engleski

NADES-assisted valorisation of orange peel waste by the integrated biorefinery approach

Orange peel waste obtained from orange juice and canned food production present one of the most abounded wastes from the food industry. Yearly 70 Mt of the oranges is produced worldwide among which the peel comprises about 40- 50% of the total orange weight as a leftover which needs to be disposed of as waste. Valorisation of orange peel waste by following the biorefinery concept is usually carried out via several platforms: (1) direct application as animal feed and fertilizer ; (2) the use as a substrate for the production of biofuels, proteins, industrially valuable enzymes, and other biotechnological products (e.g. citric and succinic acid) ; (3) extraction of bioactive compounds (e.g. essential oils, and organic acids), pectin, and enzymes (e.g. pectin methylesterase). Natural deep eutectic solvents (NADESs) – assisted valorisation of orange peel waste fully fits the green biorefinery concept since these solvents are of low cost and are prepared from natural raw materials with 100% atom economy. This research investigates the use of seven NADESs for valorisation of orange peel waste, with the final goal to propose a unique NADES for integrated biorefinery. Initial screening of NADESs revealed the excellent ability of cholinium-based NADES with ethylene glycol as hydrogen bond donor (ChEg50) to serve as a medium for orange peel-catalysed kinetic resolution (hydrolysis) of (R, S)-1-phenylethyl acetate with high enantioselectivity, as well as it’s stabilizing effect on the hydrolytic enzymes. The ChEg50 also showed a satisfactory capacity to extract D-limonene, and excellent capacity to extract polyphenols, and proteins from the peel. Based on the obtained results, the integrated biorefinery of orange peel waste using ChEg50 in a multistep process was performed. Firstly, enantioselective kinetic resolution was performed (step I ; ee = 83.2%, X = 35%), followed by isolation of the product 1-phenylethanol (step II ; h = 82.2%) and extraction of polyphenols (step III ; h = 86.8%) from impoverished medium. Finally, the residual orange peel was analysed for sugar and lignin content, and results revealed the potential of waste peel for the anaerobic co-digestion process. The main bottlenecks and futures perspective of NADES- assisted integrated biorefinery of orange peel waste were outlined through SWOT analysis

Biorefinery ; D-limonene ; Natural deep eutectic solvents ; Orange peel waste ; Pectin methylestrase ; Polyphenols ; (R)-1-phenylethanol ; SWOT analysis

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