UNL Team Receives Grant Funding to Improve Low-Moisture Food Safety

May 29, 2015

Lincoln, Neb. — A team from the University of Nebraska-Lincoln has received a portion of a $5 million USDA food safety grant to enhance low-moisture food safety by improving development and implementation of pasteurization technologies. UNL will receive $943,617 over five years.

Low-moisture foods, such as nuts, spices and peanut butter, have been considered at low risk for foodborne illness because they are consumed in a dry state. While microbial growth isn't possible, the bacteria can survive and stay on the food product for a long time. Foodborne pathogens, such as salmonella, can cause illness even at very low levels. 

"You don’t need a million bacteria to cause illness; as few as 10 cells can cause illness," said Harshavardhan Thippareddi, UNL Department of Food Science and Technology professor and Nebraska Extension food safety specialist. Thippareddi is a project director on the USDA grant. "So even though the bacteria do not grow on these types of products, if you have a very low number present, they can survive for long periods of time and cause illness to sensitive populations." 

Outbreaks and recalls due to salmonella and other foodborne pathogens led Congress to pass the Food Safety Modernization Act in 2011, which mandated that food processors guarantee the safety of their products. The issue food processors are facing is that it is extremely difficult to kill bacteria on low-moisture products. Current pasteurization methods take a significant amount of time and frequently hurt the quality of the food product. UNL research will focus on improving and developing technologies that can kill the bacteria while not affecting food quality. 

Jeyamkondan Subbiah, Kenneth E. Morrison Distinguished Professor of Food Engineering with the biological systems engineering and food science and technology departments and a project director on the USDA grant, said research on bacteria in low-moisture products isn't where it needs to be because people have always thought these products were safe. 

"Now that the risk has been recognized, we need to find technologies to improve their safety and validate the effectiveness of the technologies," he said.

Subbiah's research will look at radio frequency and extrusion processing of the low-moisture products to inactivate the bacteria. Traditional heating will heat the product from outside to inside, whereas technology using electromagnetic waves such as radio frequency waves will volumetrically heat the product. With these methods, the impact on food quality is minimal because the food can be more evenly heated throughout the product to inactivate bacteria

Along with research, extension is a critical part of this grant. UNL will disseminate its findings to local food processors in Nebraska and across the country and work with them to meet new food safety regulations. 

In addition to UNL, principal co-investigators on the project are Michigan State University, Washington State University, Illinois Institute of Technology and North Carolina State University.


Harshavardhan Thippareddi
Department of Food Science and Technology
402-472-3403
harsha.thippareddi@unl.edu