With the increased consumer and regulatory focus on sustainability and waste management, manufacturers are searching for packaging materials that are made from renewable sources and biodegrade, reducing the landfill burden.
Agricultural Research Service (ARS) researchers said they can make a water-resistant film by combining the milk protein casein with water and glycerol, a byproduct of biofuel production, The film can be used as an edible coating, which extends the shelf life of food products, claims the ARS.
"The resulting food coatings are glossy, transparent and completely edible," the ARS said.
"Like conventional food packaging, edible films can extend the shelf life of many foods, protect products from damage, prevent exposure to moisture and oxygen and improve appearance."
The process uses carbon dioxide as a solvent to isolate dairy proteins from milk.
This method is more environmentally friendly compared with the use of harsh chemicals or acids that can be difficult to dispose of, the scientists claim.
CO2, a byproduct of the glucose fermentation that is used to make ethanol, is used to make the edible film more water-resistant and biodegradable.
The ARS has been working with food a technologist and a chemist to improve the appearance and protective properties of the casein films.
During the process CO2 dissolves into the milk, which decreases its pH level and causes casein to form particles of a substance known as CO2-casein.
Decreasing the size of the CO2-casein particles improved the moisture blocking ability and increased the glossiness of the film, the scientists found.
They also found that coating a low-density polyethylene film with the CO2-casein increased the film's ability to block oxygen permeation.
The ARS said that further adjustments could make the films more competitive with existing, less eco-friendly products.