Coffee is one of the most popular beverages in the world. In 2020/2021, we consumed around 166.63 million 60 kilogram bags of coffee globally, translating to roughly 10 billion cups of coffee annually. This means a lot of wasted coffee grounds that we just throw away. But what if we turned those grounds into an edible product?

Turning used coffee grounds into useful products “such as cups, fabrics, printing inks and biofuels “ is nothing new. The problem of such conversion is its footprint. Coffee grounds contain liquid, so they need to go through a drying phase, releasing into the atmosphere a considerable amount of CO2 in the process.

Not many have managed to create a delicious edible product. Enter Tetsuji Ishigaki, Japanese scientist and President & CEO of SOI, based in Shizuoka, Japan. Forbes reports that he “recently came up with the idea of using koji, a beneficial mould used to make traditional Japanese fermented foods like soy sauce and sake, to upcycle coffee grounds with no negative environmental impact.“

Ishigaki fermented used coffee grounds with koji and created coffee bars called Coleha. 1 kg of coffee grounds is sufficient for 115 bars that also contain cacao butter to help solidify the Coleha. So far, Ishigaki has managed to create three versions of the bar, ranging from 0 % to 40 % sugar content.

Akiko Katayama reports that Coleha is “unexpectedly delicious. 0% sugar tastes like coffee-flavoured dark chocolate with the slight acidity of high-quality coffee. 10% sugar has a fruity, milky taste. 40% sugar carries a caramel note. They all have a thin, crumbly surface and the inside quickly melts in your mouth with an intense coffee taste.”

The beauty and potential of a coffee bar lie in the uniqueness of speciality coffee. Roasters worldwide are on the lookout for coffees with unique and exotic profiles, resulting in beverages that perceptibly differentiate in aroma and flavour. Arguably, coffee bars like Coleha could be as distinct and diverse as the beverages, with acidity being the prized characteristic instead of bitterness associated with some dark chocolate bars.

Koji produces various enzymes, which convert protein into amino acids. As per his lab results, Ishigaki’s coffee paste contains approximately three times more amino acids than raw coffee beans. According to Ishigaki, these enzymes could be the reason for the rich taste of Coleha. He also found some health benefits, such as a high amount of antioxidants and polyphenols.

The process for Coleha coffee paste is patent-pending, but there is an increasing demand for upcycling across the world. Ishigaki has already received partnership queries from Japanese eco-friendly companies, but he believes Coleha could also spread to other parts of the world.


  • Profil21


    Žiga Povše is a freelance writer, translator and a full-time coffee lover. After after visiting his girlfriend's family farm in Cerrado Mineiro, they opened an online store to sell Brazilian specialty coffee, and he remains an avid reader and a prolific writer.

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