Keeping Farmstead Cheese Sealed: Packaging Shelf-Life for Small Creameries

The question

Porter County has nine small creameries that make cheese from their own herds or from a neighbor’s milk. Most sell cut, vacuum-packed wedges at the Depot Plaza farmers market, in regional grocery stores and by mail. In 2025 the Porter County Cheesemakers Guild surveyed its members and found that between 3 and 9 percent of retail packs were coming back: mold under the film, “leakers” that lost vacuum in the case, and puffy packs in the summer months. For a creamery making 40,000 pounds a year, that is real money and a worse problem for reputation.

The guild assumed the answer was a better barrier film and asked Dr. Grace Nakamura, assistant professor of plastics and packaging engineering, which one to buy. She proposed testing that assumption first.

The approach

The project runs out of the Center for Packaging Innovation, with microbiology support from the Fermentation & Food Innovation Laboratory. It has three parts:

1. Return autopsies. Each creamery saves its failed packs in a freezer bag with a date and store. Students open them, dye-test the seals, measure residual oxygen in the headspace and photograph the failure.
2. Shelf-life trials. Four films with different oxygen transmission rates, packed on the creameries’ own machines, stored at 38 °F in the dark and under retail case lighting, and pulled every two weeks for up to 20 weeks.
3. Line visits. Students spend a packing day at each creamery with a stopwatch and a checklist, watching how the cheese is loaded, how long seal bars dwell and how often they are cleaned.

Pulled samples go to a trained sensory panel in FDSC 3300 Sensory Evaluation, because a pack that keeps its vacuum can still taste like cardboard after a month under fluorescent light.

Students on the team

• Hallie Brekken, senior, packaging — student lead; runs the shelf-life schedule and the return autopsies.
• Omar Shalabi, junior, packaging — seal-strength and leak testing.
• Lucy Her, junior, food science — mold and yeast counts in the fermentation lab.
• Peter Rusch, sophomore, packaging — line visits and the creamery checklists.
• Nadia Ostrowski, sophomore, food science — sensory panel coordination.

Two of the five grew up on dairy farms; one of them had packed cheese at a family creamery every summer since she was twelve, which turned out to be the most useful qualification on the team. Nakamura’s rule for line visits is that students watch and write down before they suggest anything: a creamery packing 300 wedges on a Friday afternoon does not need advice from a sophomore, it needs an accurate description of what is happening at the seal bar. Each visit ends with a one-page summary sent to the cheesemaker within a week, and nothing is shared with the rest of the guild without that creamery’s permission.

What they found so far

After 14 months and 412 returned packs:

• 61 percent of failures were seal-channel leaks — tiny wrinkles in the film across the seal line, almost all on hand-loaded chamber machines when a wedge was placed off-center or the bag was not smoothed before sealing.
• Only about 12 percent traced to the film itself. Two films performed nearly identically in the dark; the cheapest film was the worst under case lighting.
• A $40 loading guide — a cut acrylic plate that centers the wedge and tensions the bag — designed by a student and made in the Forge Prototyping Lab, cut leakers at the first two creameries that tried it from 6.8 percent to 1.9 percent of packs.
• Puffy summer packs were mostly gas from the cheese itself, not contamination. Those creameries now hold younger cheeses a week longer before cutting.

“Everyone wanted the answer to be a better film because you can buy a better film. The answer was how you put the cheese in the bag, which you can fix for forty dollars and a morning of practice.”

— Hallie Brekken, senior, packaging

What’s next and who’s involved

The loading guide is being rolled out to all nine creameries this fall, with a short training video. The team is now running a 20-week trial of light-blocking labels for the two creameries whose cheese sits longest in grocery cases. Results will appear in the guild’s spring newsletter and at the Center’s annual open house.

Partners: the Porter County Cheesemakers Guild (nine member creameries, $24,000 in member contributions and product) and a regional grocery cooperative that shares return data. The main award is $118,000 over two years from the Wesconsin Value-Added Dairy Grants program. Students who want in typically come through PKG 3500 Food and Pharmaceutical Packaging.