Apple of my eye: Oregon State researchers convert pomace into plastic-replacement packaging
18 Feb 2022 --- An Oregon State University study in the US has demonstrated that apple waste can be turned into a renewable packaging material that could serve as an alternative to conventional plastics.
Oregon State professor Yanyun Zhao, who leads a research team focusing on environmentally sustainable food packaging and processing, studied the processing waste generated after apple juice manufacturing (known as apple pomace) to find alternatives for recycled newspaper in molded pulp manufacturing.
“Right now, apple pomace is typically just composted or used for animal feed,” says Zhao, whose research aims to reduce food loss and waste across the food supply chain. “We thought why not turn it into an environmentally friendly product that meets an industry need.”
Zhao envisions apple pomace as the main ingredient in molded pulp packing products such as take-out containers, flower pots, beverage cartons, bottles, and clamshell packaging used for fruit and vegetables.
She is focused on apple pomace in part because it is readily available in the Pacific Northwest. When apples are processed for juice, about 70-75% of the apple goes into the juice, leaving the remaining 25-30% as pomace.
The research team also studied other byproducts from processing fruit and vegetable juice and winemaking, earning a patent for their research.
Improving water resistance
One of the key problems in creating pomace and paper-based packaging is improving water resistance to withstand high moisture, liquid food or non-food items and products stored under high humidity conditions.
A key challenge in creating pomace and paper-based packaging is improving water resistance.As explained in a recently published paper in Food and Bioproducts Processing, the team sought to create bio-based, compostable and cost-effective solutions that would improve the hydrophobicity or water resistance of the apple pomace-based molded pulp products.
The researchers used two strategies: incorporating polymers and compounds with characteristics to improve water resistance into the pulp formulation and applying superhydrophobic coatings on the product surface.
The polymers and compounds studied include lignin, chitosan and glycerol.
Lignin is a polymer that forms key structural materials in the support tissues of most plants. Rhubarb pomace, which is particularly lignin-rich, was used in this study.
Chitosan is a bio-based polymer commonly used in the papermaking industry. A previous study from Zhao’s team found that chitosan reduced water absorption of cellulose nanofiber (CNF) films significantly through adsorption of chitosan onto CNF fibers via hydrogen bonds.
Meanwhile, glycerol is an organic compound often added to a material to make it softer and more flexible. Previous studies have shown that glycerol decreased water absorption at low levels.
The researchers determined the optimal amounts of those polymers and compounds while also adding a small amount of cardboard fiber for stability in the molded pulp packaging.
Apple pomace is typically composted or used as animal feed.Beyond recycled newspaper
Recycled newspaper has traditionally been the main ingredient in molded pulp packaging products, which have become increasingly popular for their compostability. However, the supply of recycled newspapers is in decline, creating a market for substitute materials.
In related news, Innofibre recently released new research data validating HP’s Molded Fiber Advanced Tooling Solution. Based on its testing, the independent Canadian research institute confirms HP’s technology can offer greater precision, along with faster forming and drainage times.
Furthermore, International Paper, a leading renewable fiber-based packaging and absorbent pulp solutions producer, set a new production record at its Spanish mill in Madrid in the last quarter of 2021.
The mill reached a total production volume of one million tons of high-performance, lightweight recycled containerboard after the completion of a conversion investment in August 2018.
By Natalie Schwertheim
