When you think about industrial-scale food preservation, it's unlikely that old-fashioned Mason jars come to mind. Until relatively recently, however, most food manufacturers relied on processes similar to traditional canning. While such hot-fill methods produce shelf-stable products, they necessitate expensive packaging and can compromise product integrity. 

Enter aseptic processing and packaging. This ever-growing technology has changed the face of beverages, baby foods, and more.

For the past three decades, Steve Smith has spearheaded some of the most exciting developments in aseptic processing. Currently a Processing Specialist, Smith has been developing aseptic technology at Purdue University's Food Science Pilot Laboratory for 29 years. Now, up to 50 food manufacturers each year visit the state-of-the-art facility to learn about new technologies.

We spoke with Smith about where aseptic technology has been and what compelling developments he sees coming down the road.

Aseptic Basics: Less Package, Lower Cost

One of the top drawbacks of hot-fill preservation is its reliance on heavy-duty packaging. Only metal cans, glass jars, and certain extra-resilient plastics can withstand the time and temperature needed to make products commercially sterile. And these materials don't come cheap. According to Smith, when consumers buy products sterilized in this way, they're paying two to three times more for the package than they are for the product!

So how does aseptic technology allow companies to package more cheaply?

In aseptic processing, the food product and the package are sterilized separately. The package — which can be made of plastic, paperboard, or other thinner materials — is sterilized with gamma radiation, hydrogen peroxide, or peracetic acid. The product is heated in plate heat, tubular, or scraped surface heat exchangers. Because the product is heated on its own, it can be heated within a very thin profile — brought up to a sterile temperature and cooled back down very rapidly.

The cooled product is put into the package via an aseptic/sterile filler. Because the product is already cool, it won't compromise the thinner — and less expensive — packaging.

Aseptic Processing by the (Million) Gallon

Aseptic processing provides a benefit to more than just processors and consumers. The technology is also useful for packaging very large amounts of product to be used by other food manufacturers. For example, it's very expensive to can large amounts of tomato paste in the traditional way and then ship it to manufacturers who use it as an ingredient.  

Aseptic technology allows the product to be processed in larger containers and packaged in 300-gallon tote bins.

First, the bin, which has a large, flexible package inside, is sterilized with gamma radiation. Then the paste is sterilized and put through the aseptic filler into the bins, and the relatively lightweight, completely sterile product is ready to go.

Another success story is that of aseptically processed not-from-concentrate orange juice.

The Purdue Lab worked with Tropicana to develop a method to safely store juice during the long Florida processing season. The lab developed million-gallon tanks, which are sterilized with an iodine solution. As the juice moves through the plant, it's heated to sterile, cooled back down, and filled into the tanks. At this point, the juice is microbially shelf-stable — and with refrigeration, it will stay fresh for well over a year.

The juice can then be packaged on demand. It just needs to be pumped out of the tanks, repasteurized, and put in the traditional, gable-top containers. At this point, it has “extended shelf life,” but is no longer truly sterile.

Since Purdue developed this technology for Tropicana, other companies like Coca-Cola and Florida Natural have adopted it as well.

Even more amazing is how aseptic technology has made the leap from land to sea.

Over half of the orange juice distributed throughout the world comes from Brazil. Smith's lab developed an aseptic ship, which contains 18 half-million gallon tanks, which keep the juice sterile as described above. Today, thanks to Smith and his colleagues at Purdue, five aseptic ships are traveling the ocean at any given time, bringing orange juice to North America, Europe, and Asia.

New Frontiers in Sterilization

The rise of aseptic processing has also paved the way for innovation in sterilization technologies.

Microwave thermal processing is one of the most promising up-and-comers. As we explored in a previous blog post, this technology heats product volumetrically.

It works incredibly quickly, heating product at 5 gallons per minute from 45°F to 285°F in less than one second. The fast heating means that less heat is put into the product, which means the retains its integrity.

Smith admits that he was skeptical about the benefits of microwave until he tried the spinach puree. Canned spinach is not on most people's favorite foods list. But microwave thermal processing could change that.

As a proof of concept, Smith's colleagues used microwave thermal processing to heat spinach puree to 285°F to make it shelf-stable and then packaged it aseptically. When Smith opened the package, he discovered that, lo and behold, “It was bright green and tasted like spinach!”

There are also some promising new technologies to sterilize aseptic packages. For example, Tetra Pak recently launched a filling machine that uses electron beams (or e-beams). The packaging is passed through an e-beam that sterilizes the materials almost instantly.

This technology has numerous benefits over hydrogen peroxide, which has been traditionally been used to sterilize packaging. For one, e-beam technology doesn't use chemicals. Also, hydrogen peroxide requires close monitoring, because the Department of Homeland Security considers 35% hydrogen peroxide a security risk (for its explosive capability). E-beams don't need to be monitored as closely.

There's also that Holy Grail of industry — e-beams save time, and thus money. A 2015 article in Food Engineering magazine reports that the speed of the e-beam sterilization process can save beverage manufacturers 20% in operational costs. The process is also considerably more energy and water efficient.

Smith is also keeping his eye on the use of aseptic processing for low-acid particulate foods like vegetable soups and chunky meat soups.

The FDA has particularly stiff requirements for these products, since products with a pH above 4.6 can support the growth of pathogens. Smith says that a few companies are close to figuring out how to make the aseptic process work for these riskier products — so much so that they've received “letters of non-objection” from the FDA, which is as good as approval.

Overcoming the Odds

As much as a fan as Smith is of aseptic packaging and processing, he recognizes that there are some barriers to widespread implementation.

To start with, aseptic fillers — which are needed to put the sterile product into a sterile container — are expensive, running between $5 and $10 million for cup and bottle fillers. But the cost savings in packaging are considerable. Smith notes that one company that switched from hot-fill to aseptic processing saves about $1 million per quarter on packaging alone.  

There's also the simple fact that the food processing industry can be slow to change. Profit margins are much lower here than in other industries, and no one wants to be the first to take a risk. But, Smith notes, “it's like a tidal wave — once someone starts the motion, everyone jumps on board.” 

And the food processing industry does seem to be “jumping.”Food Engineering recently reported that the demand for aseptic packaging in the United States is climbing. Use of the technology is expected to increase 6.8% per year through 2020, ultimately hitting a value of $6.4 billion.

Industry and Academia: A Perfect Partnership

Finally, Smith is particularly proud of how academia and industry have worked together to bring aseptic technology to the mainstream.

It's a mutually beneficial partnership. Industry likes working with universities because labs aren't there to push products or try to make a sale. They're there to do research and share what they've learned. As Smith says, labs like his are “a conduit of technology.”

The partnership benefits the university as well. Students get hands-on experience working with products in the lab, and they often go on to work for companies that the university has developed relationships with. And acclimating themselves to the more bottom-line-oriented mindset of industry helps the university facility run more efficiently.

Smith's enthusiasm for this productive relationship is infectious. He says, “I absolutely love to work with industry because there is a benefit to the industry and a benefit to the university, and to equipment manufacturers, packaging suppliers — to everybody — in working together.”

We've heard this sentiment before in our interviews with other FPSA members. Let's hope the future brings more of these partnerships, as well as the technology and process improvements — like aseptic processing — that come out of them.

Learn more about microwave thermal processing from our Expert in Residence, Steve Smith.