What type of thermometer probe should be used to check the internal temperature of a beef roast?

Ensuring foods are cooked and reheated to the correct temperature is a critical component of food safety. If food is not cooked correctly, dangerous pathogens could grow and result in a foodborne illness. Not only does this endanger your valued guests, but a foodborne illness could be costly to your business, resulting in loss of trust and reputation, negative media exposure, lawsuits and legal fees, decreased staff morale, increased insurance premiums and more. To prevent this, it’s important to understand what the minimum internal cooking temperatures for each food type are and how to properly check temperatures.

This is part of our ongoing Food Safety 101 series. Check out our Crash Course in Food Safety here.

Making sure food reaches its minimum internal cooking temperature and that they stay there for the proper amount of time is the best way to reduce pathogens to safe levels for consumption. What are the minimum internal cooking temperatures? This varies from product to product. The following temperatures and times have been developed for foods needing Time and Temperature Control for Safety (TCS foods), named because pathogens grow well in these types of foods. They include foods like dairy products; shell eggs; meat; poultry; fish and shellfish; baked potatoes; heat-treated plants like cooked rice, beans and vegetables; soy protein like tofu; sprouts; sliced melons, tomatoes and cut leafy greens; and untreated garlic-and-oil mixtures. TCS foods are not to be confused with ready-to-eat foods that can be eaten without further preparation or cooking – though they too need careful handling to prevent contamination.

• Poultry, such as whole or ground chicken, turkey or duck
• Stuffing made with fish, meat or poultry

•  Ground meat like beef and pork
• Injected meat like brined ham and flavor-injected roasts
• Ground seafood
• Shell eggs that will be hot held for service

• Seafood
• Steaks/chops of pork, beef, veal, and lamb
• Commercially raised game
• Shell eggs that will be served immediately

• Roasts of pork, beef, veal, and lamb

• Fruit, vegetables, grains, and legumes (i.e. beans) that will be hot held for service

If a customer requests a lower temperature, you should inform them of the risk to foodborne illness. It’s important to also note that cooking to the correct temperatures reduces the risk of pathogens, but won’t destroy any toxins or spores that may have produced, so you must still handle the food correctly, following proper food safety techniques, prior to cooking.

It’s also important to always keep the temperature danger zone top of mind. Bacteria grows between 41ºF and 135ºF, and even more rapidly between 70ºF and 125ºF, so it’s critical food never falls into this range. To prevent, it’s not only important food is cooked to it’s minimal internal temperature, but also held at correct temperatures. Frequent monitoring needs to be an essential part of any commercial foodservice. Read more about food safe temperatures, the temperature danger zone and how to avoid time-temperature abuse here. 

In order to ensure your food reaches the proper internal temperature and held at food safety temperatures, it is important to know how to effectively check it. To do this, you must first select the right thermometer. There are three main types of thermometers you’re likely to come across, and four basic types of probes.

A common type of thermometer, bimetallic stemmed thermometers can check temperatures from 0°F to 220°F, making it a great tool to check products throughout the flow of food process, from receiving to periodic monitoring while serving in a hot or cold holding unit. One of the main features of these types of thermometers is the metal stem with a dimple. The sensing area goes up the stem to the dimple, so when using to check temperatures, you must make sure it’s inserted far enough to reach. It’s great for checking temps of large or thicker foods, but not practical for thinner products. 

These two types of thermometers are relatively similar, the only difference being the technology inside. Unlike bimetallic thermometers, the temperatures are displayed digitally and the sensing area is on the tip of the probe, making them great for checking both thick and thin foods because you don’t have to insert as far into the product.

A less common type of thermometer is infrared laser thermometer which are sometimes used to measure the temperatures of food and equipment surfaces. The main positives to this type are that they’re quick and easy to use, and do not need to touch the surface of a product to get their temperature, meaning there is less chance for cross-contamination to occur. However, they have their limitations. They can’t measure air temperature or the internal temperature of foods.

After determining which of the above types is right for you, the next step is to select the correct probe. There are four main thermometer probe types.

Deriving its name because of the need to immerse, predominately used to check the temperatures of liquids such as soups, sauces or frying oil.

Used to check the temperatures of flat cooking equipment, like griddles.

This is the probe type you’re likely to use to check the internal temperature of food.

Used primarily to check the temperatures inside coolers and ovens.

To correctly check temperatures to make sure food has reached its minimum internal temperature, make sure to pick a thermometer with a probe that is the correct size for the food. For roasts or big cuts of meat, you may opt for a bimetallic thermometer with a penetration probe. For thin products, like hamburger patties, you’ll likely opt for a thermocouple thermometer.

Insert the probe into the thickest part of the food and wait for the reading to steady. Bimetallic thermometers traditionally take a little longer than digital thermometers. Allow at least 15 seconds, and then take a second reading in different locations to confirm it is safe to serve.

A thermometer used to take the temperature of foods must be accurate within (+ or -) 2°F. Over time, thermometers lose their accuracy and must be calibrated to regain it. They should always be calibrated after they’ve been bumped or dropped, have been exposed to extreme temperature change, before new deliveries arrive, and before each shift. Some thermometers cannot be calibrated and must be replaced while others may need to be sent back to the manufacturer to have calibrated. It’s important to always follow the manufacturer’s directions regarding calibration, however, the most common method for calibrating a thermometer is known as the ice-point method.

To calibrate using the ice-point method:

1. Fill a large container with ice (crushed ice preferred if available). Add tap water until the container is full. 

2. Put the thermometer stem or probe into the water, ensuring the sensing area is submerged. Hold for 30 seconds, or until the indicator stops moving, careful not to let the stem touch the container.

3. Adjust the thermometer so it reads 32°F. For a bimetallic stemmed thermometer, you’ll adjust by holding the calibration nut with a wrench or similar tool.

Chase joined Central Restaurant Products in February 2016 as a Content Specialist, bringing to the role years of various foodservice experience, including front-of-house service (slingin’ chicken wings and libations with a smile on his face) and back-of-house food prep using heavy-duty commercial cooking equipment to prepare for peak dining hours at his university’s dining hall.

He puts this experience to use writing for Central’s Resource Center, website, and print catalog. ServSafe certified, he enjoys educating on food safety in the commercial setting, researching new dining room and tabletop trends, and sharing innovative solutions to enhance operational efficiencies. He also enjoys (in no specific order) long hikes with his dog, bingeing 90s sitcoms, red wine, and live music.