How do you make food packaging from cheese whey?

By the Compost Ready editors · Updated 12 October 2026

There are two quite different routes. You can use the proteins in whey to make edible films and coatings, or you can feed the sugar in whey to bacteria that turn it into PHA, a biodegradable plastic. The second route is the one the YPACK research project followed.

This address once held a 2019 news post from the YPACK project website. The project has ended, and this is a new article written independently by Compost Ready. See About YPACK.

What whey is, and why dairies have alot of it

When milk is turned into cheese, the proteins called caseins clump together into curd. The greenish-yellow liquid left behind is whey. It still contains lactose (milk sugar), the so-called whey proteins, minerals and a little fat.

Because most of the volume of milk ends up as whey rather than cheese, cheese making produces large quantities of it. Much of it is processed into valuable products, such as whey protein powders for sports nutrition and food ingredients. But not all of it, and smaller dairies in particular may struggle to find a use. Untreated whey is rich in organic matter, so pouring it away puts a heavy load on wastewater treatment and on rivers. That makes it an obvious candidate for turning into something else.

Route 1: whey protein films and coatings

Whey proteins can form thin, transparent, flexible films when they are heated in water with a plasticiser such as glycerol and then dried. The heating unfolds the proteins so they link up into a network.

These films have some good properties. A 2024 review of whey-based materials describes them as effective barriers to oxygen, aromas and oils, especially in dry conditions. Their weakness is water. Whey proteins attract moisture, so the films soften and the barrier drops as humidity rises, and they are only moderately effective against water vapour.

In practice, whey protein films and coatings are studied for:

• edible coatings on cheese, fruit and nuts, to slow moisture loss and oxidation;
• carriers for antioxidants or natural antimicrobials;
• thin oxygen-barrier layers inside multilayer packaging, protected from moisture by other layers.

Because they are made of milk protein, they must be labelled as a milk allergen when used on food. More on this route in our article on edible food packaging.

Route 2: feeding whey to bacteria to make PHA

The second route uses the lactose rather than the protein. Many bacteria can live on sugars and, under the right conditions, store surplus carbon as PHA, a polyester that collects as granules inside their cells. Extract the granules and you have a plastic that can be made into films, trays or coatings, and that microbes can break down again later.

The steps look roughly like this:

1. Prepare the whey. Proteins are often removed first, both because they are valuable and because the bacteria mainly need the sugar.
2. Ferment. Bacteria, sometimes a pure strain and sometimes a mixed culture, grow on the whey sugars. Then a nutrient is limited so they switch to storing PHA.
3. Extract. The cells are broken open and the PHA is separated and purified.
4. Process. The polymer is compounded and turned into packaging, just like other plastics.

The type of PHA depends on what the bacteria are fed and how. From whey, researchers often obtain PHBV, a copolymer that is tougher than the simplest PHA, PHB. Changing the feeding conditions changes the share of the "V" part, hydroxyvalerate, which in turn changes how the plastic behaves. Our PHA guide explains the material in more depth.

What the YPACK project did with whey

YPACK was an EU-funded research project that ran from November 2017 to April 2021, coordinated by the Spanish research council CSIC. Its aim was to develop two PHA-based food packaging formats, a tray and a flow-pack bag, using by-products of the food industry, specifically cheese whey and almond shells, and to test them on fresh food.

Several of the project's published studies dealt with whey-derived PHBV. One, published in Biomacromolecules in 2021, made "biopapers" from cheese whey PHBV with different hydroxyvalerate contents using electrospinning, a technique that draws the polymer into ultra-thin fibres with an electric field, and then studied how the HV content affected the material. Other project papers used food-waste-derived PHBV as the base for antimicrobial and oxygen-barrier layers. The full list is on our publications page.

Where the research stands

Whey-based PHA works in the lab and at pilot scale. The open questions are mostly economic and practical: how to keep fermentation yields high with a variable raw material, how to extract the polymer cheaply, and how to collect enough whey in one place to justify a plant. Production costs remain higher than for conventional plastics, which is a common theme in reviews of PHA packaging.

Whey protein films face a different hurdle, the humidity problem described above, which is why they are most promising as coatings or as protected inner layers rather than as stand-alone wraps.

Either way, the idea behind both routes holds up: a dairy by-product that would otherwise be a disposal cost becomes the raw material for something useful.