Extraction of Oil from Spent Grounds Coffee using Ultrasound as Pre-Extraction Method

The treatment and processing of coffee annually produces a large volume of biological waste, which contributes to environmental pollution, it is estimated that coffee production generates approx. 6 million tonnes of spent coffee grounds per year in the world (GETACHEW and CHUN, 2017). Thus, the sludge becomes a residue equivalent to approximately 50% of the roasted coffee in the soluble coffee industry (PUJOL D. et al. 2013). The major problem of the discharge of spent ground coffee in the environment is the presence of caffeine and phenolic compounds when in concentration above 2.5% due to toxicity to plants and soil microorganisms (JANISSEN and HUYNH, 2018). Therefore, this project proposed to extract the oil from the coffee grounds using the ultrasound method as a pre-extraction method to the soxlet extractor, aiming at eliminating the environmental contamination of the residue and at the same time adding value through the study of the oil for use in cosmetics due to the high amounts of phenolic compounds and antioxidants. The results showed that the application of the ultrasound as a pre-extractive method during 30 min allowed to increase the oil quantity by 70% in relation to the use of the soxlet extractor only, maintaining the quality of the composition.