Using biomaterials to develop bale wrap and silage cover

Reducing landfill waste and single-use plastic consumption are the goals for researchers at the University of Guelph who are developing hay bale and silage covers from biomaterials.

Dr. Erica Pensini, a professor in the school of engineering, and a team of researchers, including Dr. Alejandro Marangoni, a professor in the department of food science, are developing a spray-on coating produced from corn byproducts to replace petroleum-based plastic wrap used on hay bales. This solution would greatly reduce landfill waste by converting food byproducts into a usable product that decreases the need for plastic bale covers.

“Our objective is to create a biodegradable product that meets farmers’ needs,” Pensini says. “We’re developing a robust product that can be composted on the farm without the need of special facilities.”

Bales are often wrapped in plastic to retain hay quality and nutritional value.

“Unfortunately, most of this plastic wrap can’t be recycled and ends up in the landfill,” Pensini says. “This is why it’s important to use bio-based products, such as zein, which is a corn protein byproduct that already exist, and not use ones we need to produce synthetically.”

The biodegradable bale cover Pensini is developing requires only a few ingredients, mainly zein. It begins in powder form, and when mixed with water, can be sprayed onto the bale surface, Pensini says.

Zein becomes water-insoluble and hardens after combining with salt or acetic acid. While the covering can be biodegraded after use, it’s also edible, which means cattle can safely consume the zein formulation along with the hay. This leaves zero waste in the end and uses leftover byproduct from corn.

Researchers have studied new formulations to further strengthen the zein coating and make it inaccessible to unwanted animals, such as rodents that might eat the coating and cause feed loss.

“The covering retains its structure when sprayed on a surface,” Pensini says. “It also successfully locks in moisture.”

She is also looking to develop prefabricated zein wraps as an alternative to the spray coating.

Other biodegradable plastics are being developed by organizations, but many can be degraded only in special facilities and are costly. Pensini’s bale coating would be strong enough to withstand silage fermentation and field conditions in low and high temperatures and can also be broken down safely in soil.

Zein has many uses aside from covering hay bales, Pensini says. It can be used for drug encapsulation, candy coatings and water-resistant coatings on paper cups and plant pots. “While recycling petroleum-based plastic is good, it doesn’t get rid of the problem at hand, which is we are continually accumulating more waste by creating more plastic,” Pensini says. “It would be more ideal if we didn’t have to rely on plastic as a tool in the agricultural sector.”

This research is funded by the Ontario Ministry of Agriculture, Food and Rural Affairs through the Ontario Agri-Food Innovation Alliance, as well as Dairy Farmers of Ontario.

This story was written by SPARK and originally published in Milk Producer, October 2021.