and orientation of ice-cream production