Can parchment paper go in the compost or in the green bin? The short answer is yes but there are a couple things you should know.
Parchment paper is made up of 97.5% organic matter in the form of cellulose fibers which are biodegradable. The paper is often coated with silicone which will degrade in soil in the presence of water and catalysts like clay minerals. Therefore, parchment paper is compostable.
To dig deeper, let’s explore more about parchment paper, how it is made, and more.
How is parchment paper made
Parchment paper is most often made from wood cellulose fibers. The fibers are compressed to form paper sheets. These sheets are sometimes bleached with chlorine before being soaked in either sulfuric acid or zinc chloride. Soaking the sheets partially dissolves the paper and causes sulfurized compounds to form which gives the paper its heat, grease and water resistance.
After the soaking process, the parchment paper is often coated with non-stick compounds like silicone (more specifically polydimethylsiloxane).
How is parchment paper problematic
The compounds used to make parchment paper have some potential environmental consequences. Here’s a quick explanation of a few.
Cutting trees is part of the process for obtaining the wood fibers needed to make parchment paper. Some companies claim they use “responsibly sourced” wood fibers. But without actually identifying these sources, how can anyone tell if this claim is true or if it’s just greenwashing?
Chlorine is used to bleach the wood fiber paper and turn it from brown to white. The bleaching process can leave chlorine by-products like dioxin in the paper. This compound can get into your food and it is carcinogenic; however the actual levels in the paper are likely to be low.
Still, if you had a choice, it is best to use unbleached parchment paper.
Polydimethylsiloxane is a type of silicone used to coat parchment paper and gives it that non-stick effect.
Silicone is made by combining silicon, oxygen and hydrocarbons, which are most often derived from fossil fuels. The resulting material acts like rubber and plastic and has heat and chemical resistant properties.
By the way, polydimethylsiloxane is used as an anti-foaming agent in skin moisturizers, hair conditioner, pharmaceutical drugs and breast implants. It is also added to some cooking oils.
The list is long and most institutions deem the chemical as safe and even food grade.
But there’s a study that found polydimethylsiloxane ions from silicone coated parchment paper on the bottom surface of freshly baked cookies and pizzas. So, the ions are getting into our food. What happens after that, we don’t quite know yet because there hasn’t been much research on the matter.
What happens to parchment paper in the compost
This 2021 study out of Poland explored the degradation of cooking-oil-polluted parchment paper that had silicone coatings on both sides.
The study showed the parchment paper was still 97.5% organic matter (cellulose) even with the silicone coatings. After six weeks of composting, the paper had almost completely decomposed.
The study did not explain what happened to the silicone coating layer.
One study from Finland showed polydimethylsiloxane breaks down in soil in the presence of water and different clay minerals which act like catalysts.
The compound breaks down into dimethylsilanediol which evaporates into the atmosphere where it is oxidized further. Dimethylsilanediol can also break down in the presence of certain soil bacteria and fungi.
So, bottomline, parchment paper will degrade in the compost as long as there is enough moisture and clays like kaolinite and even bentonite (according to this study).
What is a good alternative to parchment paper?
Butter or oil and flour together are a good alternative to parchment paper. To prevent cakes, cookies, and pastries from sticking to baking trays and bread pans, coat them with butter or oil then sprinkle flour over them.
This is not a perfect method. There will be a couple crumbs from the baked goods and cleaning up will take a tad bit longer. But, you will avoid having polydimethylsiloxane ions in your food. So, that’s a bonus!