Only 30% of a coffee bean is soluble in water, and many brewing methods aim to extract significantly less than that. So of the Americans consume in a year, more than 1.1 billion pounds of grounds are knocked from filters into compost bins and garbage cans.

While watching the grounds from her own espresso machine accumulate, , a 91̽�� doctoral student in human centered design and engineering, saw an opportunity. Coffee is nutrient-rich and sterilized during brewing, so it’s ideal for growing fungus, which, before it sprouts into mushrooms, forms a “mycelial skin.” This skin, a sort of white root system, can bind loose substances together and create a tough, water-resistant, lightweight material.

Luo and a 91̽��team developed a new system for turning those coffee grounds into a paste, which they use to 3D print objects: packing materials, pieces of a vase, a small statue. They inoculate the paste with Reishi mushroom spores, which grow on the objects to form that mycelial skin. The skin turns the coffee grounds — even when formed into complex shapes — into a resilient, fully compostable alternative to plastics. For intricate designs, the mycelium fuses separately printed pieces together to form a single object.

Jan. 23 in 3D Printing and Additive Manufacturing.

“We’re especially interested in creating systems for people like small businesses owners producing small-batch products — for example, small, delicate glassware that needs resilient packaging to ship,” said lead author Luo. “So we’ve been working on new material recipes that can replace things like Styrofoam with something more sustainable and that can be easily customized for small-scale production.”

To create the “Mycofluid” paste, Luo mixed used coffee grounds with brown rice flour, Reishi mushroom spores, xanthan gum (a common food binder found in ice creams and salad dressings) and water. Luo also built a new 3D printer head for the that the UW’s Machine Agency lab designed. The new printer system can hold up to a liter of the paste.

The team printed various objects with the Mycofluid: packaging for a small glass, three pieces of a vase, two halves of a and a two-piece coffin the size of a butterfly. The objects then sat covered in a plastic tub for 10 days, during which the mycelium formed a sort of shell around the Mycofluid. In the case of the statue and vase, the separate pieces also fused together.

The process is the same as that of homegrown mushroom kits: Keep the mycelium moist as it grows from a nutrient rich material. If the pieces stayed in the tub longer, actual mushrooms would sprout from the objects, but instead they’re removed after the white mycelial skin has formed. Researchers then dried the pieces for 24 hours, which halts the fruiting of the mushrooms.

The finished material is heavier than Styrofoam — closer to the density of cardboard or charcoal. After an hour in contact with water, it absorbed only 7% more weight in water and dried to close its initial weight while keeping its shape. It was as strong and tough as and expanded polystyrene foam, the substance used to make Styrofoam.

Though the team didn’t specifically test the material’s compostability, all its components are compostable (and, in fact, edible, though less than appetizing).

Because the Mycofluid requires relatively homogeneous used coffee grounds, working with it at significant scale would prove difficult, but the team is interested in other forms of recycled materials that might form similar biopastes.

“We’re interested in expanding this to other bio-derived materials, such as other forms of food waste,” Luo said. “We want to broadly support this kind of flexible development, not just to provide one solution to this major problem of plastic waste.”

, a 91̽��master’s student in human centered design and engineering when completing this research, is a co-author, and , 91̽��associate professor of human centered design and engineering, is the senior author. This research was funded by the National Science Foundation.

For more information, contact Luo at danlil@uw.edu.

Many people remember a specific food they enjoyed as children, whether it’s a special pie made by a grandparent, a once-a-year tasty treat for a holiday or spring rolls from a street vendor. But while the memory of the experience is readily available, the recipe to make that food is not. Even with access to recipes online or passed down through generations, it’s hard to balance the complicated process of cooking with the sensory details from a memory.

What if we could use technology to take some of the pain out of re-creating recipes? Maybe a thermometer to keep tabs on the temperature or a stirrer to continuously mix ingredients? That way, a cook could focus all of their attention on the details in their memories: the taste, the texture or the smell.

