Apple waste transform into Packaging Material
A new analysis by Oregon State University scientists summarizes a fundamental advancement in shifting apple waste into an environmentally friendly packaging material that could act as an alternative to plastic.
The recycled newspaper has traditionally been the primary ingredient of so-called molded pulp packaging products, becoming increasingly popular because they are compostable. But the supply of recycled newspapers is in decline, creating a market for substitute materials.
Yanyun Zhao, an Oregon State professor who directs a research team concentrating on sustainable food packaging and processing, has analyzed apple pomace and other byproducts from processing fruit and vegetable juice and winemaking as an alternative for a recycled newspaper in molded pulp company.
His team received a patent for this research. “Right now, apple pomace is normally just composted or used for animal feed,” said Zhao, whose analysis aspires to decrease food loss and waste across the food supply chain. “We thought why not turn it into an environmentally friendly development that fulfills an industry requirement.”
Zhao expects apple pomace to be the primary ingredient for molded pulp packing products such as take-out containers, flower jars, beverage cartons and bottles, and clamshell packaging used for fruits and vegetables.
She concentrates on apple pomace because it is readily general in the Pacific Northwest. When apples are processed for juice, about 70-75% of the apple moves into the liquid, left part 25-30% pomace.
One of the critical concerns in developing pomace and paper-based packaging is enhancing water resistance to resist high moisture, liquid food, or non-food items and products stored in high humidity conditions.
In a recently-published paper in Food and Bioproducts Processing, the team pursued to make eco-friendly, bio-based, compostable, and cost-effective material that would enhance the hydrophobicity, or water resistance, of the apple pomace-based, molded pulp products.
Methodology for improving MVTR barrier
Two methods are used: incorporating polymers and compounds with features to improve water resistance into the pulp formulation and using superhydrophobic coatings on the product surface. The polymers and compounds examined include lignin, chitosan, and glycerol.
Lignin is a polymer that comprises essential structural materials in the aid tissues of most plants. Rhubarb pomace, which is especially lignin-rich, was used in this study.
Chitosan is a bio-based polymer typically used in the papermaking industry. A prior study from Zhao’s team discovered that chitosan decreased water absorption of cellulose nanofiber (CNF) films mainly through the adsorption of chitosan onto CNF fibers via hydrogen bonds.
Ultimately, glycerol is an organic compound frequently added to a material to create it softer and more flexible. Earlier studies had indicated that at low levels, glycerol decreased water absorption.
The researchers determined the optimal amounts of those polymers and compounds while also adding a small amount of cardboard fiber for the stability of the molded pulp packaging products. Zhao’s team has a long history of studying food coatings as a barrier to water and gases.
The team had previously created a two-step preparation of a superhydrophobic layer that is heat, cold, and water-resistant. It used a simplified, one-step coating on the surface of the apple pomace-based product to improve water resistance.
They figured that the study showed the feasibility of using fruit pomace as a new fiber origin in molded pulp packaging and functional approaches to enhancing water resistance in those packaging materials. Co-authors of the paper are Clara Lang, Jooyeoun Jung, and Taoran Wang.
All of them are former or current members of the Sustainable Food Packaging and Processing team in the Department of Food Science and Technology in Oregon State’s College of Agricultural Sciences.
The research was supported by the Oregon Department of Agriculture Specialty Crop Block Grant Program. Kerr Concentrates, Inc. of Salem and Hood River Juice Company of Hood River provided fruit pomace for the research.