Valorization of hazelnut, coffee and grape wastes through supercritical fluid extraction of triglycerides and polyphenols

•Triglycerides were extracted from waste hazelnuts, spent ground coffee, grape seeds.•Polyphenols were extracted from grape skins and seeds in presence of a cosolvent.•Satisfactory extraction yields were obtained at 500 bar and 60 °C for triglycerides.•Phenolic extraction was not affected by cosolvent amounts higher than 5%.•Fractionated recovery of triglycerides and polyphenols from grape seeds is possible.

Triglycerides and/or polyphenols have been extracted through supercritical CO2 from waste hazelnuts (bug-damaged nuts, rotten nuts and damaged roasted nuts), spent ground coffee, grape skins and grape seeds to achieve the valorization of food wastes with a clean and property-preserving-of-extracts technique.With respect to soxhlet extractions satisfactory yields (55–100%) were obtained for triglycerides. Grape seeds and spent ground coffee provided the highest yields (85–100%) while hazelnut wastes provided the highest amounts of triglycerides (0.3–0.4 goil/gwaste). Polyphenols were extracted from grape skins and seeds after adding a cosolvent (ethanol). Results showed that phenolic recovery was less efficient (11–25%) and that cosolvent amounts greater than 5% do not significantly affect the extraction yield. Preliminary tests on grape seeds pointed out that a single supercritical treatment can be used for the fractionated recovery of triglycerides and polyhenols by changing the polarity of the solvent during the extraction process through the addition of a cosolvent.

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