, a 91̽�� doctoral student of human centered design and engineering, developed a toolkit of sensors and controllers that helped her re-create three dishes from growing up in China: rice wine, tofu and spring roll wrappers.

Luo April 25 at the ACM CHI Conference on Human Factors in Computing Systems. , 91̽��associate professor of human centered design and engineering, and , 91̽��assistant professor of human centered design and engineering, are also co-authors on this paper.

91̽��News sat down with Luo to talk about this research.

What inspired you to do this project?

Danli Luo: It all started when my advisers and I were brainstorming scents and spices. There’s a very special spice, called litsea oil, that I don’t think is common in Western culinary tradition or even in Asian culinary tradition. It’s very specific to a region that my parents are from, thousands of miles away from here. So the inspiration for this project was to develop a toolkit that could help us re-create culturally meaningful dishes — all three of the dishes I made for this paper used different spices from my childhood. I had to dig around the internet quite a lot to find the litsea oil. And it’s still a bit different than what’s in my memory.

Why do the foods have to be personally significant to use this method?

DL: If you haven’t tried a dish ever, how can you re-create a personal experience from it? This toolkit works more with something that you have eaten but never made before — such an ancestor’s recipe — and you just can’t figure out the process.

The toolkit helps us simplify that process. And then we use our memory to gauge the final product. During the process of re-creating these dishes, we can extract the joy and the connection to our family and loved ones.

How does your toolkit compare to other “precision cooking” techniques, such as an Instant Pot or a bread maker?

DL: Instant Pot is a great tool, but it automates everything. If something goes wrong, you won’t understand what happened. You just have to do it again, and you still don’t know why or how things went wrong because you are not part of the experience. And most of the time I don’t think people have agency over the recipe that they’re going to try.

We want to celebrate the cooking effort, that connection, that ritual of eating together with family and friends. So it’s not like we want a toolkit that just takes care of the cooking for us. We would love to see people enjoying cooking with a little help from the tool to make the cooking process less complicated.

So how does the toolkit work?

DL: The toolkit comes in after a period of trial and error. We find that there are certain things that we can quantify or digitize.

When people from my hometown are making the kinds of food we made for this paper, they don’t use a thermometer or a precision oven. They still use older techniques that have been perfected over centuries. But if you were to move this whole setup to another place, everything changes — for example, the humidity is different, crops have different protein content and water has different alkalinity.

There are so many reasons why a recipe might not work, and having a toolkit helps people with that. It can alleviate some of the pain by automating things such as temperature control so that you can focus on the flavor, on the chemical reaction, on the changes between molecules.

We wanted to elevate people’s sensitivity during the process of cooking with some degree of help from simple automation.

In your paper, you said the first time you tried to make the rice wine, it turned out to be vinegar. Tell us about the process.

DL: For the rice wine, I found this database online where people have written scientific papers about wine fermentation. So I followed their conditions, but it just didn’t turn out. Then I had to debug. The problem wasn’t with the thermometer I was using. I had to figure out other environmental factors that we didn’t predict.

In this case, I didn’t take into account that the chemical reaction of the rice and yeast mixture could change the temperature. The change was so slight that the thermometer didn’t detect it and adjust accordingly. I changed the temperature of the water bath that the reaction was sitting in to finally successfully make rice wine instead of vinegar.

How did it feel to make and then eat these foods from your childhood?

DL: I think cooking is a process that should be enjoyed and celebrated. For example, when I made the tofu, watching it curdle up was part of the fun. You can see how the chemical reaction happens instantaneously. That’s really enjoyable for me. And that’s an experience we wanted to pass along. You can buy packaged tofu from the supermarket and it tastes OK. But the fun of making it is an irreplaceable experience.

When I tasted the flour skin spring roll, it brought me back to when I was a kid in my father’s hometown. This is street food. It’s in a market and we would walk around and eat it together. It’s a great memory.

This research was funded by the National Science Foundation.

For more information, contact Luo at danlil@uw.edu.

Grant numbers: 2029249 and 2222242