2. Instructor Notes
Your responsibility for serving safe food in your establishment starts long before you serve meals.
Many things can happen to a product on its path through the establishment, from purchasing and receiving, through storing, preparing, cooking, holding, cooling, reheating, and serving—known as the flow of food.
The safety of the food you serve will depend largely on your understanding of food safety concepts throughout the flow of food, especially the prevention of cross-contamination and time and temperature control. It also depends upon your ability to develop a system that prioritizes, monitors, and verifies the most important food safety practices.
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3. Create physical barriers between food products
Physical barriers include:
Assigning specific equipment to each type of food
Cleaning and sanitizing work surfaces, equipment, and utensils after each task
Instructor Notes
A major hazard to food as it flows through your operation is cross contamination. Prevention starts with the creation of barriers between food products.
Cross-contamination can be prevented by placing physical barriers between products, including:
Assigning specific equipment to each type of food product. For example, use one set of cutting boards, utensils, and containers for poultry and another set for meat. Some manufacturers make colored cutting boards and utensils with colored handles. Color-coding can tell employees which equipment to use with what products.
Cleaning and sanitizing all work surfaces, equipment, and utensils after each task. For example, after cutting up raw chicken on a cutting board, be sure to wash, rinse, and sanitize it or run it through a warewashing machine.
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4. Create procedural barriers between food products
Procedural barriers include:
Preparing raw and ready-to-eat food at different times when using the same prep table
Purchasing ingredients that require minimal preparation
Instructor Notes
Cross-contamination can be prevented by placing procedural barriers in your operation, including:
Preparing raw and ready-to-eat food at different times when using the same prep table. For example, establishments with limited prep space can prepare lunch salads in the morning, clean and sanitize the utensils and surfaces, and then debone chicken for diner entrées in the same space in the afternoon.
Purchasing ingredients that require minimal preparation. For example, an establishment can switch from buying raw chicken breasts to purchasing pre-cooked breasts.
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5. To prevent time-temperature abuse:
Cook, hold, cool, and reheat food properly
Discard food that spends longer than four hours in the TDZ
Build time-temperature controls into recipes
Make calibrated thermometers available
Remove only as much food from storage as necessary
Instructor Notes
One of the biggest factors in foodborne-illness outbreaks is time-temperature abuse. Disease-causing microorganisms grow and multiply at temperatures between 41F and 135F (5C and 57C), which is why this range is called the temperature danger zone (TDZ).
At temperatures between 70F and 125F (21C and 52C), microorganisms grow faster than at any point.
Microorganisms also need time to grow. The longer food stays in the TDZ, the more time microorganisms have to multiply and make food unsafe. It is recommended that food does not remain in the zone for more than four hours.
Building time-temperature controls into recipes may include refrigerating ingredients prior to preparation and cooking food to its required minimum internal temperature.
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6. Photos courtesy of Cooper-Atkins Corporation
Common Types of Thermometers
Instructor Notes
To manage time and temperature, you need to monitor and control them. The thermometer may be the single most important tool you have to protect your food.
Bimetallic Stemmed Thermometer
Thermocouple
Infrared Thermometer
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Photos courtesy of Cooper-Atkins Corporation

7. Bimetallic Stemmed Thermometer
Instructor Notes
The bimetallic stemmed thermometer is the most common and versatile type of thermometer. It should have an adjustable calibration nut and a dimple to mark the end of the sensing area (which begins at the tip).
When checking the internal temperature of food using a bimetallic stemmed thermometer, insert the stem into the product so that it is at least immersed from the tip to the end of the sensing area.
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8. Photos courtesy of Cooper-Atkins Corporation
Thermocouples and Thermistors
Measure temperature through a metal probe or sensing area
Display results on a digital readout
Come with interchangeable probes
Instructor Notes
Immersion probes are used to measure the temperature of liquids.
Surface probes are used to measure the temperature of flat cooking equipment.
Penetration probes are used to measure the internal temperature of food. Small-diameter probes should be used to measure the internal temperature of thin food, such as meat patties and fish fillets.
Air probes are used to measure the temperature inside refrigerators or ovens.
Immersion Probe
Surface Probe
Penetration Probe
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Photos courtesy of Cooper-Atkins Corporation

9. Photo courtesy of Cooper-Atkins Corporation
Infrared Thermometers
Used to measure surface temperature of food/equipment
Must be held as close to product as possible
Remove barriers between thermometer and product
Follow manufacturer’s guidelines
Instructor Notes
These thermometers are not designed to measure air temperature or the internal temperature of food.
Do not take temperature measurements through glass or shiny or polished metal surfaces, such as stainless steel or aluminum.
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Photo courtesy of Cooper-Atkins Corporation

