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Raw milk can be a source of dangerous microorganisms that pose serious health risks. Several foodborne illness outbreaks in the Pacific Northwest and elsewhere in the U.S. have been traced to drinking raw milk.
Home pasteurization is a good safeguard against possible risk of illness. The heat of pasteurization kills harmful bacteria such as Salmonella, Listeria, and E. coli O157:H7. These disease-causing bacteria can even be in raw milk that is produced with good sanitation practices.
It’s especially important to pasteurize raw milk that will be consumed by people who are susceptible to foodborne illness. That includes pregnant women, young children, older adults, and those with cancer, HIV/AIDS, and other immune system compromised diseases.
Methods of pasteurization
Stove top
For best quality, raw milk must be heated slowly during pasteurization. Use a double boiler or place a small saucepan inside a large pan or slow cooker.
- Put water in the bottom pan and bring it to boiling.
- Pour the raw milk into the top pan. Heat it over the boiling water, stirring constantly.
- Use a cooking thermometer to determine when the temperature reaches 161° F. and keep it at this temperature for 15 seconds.
- Set the pan of hot milk in a container of cold water. Keep the water cold by adding ice.
- Continue to stir until the milk is cold, then store in the refrigerator.
Lower temperature method
Heat raw milk to 145°F and hold at that temperature for 30 minutes.
- Follow steps above for stove top pasteurization.
- Place a cooking thermometer into the milk to measure its temperature.
- Bring the temperature to 145°F. Keep the milk at or above this temperature for 30 minutes, stirring frequently. Hold the temperature steady.
- Remove from heat cool as directed above.
Caution: Temperatures under 145°F will not kill harmful bacteria. If the temperature drops below 145°F at any time during heating, raise the temperature and restart the timer for 30 minutes.
Microwave
Raw milk can also be pasteurized in a microwave oven.
- Place milk in a microwave safe glass container.
- Heat to 161°F. for 15 seconds using a thermometer or temperature probe.
- Stir the milk once or twice during the heating period to equalize the temperature throughout.
- Set the pan of hot milk in a container of cold water. Keep the water cold by adding ice.
- Continue to stir until the milk is cold, then store in the refrigerator.
Electric home pasteurizer
Electrically operated, batch-type home pasteurizers are available that automatically control the pasteurization time and temperature and pasteurize from around two to twelve gallons of milk. Such units make it possible to easily pasteurize milk with minimum attention. Some of these units can even be attached to your sink and will automatically cool the milk using water.
Note: Pasteurization doesn’t destroy the nutritional value of milk. The milk is still an excellent source of calcium as well as protein.
