1. The Flow of Food: An Introduction

2. Apply Your Knowledge: Test Your Food Safety Knowledge
True or False: Chicken held at an internal temperature of 125°F (52°C) has been temperature abused
True or False: Infrared thermometers are best for measuring the internal temperature of food
True or False: When checking the temperature of a roast using a bimetallic stemmed thermometer, only the tip of the thermometer stem should be inserted into the product
True or False: A thermometer calibrated by the boiling- point method must be set to 135°F (57°C), after being placed into the boiling water
True or False: Washing and rinsing a cutting board will prevent it from cross-contaminating the next product placed on it
Instructor Notes
Answers:
True
False
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3. The Flow of Food To keep food safe: Prevent cross-contamination
Prevent time-temperature abuse
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.

4. Preventing Cross-Contamination
Create physical barriers between food products:
Assign specific equipment to each type of food
Clean and sanitize 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 dishwashing machine.

5. Preventing Cross-Contamination
Create procedural barriers between food products:
Prepare raw meat, fish, and poultry and ready-to-eat food at different times (when using the same prep table)
Purchase ingredients that require minimal preparation
Instructor Notes
Cross-contamination can be prevented by creating procedural barriers between products, 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 dinner 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 precooked frozen breasts.

6. Preventing Time-Temperature Abuse
This includes:
Minimizing the time food spends in the temperature danger zone
Determining the best way to monitor time and temperature
Making thermometers available
Regularly recording temperatures and the times they are taken
The Temperature Danger Zone
Microorganisms grow rapidly
Microorganisms survive and grow
Instructor Notes
Foodborne microorganisms grow at temperatures between 41F and 135F (5C and 57C), which is why this range is known as the temperature danger zone (TDZ). They grow much faster at temperatures between 70F and 125F (21C and 52C).
Microorganisms also need time to grow. To keep food safe, you must minimize the amount of time it spends in the TDZ. If food is held in this dangerous range for four or more hours, you must throw it out.
Determine which food items should be monitored, how often, and by whom. Give employees their own calibrated thermometers. Print simple forms they can use to record time and temperatures throughout the shift.

7. Temperature-Measuring Devices
Bimetallic Stemmed Thermometer
Indicator Head
Calibration Nut
Holding Clip
Stem
Instructor Notes
Bimetallic stemmed thermometers measure temperatures through a metal probe with a sensor toward the end.
They should have an adjustable calibration nut to keep them accurate, and a dimple to mark the end of the sensing area (which begins at the tip). They should also be accurate to +/- 2ºF (+/- 1ºC).
When checking the temperature of food using a bimetallic stemmed thermometer, insert the stem into the product so that it is immersed from the tip to the end of the sensing area.
Sensing Area
Dimple

8. Temperature-Measuring Devices
Thermocouples and Thermistors
Measure temperature through a metal probe or sensing area
Display results on a digital readout
Often come with interchangeable probes
Instructor Notes
Immersion probes are used to measure the temperature of liquids such as soups, sauces, or frying oil.
Surface probes are used to measure the temperature of flat cooking equipment like griddles.
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
Photos courtesy of Cooper-Atkins Corporation

9. Temperature-Measuring Devices
Infrared Thermometers
Used to measure the surface temperature of food and equipment
Must be held as close to the product as possible
Remove barriers between thermometer and product
Follow manufacturers’ guidelines
Instructor Notes
These thermometers are not designed to measure air temperature or the internal temperature of food.
Hold the thermometer as close as possible to the product without touching it. Do not take temperature measurements through glass or shiny or polished- metal surfaces, such as stainless steel or aluminum.
Always follow the manufacturers’ guidelines. They can provide tips on obtaining the most accurate temperature reading.
Photos courtesy of Cooper-Atkins Corporation

10. Apply Your Knowledge: Pick the Right Thermometer
Which temperature-measuring device should be used to check the following?
Internal temperature of a hamburger patty
Surface temperature of a steak
Internal temperature of a roast
Internal temperature of a large stockpot of soup 1 2 3 4
B. Thermocouple
C. Bimetallic stemmed
thermometer
Instructor Notes
Answers: B A
B and C
A. Infrared thermometer
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11. Calibrating Thermometers
Calibration
Adjusting a thermometer in order to get an accurate reading
Two methods
Boiling-point method
Ice-point method
Instructor Notes
Thermometers can be calibrated by adjusting them to the temperature at which water boils—the boiling point, or the temperature at which water turns to ice—the ice point.
While either method can be used, the ice-point method is more common.

12. Calibrating Thermometers
Boiling-Point Method
Bring clean tap water to a boil
Submerge the sensing area of the thermometer stem or probe in the water for thirty seconds
Hold the calibration nut and rotate the thermometer head until it reads 212°F (100°C)
Note: The boiling point of water varies depending upon your elevation 1 2 3
Instructor Notes
Follow these steps when using the boiling-point method to calibrate a thermometer:
1: Bring clean tap water to a boil in a deep pan.
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 bottom or sides of the pan. The thermometer stem or probe must remain in the boiling water.
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.

13. Calibrating Thermometers
Ice-Point Method
1. Fill a large container with crushed ice and water
2. Submerge the thermometer stem or probe in the water for thirty seconds
3. Hold the calibration nut and rotate the thermometer head until it reads 32˚F (0˚C)
Instructor Notes
Follow these steps when using the ice-point method to calibrate a thermometer:
1: Fill a large container with crushed ice. Add clean tap water until the container is full, and then stir the mixture well.
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.
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.

14. General Thermometer Guidelines
When using thermometers:
Keep thermometers and their storage cases clean
Calibrate them regularly to ensure accuracy
Never use glass thermometers to monitor food temperature
Insert the thermometer stem or probe into thickest part of product (usually the center)
Wait for the thermometer reading to steady before recording the temperature of a food item
Instructor Notes
Thermometers should be washed, rinsed, sanitized, and air-dried before and after each use to prevent cross-contamination. Use an approved food-contact surface sanitizing solution to sanitize them.
To ensure accuracy, 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.
Glass thermometers should not be used since they can pose a serious danger to employees and customers if they break.
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 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.
Wait at least fifteen seconds from the time the thermometer stem or probe is inserted into the food.
Remind participants that the Take It Back section in ServSafe Essentials (page 5-18) can be used to teach important concepts from Section 5 to their employees.

15. Apply Your Knowledge: Calibrate the Thermometer
Put the steps for calibrating a thermometer in the proper 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 A B C D
Instructor Notes
Answers: 4 2 1 3
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