Coffee waste: A surprisingly useful resource

I really like coffee. You too? Probably. Many people like coffee. In fact, so many people like coffee that we should think about how to deal with coffee waste (which is also called “spent coffee grounds”). It even seems that public interest in the topic has been rising over the past five years, if we take Google Trends as a proxy for “public interest”:

Search volume for "coffee waste", according to Google Trends.
Search volume for “coffee waste”, according to Google Trends.

And here are some numbers according to bio bean, a coffee waste innovator:

Around 381,000 tonnes of ground coffee are brewed every year, resulting in an estimated 500,000 tonnes of wet, waste coffee grounds.

from “the significant value of spent coffee grounds”, an article by bio bean.

If you weigh this out in cruise ships, this is more than twice the weight of the Symphony of the Seas, one of the biggest cruise ships in the world!

The Symphony of the Seas. You need more than two of it, if you want to weigh out the coffee waste (spent coffee grounds) produced worldwide in one year. Image from Wikipedia.
The Symphony of the Seas. You need more than two of it, if you want to weigh out the coffee waste (spent coffee grounds) produced worldwide in one year. Image from Wikipedia.

(In another article, on e-waste recycling technologies, I already used the Symphony of the Seas as my standard weight.)

What can we do with coffee waste then, besides using it as landfill?

I tried to do my very modest part, and used my spent coffee grounds in the garden. It is supposed to shy away snails from herbs. It didn’t work.

So I looked for things that might actually work, and did some research with Mergeflow’s tech discovery software. Here is what I found:

Research activity on spent coffee grounds is rising

Among the first things I noticed was that research on spent coffee grounds has been rising over the past five years, even though the overall volume is still very moderate:

Research on spent coffee grounds is rising, as seen in Mergeflow's Science Publications data set.
Research on spent coffee grounds is rising, as seen in Mergeflow’s Science Publications data set.

This rise in R&D activity seems to be mirroring the rise in public interest, as seen in the Google Trends graph above.

The number of R&D publications over the past five years is still small; 400 papers in total. But still, I didn’t want to read 400 papers. In such cases, I usually do two things in order to get a first useful approximation:

  1. Scan the titles and teasers of the most recent three to five papers. I also check the publication dates, in order to get an impression of the topic’s activity rate.
  2. Use one of Mergeflow’s entity type analytics tools. This could be patent classes (which Mergeflow also provides for non-patents), materials, people, organizations, or some other entity type. It depends on the topic which one I select. Then, I look at a tag cloud of the 20 – 40 or so most frequent entities, and zoom in on those that I find interesting or surprising.

Let’s start with what I found interesting in the most recent papers (“most recent” as of 15 July 2020).

Turning coffee waste into biocatalysts and biopolymers

The first paper was on turning coffee waste into biocatalysts and biopolymers:

A review on valorization of spent coffee grounds (SCG) towards biopolymers and biocatalysts production

Biocatalysts, or enzymes, help you increase the rate of a chemical reaction. Washing detergents use enzymes to break down proteins or fat stains, for example. And from biopolymers, you can make packaging, wound care materials, and many other things. For example, the polysaccharides in spent coffee grounds could be used for making biopolymeric films. Here is the paper that describes this:

Polysaccharide-rich fraction of spent coffee grounds as promising biomaterial for films fabrication

Making biofuels from coffee waste

Perhaps some of the biofuel in these railcars was made from coffee waste. Image from Wikipedia.
Perhaps some of the biofuel in these railcars was made from coffee waste. Image from Wikipedia.

Next up in the most recent papers was how to make biofuels from coffee waste:

Added-value molecules recovery and biofuels production from spent coffee grounds

Then, I zoomed out from R&D publications to also include news and blogs. In blogs, I came across research from Lancaster University on how to simplify the “coffee waste to biofuel process”. This process simplification could make biofuel from coffee waste a lot more commercially viable:

A better way of converting coffee waste to biofuel?

