Microbiology and Deterioration of Milk and Milk Products

Pathogenic Microorganisms in Milk

• Pathogenic Microorganisms in Milk
• Food borne illnesses occur as a result of :
• ~Ingestion of raw milk
• ~Improper pasteurization
• ~Poor handling / storage leading to PP contamination
• Measures to decrease the threat :
• ~Hygienic production practices
• ~Proper handling and storage
• ~Pasteurization

Microbial Pathogens

• Microbial Pathogens
• Bacillus cereus
• Listeria monocytogens
• Yersinea entrocolitica
• Salmonella spp.
• E.coli O 157:H7
• Compylobacter jejuni
• Coxeilla burnetii
• Moulds (Aspergillus, Fusarium, Penicillium) grow in milk and milk products & produce potentially hazardous mycotoxins.

Control and Practical Application

• Control and Practical Application
• Heat - pasteurization , sterilization etc.
• Ionizing Radiations- UV., gamma rays
• High frequency sound waves- super & ultrasonic
• Electricity - by the heat generated.
• Pressure - 600 x > atmospheric pressure
• Chemicals Acids ,alkalis, halogens H202 etc.

Pasteurization of milk

• LTLT : Low temp. Long time 63°C 30 minutes
• HTST: High temp. Short time72°C 15 seconds
• UHT : Ultra high temp.,130-135 °C 1 second
• Pasteurization:
• Kills and removes all pathogens(100%)
• Kills most non pathogens (99%)
• Surviving organisms are spore formers, thermoduric and thermophilic organisms

Pasteurization of milk

• • Common thermoduric organisms:
• Bacillus, Micrococci, Lactococci, Arthrobacter
• Microbacteria, Corynebacteria
• Pasteurization provide a product with average shelf life 7-10 days( LTLT-HTST)
• Types and numbers of bacteria in milk depend on the microbial load before pasteurization