10. Time-Temperature Indicators (TTIs)
Self-adhesive tags or sticks attached to food shipments
Provides irreversible record when product’s temperature has exceeded safe limits during shipment or storage
Instructor Notes
If temperature limits are exceeded during shipment or storage, the TTI produces an irreversible record, often in the form of some type of color change.
More suppliers are using recording devices in their delivery trucks to continuously monitor temperatures. These devices can be checked to see if the temperature inside a truck changed at any time during transit.
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11. Which temperature-measuring device should be used to check the
___ 1. internal temperature of a hamburger patty?
___ 2. surface temperature of a steak?
___ 3. temperature of chicken during transport?
___ 4. internal temperature of a roast?
___ 5. internal temperature of a large stockpot of soup?
B. Thermocouple
Instructor Notes
Answers: B A D
B or C
C. Bimetallic stemmed
thermometer
D. Time-temperature indicator
A. Infrared thermometer
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12. When using thermometers:
Clean and sanitize them between uses
Calibrate them regularly
Insert the thermometer stem or probe into thickest part of product
Wait for reading to steady before recording temperature
Never use mercury or spirit-filled glass thermometers to check food temperature
Instructor Notes
Thermometers should be washed, rinsed, sanitized, and air-dried before and after each use to prevent cross-contamination.
Thermometers should be calibrated before each shift or before each day’s deliveries. They should be recalibrated if they have been dropped, or after they have experienced a severe temperature change.
When checking the temperature of food, it is a good practice to take at least two readings in different locations, since product temperature may vary across the food portion.
When checking the internal temperature of food using a bimetallic stemmed thermometer, insert the stem into the product so that it is at least immersed from the tip to the end of the sensing area. When measuring the internal temperature of thin food, such as meat or fish patties, small diameter probes should be used.
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13. Ice-Point Method Instructor Notes
Calibration is the process of ensuring that a thermometer gives an accurate reading by adjusting it to a known standard, such as the freezing point or boiling point of water.
There are two acceptable methods of calibration. They are the ice-point method (the most often used) and the boiling-point method.
Follow these steps when using the ice-point method to calibrate a thermometer:
Step 1:
Fill a large container with crushed ice. Add clean tap water until the container is full, and then stir the mixture well.
Step 2:
Put the thermometer stem or probe into the ice water so the sensing area is completely submerged. Wait thirty seconds, or until the indicator stops moving. Do not let the stem or probe touch the container’s bottom or sides. The thermometer stem or probe must remain in the ice water.
Step 3:
Hold the calibration nut securely with a wrench or other tool and rotate the head of the thermometer until it reads 32F (0C). On some thermocouples or thermistors, it may be possible to press a reset button to adjust the readout. Hold the calibration nut securely with a wrench or other tool and rotate the head of the thermometer until it reads 32F (0C). On some thermocouples or thermistors, it may be possible to press a reset button to adjust the readout.
Step 1
Step 2
Step 3
Fill container with crushed ice and water
Submerge sensing area of stem or probe for 30 seconds
Hold calibration nut and rotate thermometer head until it reads 32˚F (0˚C))
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14. Boiling-Point Method Step 1: Bring a deep pan of water to a boil
Step 2: Submerge sensing area of stem or probe for 30 seconds
Step 3: Hold calibration nut and rotate thermometer head until it reads 212F (100C)
Instructor Notes
Follow these steps when using the boiling-point method to calibrate a thermometer:
Step 1:
Bring clean tap water to a boil in a deep pan.
Step 2:
Put the thermometer stem or probe into the boiling water so the sensing area is completely submerged. Wait thirty seconds, or until the indicator stops moving. Do not let the stem or probe touch the pan's bottom or sides. The thermometer stem or probe must remain in the boiling water.
Step 3:
Hold the calibration nut securely with a wrench or other tool and rotate the head of the thermometer until it reads 212F (100C). (The boiling point of water is about 1F (about 0.5C) lower for every 550 feet (168m) you are above sea level.) On some thermocouples or thermistors, it may be possible to press a reset button to adjust the readout.
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15. Put the steps for calibrating a bimetallic stemmed thermometer in order
___ A. Rotate the head of the thermometer until it reads 32F (0C).
___ B. Submerge the sensing area of the thermometer stem or probe, and wait for the reading to steady.
___ C. Fill a container with crushed ice and clean tap water.
___ D. Hold the adjusting nut with a wrench or other tool.
Instructor Notes
Answers: 4 2 1 3
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