Bacterial contamination of raw milk: Sources and factors

The dairy products industry is going toward safe milk and its products in the food market. Milk quality and food safety concern in the consumers’ health and nutrition in public health surveillance prevent food-borne diseases, food poisoning, and zoonosis risk by raw milk and fresh dairy products. The consumption of pathogen containing products may cause illnesses ranging from upset stomach to more serious symptoms (e.g., diarrhea, fever, vomiting, and so on.

Researches showed that, the number and types of microorganisms in milk immediately after milking are affected from different factors which include:
*poor hygienic condition of the milking environment,
*absence of cooling system,
*poor sanitary condition of the milk containers,
*poor udder and teats cleaning practice,
*failure of washing and drying cow’s udder,
*the absence of usage of detergent for cleaning vending environments, and
*the poor personal hygiene of the milkers.

Additionally, condition of storage, manner of transport, use of plastic containers for milk collection, mixing of milk obtained from different cows and the presence of further contamination at the milk selling sites.

Raw milk can often be contaminated with pathogens, either directly through organisms shed as a result of udder infection or indirectly. Indirect contamination may arise from:
*a cow’s own faecal matter contaminating the udder and teats,
*faecal matter of other cows contaminating the udder
*milking clusters contacting surfaces with faecal contamination, and
*post-harvest environmental contamination.

Bacterial contamination of raw milk can originate from distinct or different sources: air, milking system, feed, soil and, skin or hair of the animals or utensils.

Once it is secreted from the udder, milk can easily be contaminated by spoilage microorganisms and food-borne pathogens from various sources including animal faeces, soil, air, feed, water, equipment, animal hides and people. Thus, the prevalence of pathogenic and spoilage microorganisms in milk and dairy products is influenced by a high number of factors and their combinations.

The mammary gland participates in the excretion of numerous xenobiotic substances from veterinary drug milk residues and contaminants originated from milk and other chemical residues to environmental pollutants on the grasslands, animal feedstuffs, and the field crops. The presence of residual concentrations of milk contaminants and pathogens is an indicator of milk quality in cow dairy farms.
Bacterial contamination of raw milk: Sources and factors