Envision a scenario that’s relatable to many consumers: Using a pair of scissors to open a bag of cheese that has a tear-off perforation.

That’s exactly what Jonathan Quinn saw when a family member cut off the resealable closure, before they folded the open packaging over to wrap up with a hair tie. The CEO of the U.S. Plastics Pact said the less-than-ideal cheese bag opening incident is “what we need to hope consumers won’t do.”

Manufacturers of flexible packaging, along with the companies that make zippers and closures, have prioritized testing for function and design as resealable flexible packaging use is on the rise. CPG brands also see resealables as a way to appeal to consumers’ desire for convenience and reduce waste by preserving products for longer.

While bags of cheese have had closures for a while, the feature is increasingly appearing on other items, especially containers with multiple servings in one pack. In addition to products such as nuts, coffee and deli meat, closures have made their way to pancake and waffle mix, cereal, frozen foods, snacks and more.

Natalie Kaczorowski, business development manager at Fresh-Lock, has also observed “the premiumization of pet food, where consumers are willing to pay more for high-quality packaging with reclosable features that help maintain freshness and add convenience.”

Farm to Pet, a manufacturer of pet treats, sources its resealable bags from ePac Flexible Packaging. Jackson Jones, founder and owner of Farm to Pet, said this is driven by consumer interest in convenience and portability.

“We consider a resealable bag a must for a multi-serving product like ours,” said Jones.

The convenience factor

The growth of e-commerce has shifted some food from rigid containers to space-saving flexible packaging, Quinn said, and it has also moved some brands to develop powder-based alternatives to their liquid products for lighter-weight shipping. But consumers still want the convenience and ability to close their packaging.

When Z Natural Foods launched its organic date powder — a natural sweetener and alternative to refined sugar — in a resealable foil pouch, the brand touted benefits such as ease of opening and storage, along with long-lasting freshness. 

“Customers easily portion out what they need and securely reseal and store the bag for later use, without needing to transfer the contents to another container,” said Sam Hirschberg, senior director of marketing at Z Natural Foods. “This aligns with modern, busy lifestyles where convenience is key.”

Powdered products do best when moisture, light and oxygen are kept out, which helps to preserve freshness and “reduce food spoilage that is so common in households,” Hirschberg said. The company declined to disclose its packaging partner. 

Other products, meanwhile, require some airflow for optimal freshness and minimal food waste. Flanagan Farm sells sauerkraut in stand-up, BPA-free resealable foil pouches. The brand worked with Eagle Flexible Packaging to create a one-way valve on its bags that lets the sauerkraut continue to ferment and maintain probiotic levels. 

“The resealable ‘pinch to close’ zip at the top of the bag makes it easy to grab a quick bite of kraut anytime without mess and fuss,” said Jess Magno, senior brand manager of Flanagan Farm. 

Putting closures to the test

Reducing food waste benefits packaging suppliers, CPGs and consumers alike. But the key is for the seals to work reliably, allowing the product to stay fresh and in its original packaging. 

“We've all purchased resealable and reclosable products that failed to perform their function,” said Andrew Hurley, associate professor of packaging science at Clemson University. “This not only causes frustration, but also erodes brand equity.”

At Fresh-Lock, “every closure we develop goes through extensive testing,” Kaczorowski said. 

Seal-strength tests ensure closures continue to work over time, and environmental tests assess how closures work in various storage conditions. The teams also test for ease of use. The goal is for closures to be easy to use, but not to accidentally open if a package falls over. 

CPG brands often conduct their own tests before choosing a supplier, creating another layer of assessment before the packaging gets to consumers. Farm to Pet tests sample packaging to make sure it tears, opens and seals well. Z Natural Foods looks at ease of tearing at perforations, and it repeatedly opens and closes seals “to verify the durability,” Hirschberg said. 

Closure manufacturers and brands not only have to consider the broad consumer market when testing packaging, but also individuals with limited mobility. 

“Accessibility is a key focus for us,” Kaczorowski said. Fresh-Lock’s design process considers consumers who may have limited dexterity or strength and makes closures easy for them to open. 

Hurley said Clemson University has a lab where brands can test pre-market prototypes as well as packaging already on the market to “ensure it's accessible to consumers with limited dexterity, vision, or even color blindness.”

As important as it is to allow consumers to get into packaging, it’s also equally important to keep some of them out. Food products containing cannabis or non-edible items, such as laundry detergent pods, require child-resistant closures that meet regulatory standards.

Quinn called it “scientific gymnastics” to figure out the ideal design that keeps children out of the packaging but allows adults and elderly people to open the package without assistance. 

Some closures use a press-to-seal design. With those, especially if the product inside is a powder, Kaczorowski said suppliers have to make sure the powder doesn’t clog the lock channels and prevent the seal from closing properly.

A tactile response, such as a light snap or a Velcro-like noise, “gives the consumer a level of confidence that it's closed,” Quinn said. 

Other closures use a tab slider or zipper design. Rigid, durable zippers “lock the tightest and help to keep oxygen ingress from happening,” Quinn said. On the flip side, if the zipper “isn’t made with a tight attention to detail and quality … it’s going to impact that overall shelf life.” 

For all their potential benefits, closures can present a challenge for recyclability. Certain resealable packages are designed for store drop-off recycling programs rather than curbside, Kaczorowski said. Hirschberg said the lamination on flexible packaging makes it difficult to recycle curbside. Experts suggested making closures from the same material as the packaging substrate to better enable recycling.

Manufacturers are also focusing on alternative materials. The Fresh-Lock team is developing closures for functional paper pouches that would be curbside recyclable, and it recently launched a line of closures that the company says are “designed to biodegrade within 90-180 days under compost conditions.”

“Sustainability has evolved from being a 'nice to have' to a requirement,” Kaczorowski said. “Flexible packaging manufacturers and converters continue to evaluate ways to bring curbside recycling to flexible packaging.”