New Radiofrequency Pasteurization and In-Package Steaming Is Food Safety of the Future

A new study out of the University of Arkansas using radiofrequency pasteurization and in-package steaming could be the answer low-moisture food manufacturers have been looking for.

Food safety scientists are always looking for ways to make food safer, while keeping the process affordable and maintaining product quality. It is a balancing act for sure.

Researchers from the University of Arkansas may have found a way to check all of those boxes. Even in the target of the often-problematic low moisture food category.

The Problem with Low Moisture Foods

Surabhi Wason, Ph.D., lead author of “Radiofrequency inactivation of Salmonella in Black Pepper and Dried Basil Leaves Using In-Package Steaming,” of the University of Arkansas Division of Agriculture was looking for a novel approach to pasteurizing or sanitizing low moisture food products.

While a long-researched topic, a recent national recall of black pepper in response to Salmonella contamination risk brought the concept to the forefront of public discussion.

How can you effectively sterilize low moisture foods without potentially introducing unwanted variables?

“Food processing plants that process low-moisture foods clean [their facilities] less frequently, often once a year.” This is due to the increased food safety risks associated with introducing water into the plant environment.

This long-exercised practice has its pros and cons.

For the “pros,” maintaining strict sanitation protocols reduce the need for full facility sanitation practices.

The “cons.”

During a recall, a food manufacturer must pull everything produced after the previous cleaning.

This could mean several days or even months of production material subject to recall.

Additionally, any other product that used the recalled product as an ingredient must also be recalled. This could mean thousands of products must be pulled. The downline effects can be exponential. Particularly for spices.

This is a potentially huge financial loss.

“People don’t realize the magnitude of food safety,” says Wason.

Traditional Methods Use High Temperatures

Traditional methods rely on high temperatures for long periods of time to kill bacteria. This is the way foods have been sterilized for decades (or longer).

Unfortunately, some pathogens are sneaky and can survive and adapt in those harsh environments. Even stay hidden for years.

Then, when conditions are right. Bam! They begin to grow and reproduce to infectious numbers. For example, spices being added to broth in a soup or tea bags being steeped in hot water.

Not a good situation. Not good at all.

Especially because one of those low-moisture foods subject to this type of sterilization is infant formula. Recent issues with Campylobacter contamination in infant formulas that resulted in nationwide formula shortages are a prime example of when low-moisture foods become contaminated.

Additionally, severe heat treatment can affect product quality, nutrient composition, texture, or damage packaging.

High temperature sterilization methods may be the tried-and-true methods. But are there better ways?

Irradiation as a Sterilization Method

Investigators concede that pasteurization methods through irradiation or radiation exposure are also successful options. Under these sterilization methods, food products are exposed to low levels of radiation meant to destroy DNA or RNA found in microorganisms or viruses, neutralizing them and effectively killing them.

However, consumer acceptance is low.

Many people associate radiation with glowing green rods as seen on a popular cartoon sitcom and energy manufacturing facility meltdowns. Even though different types of radiation with negligible half-lives are used in these types of applications and are completely safe.

Researchers Were Inspired by Steam-in-the-Bag Foods for In-Package Steaming Approach

In addition to generating an effective sterilization method, researchers also wanted to pose an approach that was favorable to food manufacturers.

If it is difficult to perform or not cost-effective, it is unlikely to be accepted in mainstream applications.

Researchers admitted the idea for the in-package steaming technology was inspired by microwavable vegetable packaging. Could this same approach of in-package steaming translate to quick heating of dry foods and self-resealing packages work, pondered Jeyam Subbiah, head of the University of Arkansas Food Science Department and corresponding author of the paper?

The challenge? Preventing steam buildup that may potentially compromise the packaging.

The solution? A one-way valve that releases produced steam and then reseals the packaging.

This novel technology mimics the time-tested in-package sterilization used in canned goods. But with more predicable radiofrequency heating instead.

What is Radiofrequency Heating and How is it Used in In-Package Steaming Applications?

While conventional heating methods heat the surface, taking longer to reach the center of the food, radiofrequency heating has an entirely different approach.

Radiofrequency heating generates heat evenly throughout the mass of the product. Sufficient heat is obtained by vibrating water molecules in an electric field. If this sounds familiar, it is quite similar to the technology used in the microwave appliance found in most homes.

The benefit?

Uniform heating within the final packaging. This in-package steaming reduces the risk of contamination between sterilizing the product and placing it in the final package.

In addition to streamlining the packaging process, fewer product transfer steps leads to fewer opportunities for cross-contamination. It can even be performed on a conveyer system, as the product moves from one part of the facility to another.

What Kinds of Foods Can Benefit from In-Package Steaming Applications

Many different kinds of foods can benefit from in-package steaming applications. The primary example is dry goods or those categorized as low-moisture products.

Low-moisture foods are food products with a water activity equal to or less than 0.85. Things like breakfast cereals, grains, dairy and egg powders, dried fruits and vegetables, chips, snacks, herbs, spices, chocolate and cocoa, seeds, nuts, and honey are primary examples. The list can go on and on.

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By: Heather Van Tassell (contributing writer, non-lawyer)