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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