Spent coffee grounds as UV-B protection

Next, after going through the most recent papers, I used one of Mergeflow’s entity detection tools. In this case, the one that detects names of chemical compounds. Ethanol was a relatively frequently mentioned compound. Using Mergeflow’s network graph tool, I saw that there is a connection with reactive oxygen species:

Ethanol is a frequently mentioned compound in R&D papers on coffee waste. Reactive oxygen species (ROS) often occurred in the same context, as shown by Mergeflow's network graph tool.
Ethanol is a frequently mentioned compound in R&D papers on coffee waste. Reactive oxygen species (ROS) often occurred in the same context, as shown by Mergeflow’s network graph tool.

Here is one of the papers behind this “ethanol-ROS connection”:

Topical application of spent coffee ground extracts protects skin from ultraviolet B-induced photoaging in hairless mice

For the paper, they used oil and ethanol extracted from spent coffee grounds. When applied topically, it inhibited UVB-induced increase in reactive oxygen species.

Coffee waste extracts could be used to block UVB rays from entering the skin. If UVB rays enter the skin, they induce an increase in reactive oxygen species (ROS). Image from nutritionaction.com.
Coffee waste extracts could be used to block UVB rays from entering the skin. When UVB rays enter the skin, they induce an increase in reactive oxygen species (ROS). ROS in turn has been shown to to cellular damage, and it is hypothesized to play a critical role in aging. Image from nutritionaction.com.

Now, since this is about skin care, we have a good transition to the next finding: cosmetics from coffee waste.

Cosmetics, nutraceuticals, and functional foods from coffee waste

Meet Kaffe Bueno. Kaffe Bueno is a biotech company from Copenhagen, Denmark. They collect spent coffee grounds from hotels, offices, companies, etc., and turn it into various health and skincare products.

Kaffe Bueno's process for turning coffee waste into health and skincare products. Image from Kaffe Bueno.
Kaffe Bueno’s process for turning coffee waste into health and skincare products. Image from Kaffe Bueno.

Currently, Kaffe Bueno has three product lines: An oil for sun care, hair care, and wound healing; a gluten-free flour; and a cosmetic fiber for scrubs, masks, soaps, and cleansers. Kaffe Bueno works with Givaudan, and jointly they launched the coffee oil as a new product.

Making car parts out of coffee chaff

Now let’s move on to something completely different. Car parts, from coffee waste. First, this is not from spent coffee grounds but from coffee chaff. Spent coffee grounds are what remains when you make coffee. By contrast, coffee chaff is a byproduct of roasting beans. It is the skin of the beans that comes off during roasting.

Ford and McDonald’s have teamed up to make car parts from coffee chaff, reported by digitaltrends.com. McDonald’s has the coffee chaff, and Ford makes car parts from it.

A car part made from coffee chaff, in a collaboration of Ford and McDonald's. Image from digitaltrends.com.
A car part made from coffee chaff, in a collaboration of Ford and McDonald’s. Image from digitaltrends.com.

Who knows, perhaps the coffee cup holder in your car is made from coffee chaff as well?

Using coffee waste to remove lead and mercury from contaminated water

Back to spent coffee grounds. It turns out that spent coffee grounds can act as water purifier. They can remove lead and mercury from contaminated water. Researchers at the University of Genoa made a bioelastomeric foam that consists of spent coffee grounds and silicone elastomer:

Spent Coffee Bioelastomeric Composite Foams for the Removal of Pb2+ and Hg2+ from Water

Coffee waste embedded in a silicone elastomer foam can remove lead (Pb+2) and mercury (Hg+2) from contaminated water. Image from ACS.
Coffee waste embedded in a silicone elastomer foam can remove lead (Pb+2) and mercury (Hg+2) from contaminated water. Image from ACS.

Construction materials from spent coffee grounds

Some day you may be traveling on a road made from coffee waste. Image by Joshua Hibbert.
Some day you may be traveling on a road made from coffee waste. Image by Joshua Hibbert.

A road from coffee waste? Yes. Researchers from Swinburne University of Technology in Melbourne have made cement for road construction. This cement consists of steel byproducts, combustion of coal, and spent coffee grounds.


Featured image by Sahand Hoseini.

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