Agriculture News

June 25, 2019

Celebrity chefs could reduce foodborne illnesses, study says

WEST LAFAYETTE, Ind. – Foodborne illnesses sicken more than 48 million people in the United States each year, with 128,000 requiring hospitalization and 3,000 dying, according to the U.S. Centers for Disease Control and Prevention. Preparing food using thermometers correctly to ensure that it is cooked well enough to eliminate pathogens and bacteria could save some of those lives.

A Purdue University analysis shows that few people use thermometers, however, if they even know how. One major factor is that they draw inspiration from celebrity chefs, magazines and food blogs that rarely mention the importance of proper temperatures.

“We see that celebrity chefs simply rely on time estimates in their recipes or cut through the meat to show there is no blood or pink. That doesn’t always mean the food is safe, however,” said Yaohua "Betty" Feng, an assistant professor of food science at Purdue, whose results were published in the Journal of Food Protection. “That affects the behaviors of home cooks and professional cooks. If their role models aren’t using thermometers, why should they? But if chefs preparing food on television or social media would include the use of a thermometer to ensure the food is thoroughly cooked, it would have an impact on their viewers.”

Feng and Christine M. Bruhn of the University of California, Davis, analyzed 85 studies from over two decades to understand knowledge, attitudes and behaviors associated with thermometer use. Despite it being considered a best practice in home and professional kitchens, thermometer use is low.

In one study, two-thirds of people reported owning a meat thermometer, but less than 20% used it all the time to check the temperature of chicken, and less than 10% used it all the time for hamburgers. About half of consumers say that thermometers aren’t necessary to check the doneness of egg or meat dishes.

One of the top reasons given is that role models, such as celebrity chefs, restaurant managers, cookbook authors and bloggers, rarely use temperatures to signify when a dish is cooked completely.

“Use of a cooking thermometer is seldom mentioned in recipes developed for consumers. Printed recipes describe cooking time and oven temperature but rarely list recommended endpoint internal temperature,” the authors wrote. “A recent evaluation of popular cookbooks revealed that only 8% of the recipes containing raw meat included an endpoint temperature, and in 28% of those recipes, the temperature provided was incorrect.”

Analyses of television cooking programs found that 45% to 75% of episodes do not show use of a cooking thermometer, and only 12% mention the correct cooking temperatures.

Feng also noted that many people are unsure which type of thermometer to buy or how to correctly use them, including where to place the thermometer in the food, the correct endpoint temperatures, proper temperature calibration for the thermometer, and proper cleaning and sanitation. About 95% of people in one study did not clean their thermometers after use.

“We see people check chicken that isn’t done, and then they set the thermometer on a plate or on the counter, contaminating those surfaces,” Feng said. “Later, they’ll use that unsanitized thermometer to check chicken again, potentially introducing pathogens to the food.”

Some studies monitoring those using thermometers noted that some cooks did not remove the plastic probe cover before trying to check the temperature of meat. In other studies, cooks believed they could simply tell when food was done. Quotes from those cooks included: “I just look at it, you know, and you can tell it's done. But I don't even know what the real temperature should be.” And “I wiggle the turkey leg. If it's loose, I guess it's done.”

The Partnership for Food Safety, recognizing the need for consumer guidance in use of a food thermometer, has recommended recipes include endpoint internal temperatures be part of every recipe. For more information visit

The U.S. Department of Agriculture National Institute of Food and Agriculture’s Agriculture and Food Research Initiative supported this research. 

Media contact: Maureen Manier, 765-494-8403,

Source: Betty Feng, 765-494-0331,  


Motivators and Barriers to Cooking and Refrigerator Thermometer Use among Consumers and Food Workers: A Review

Yaohua Feng1, Christine M. Bruhn2

  1. Department of Food Science, Purdue University, West Lafayette, IN
  2. Department of Food Science and Technology, University of California, Davis, CA

Temperature control prevents the rapid growth of foodborne pathogens during food storage and assures adequate heating to destroy pathogens prior to consumption. The use of thermometers is a recognized best practice among consumer and food worker guidelines; however, compliance with this recommendation is quite low. Eighty-five studies from the past 21 years were reviewed and an analyzed for the knowledge, attitudes, and behaviors associated with thermometer use and the motivators and barriers to cooking and refrigerator thermometer use among consumers and food workers. Barriers to thermometer were categorized into two major groups: “the belief that a thermometer is not necessary” and “the difficulty of selecting and using a thermometer.” Each group has its unique aspects. Four barriers were recognized in the “not necessary” group: (i) preference for alternative techniques, (ii) mainstream media and food professionals seldom serve as role models and often negate the need for food thermometers, (iii) limited awareness of potential health issues associated with current practices, and (iv) limited knowledge and awareness related to thermometer usage for specific food groups. Six barriers were recognized in the “difficult to select and use” group: (i) difficulties in selecting the type of food thermometers, (ii) availability of food thermometers, (iii) lack of skills related to the usage of food thermometers, (iv) limited knowledge related to endpoint temperatures, (v) inability to calibrate food thermometers, and (vi) lack of knowledge about food thermometer cleaning and sanitation. These findings will facilitate the development and adoption of effective strategies to increase thermometer use and increase food safety education efficacy with a positive impact on public health.

Agricultural Communications: 765-494-8415;

Maureen Manier, Department Head,  

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