The study, carried out by researchers Cláudia Passos and Sílvia Petronilho from the University of Aveiro's Department of Chemistry, focuses on valorising a waste product "produced on a large scale by the industry" that is typically discarded without further use.

The researchers demonstrated that spent coffee grounds "can be repurposed to create sustainable food emulsions capable of protecting coffee oil from oxidation and preserving its aroma."

According to the text published on the University's website, the research focused on extracting and utilising the oil found in the spent grounds themselves, as well as antioxidant compounds and polysaccharides—substances that are usually discarded after the beverage is prepared.

After the oil was extracted, the defatted grounds were used to obtain polysaccharide-rich extracts via microwave-assisted extraction.

Two extracts were obtained: one at 150°C (designated MW1Sn) and another at 180°C (designated MW2Sn); both consisted primarily of galactomannans and arabinogalactans.

The MW1_Sn extract stood out for exhibiting higher levels of chlorogenic acids, compounds associated with antioxidant properties.

“Using these extracts, the researchers developed water-in-oil-in-water emulsions—structures used to encapsulate and protect compounds susceptible to oxidation,” the text describes, adding that “the emulsions created demonstrated good stability and maintained their structural integrity.”

“Beyond stability, the results showed that these emulsions helped preserve compounds responsible for coffee’s characteristic aroma, such as furans, while limiting the release of markers associated with lipid oxidation, such as aldehydes, which can cause undesirable odours and flavours,” it reports.

Overall, the study “demonstrates the feasibility of repurposing coffee grounds to produce food emulsions that are stable and effective at protecting the aroma of coffee oil.”

According to the University of Aveiro, “the study’s results pave the way for the development of new, sustainable, and circular-based food applications, reducing waste from a highly abundant global by-product.”