Alternative green solvents for the extraction and separation of specialized metabolites in residues from the productive coffee chain

Abstract

Coffee beans production reached c.a. 10 million tonnes in the 2018/2019 harvest. Brazil is the largest coffee producer, accounting for 30% of the international market, whereas São Paulo state is the third largest Brazilian producer. Many types of coffee-related residues are generated in the whole chain. For example, it is estimated that 6-7 million tonnes of coffee pulp and rusks are generated per year worldwide (240 thousand tonnes just in São Paulo). The water which is employed in humid and semi-humid processes to remove coffee fruit pulp and husks is another example. It is usually discharged directly into the environment without any treatment. Currently applications of coffee-related residues are unappropriated or don't add enough value to the production chain. Thus, addressing efforts to find high-added value applications for these residues is urgent. The exploitation of these residues should be based on green chemistry and sustainable engineering principles, otherwise it would be generating more waste rather than reducing it. To the best of our knowledge green solvents such as natural eutectic solvents (NADES) were applied only to two types of coffee residues and only for the extraction of medium to high-polar metabolites. We identified and gathered twelve different residues around Botucatu city, from farms to a major producer of coffee bean powder. This project aims the development of efficient and green analytical methods for the extraction of polar and especially of nonpolar metabolites from twelve coffee-chain residues. Alternative green solvents including limonene and hydrophobic NADES will be tested together with ultrasound assisted extraction. The most promising compounds will be quantified in the residues by liquid chromatography and gas chromatography both coupled to mass spectrometry. Extraction efficiencies will be measured by proper metrics and compared head-to-head with those reported in literature for similar purposes. (AU)