Photo by University of British Columbia
A new compostable bioplastic for use in coffee pods represents another step forward in the production of truly green pods.
The material for the new biodegradable pods was developed by researchers at the University of British Columbia. According to the researchers, pods made of the material also keep the coffee inside fresher than other compostable pods.
Pods used for making single serve cups of coffee have been around since the mid-1980s, with early models made from petroleum-based plastics. According to the National Coffee Association’s National Coffee Data Trends survey conducted in January 2020, single-serve coffee pods were the second most popular preparation method and are used by 27 per cent of coffee drinkers. This is up from 19 per cent in 2012 but down from a peak of 29 per cent in 2017 of all coffee consumed.
Single serve pods traditionally consisted of a container made of plastic lined with aluminum and other materials. Since their first introduction in the 1980s, they became a huge environmental problem with some reports suggesting the number of pods that have been used, placed end-to-end, would encircle the Earth 11 times.
Several coffee companies now use compostable coffee pods to help alleviate the problem. But compostable coffee pods aren’t perfect, according to Zac Hudson, assistant professor of chemistry at UBC and developer of the new bioplastic.
“Existing solutions either lack a really good barrier to oxygen and moisture—so that the coffee goes stale, or (they) still contain a lot of non-biodegradable petroleum products that just break down to microplastic,” he said.
How they did it
Photo by University of British Columbia.
His goal was to design a product that led to a fresh tasting brew, could hold the same volume of coffee grounds as other pods, would keep the coffee fresh for longer, and be fully compostable.
The coffee pods he and his team developed have two key components. First is an outer shell made from bamboo fibre which gives structural reinforcement and allows the lining to be extra thin. The inner bioplastic capsule is designed to break down into carbon dioxide, water and organic biomass.
The bioplastic material is made predominantly from polylactic acid (PLA) which is compounded with other plant-based materials and minerals to give the needed heat-resistance and rigidity to avoid deformation when the coffee is made. The PLA usually comes from corn but “can be made from any kind of starch-based thing—like potatoes, or rice,” he said.
No adhesives or glues are used in the manufacturing of the pods to avoid petroleum-based products. Instead, the materials are fused together using ultrasonic welding techniques. The resultant pods are fully compostable and can be sent to municipal compost facilities, Hudson said.
The pods make their market debut this month with B.C.’s Xoma Superfoods where, full of coffee, they can be ordered online. Eventually, the pods will be available to other coffee companies.
There’s always a ‘but’
However, they are not appropriate for backyard compost bins.
“Backyard composting in Canada is actually pretty difficult, because for much of the year Canada is very cold, and composting is very inactive when it’s cold. But in municipal composting, depending on the technique they use, they control the environment inside there, and that allows the pods to break down,” he said.
According to Trevor Charles, professor of biology at the University of Guelph, PLA is not an uncommon material in bioplastics. He concurs that many biodegradable plastics on the market don’t degrade very well and are not backyard compostable
“In order to degrade them really well, they need to go through industrial composting. A challenge there is most times it’s not diverted to the correct industrial composting process. That has to be available in the municipality. They have to have some type of green bin setup and it can cause problems,” he said.
Dr. Trevor’s own work in the area is using bacteria to produce bioplastic materials. His team is working with lactose waste from the dairy industry. This is fed to specialized bacteria which digest it then convert it to the desired bioplastic.
All food containers could theoretically be made using truly compostable bioplastics, but right now it’s too pricy for most producers to consider. “The main limitation is the cost of production. Traditional plastics are so cheap to produce. We could easily replace all of them with degradable plastic, but it’s going to cost,” he said.