Antioxidant - A possible way to valorize citrus peels and seeds, which are byproducts of the juice extraction industry, is to use them as natural antioxidants. The antioxidant activity of several citrus peel and seed extracts obtained either by methanol extraction (free phenolic compounds) or by alkaline hydrolysis (bound phenolic compounds) was tested in a model system based on accelerated citronellal oxidation.

The phenolic composition of some citrus peels and seeds was described for the first time. No clear relationship could be shown between the antioxidant activity and the phenolic composition of the extracts.

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Anti-Inflammatory - Despite the fact that the enhancing effect of heat treatment on the antioxidant activity of citrus fruit peels has been well documented, the impact of heat treatment on citrus peel beneficial activities regarding anti-inflammation is unclear.

To address this issue, we determined the anti-inflammatory activities of heat-treated citrus peel extracts by measuring their inhibitory effect upon NO production by lipopolysaccharide-activated RAW 264.7 macrophages.

Results showed that the anti-inflammatory activity of citrus peel was significantly elevated after 100 °C heat treatment in a time-dependent fashion during a period from 0 to 120 min.

Proper and reasonable heat treatment helped to release nobiletin and tangeretin, which were responsible for the increased anti-inflammatory activity of heat-treated citrus peels.

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Anti-Fungal - The essential oil (EO) isolated by hydro-distillation from the peel of fully matured ripen fruits of Citrus reticulata Blanco were analyzed by GC and GC–MS. Thirty seven different components were identified constituting approximately ≥99% of the oil.

Fungal sporulation was also complete