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The research explored the chemical characteristics of essential oils (EOs) extracted from the peels of four citrus fruits grown in northeastern Peru (lime, sweet lemon, mandarin and orange). The essential oils were extracted by hydrodistillation using a green solvent, and subsequently, their physicochemical profile, bioactive, heat capacity, and RAMAN mapping were determined; in addition, the volatile composition was determined by gas chromatography (GC-MS), and the main phenols by liquid chromatography (UHPLC). The results evidenced that sweet lemon and mandarin essential oils had higher antioxidant activity (1592.38 and 1216.13 μmol TE/g) and total phenolic content (680.78 and 420.28 mg GAE/g). In contrast, sweet lemon peel essential oil had the highest total flavonoid content (23.18 mg QE/g). D-limonene was the most abundant aromatic compound in orange (>67 %), mandarin (>70 %), and sweet lemon (>72 %) EOs; however, in the lime, it was the lowest (37 %). The most abundant component was the cyclobutane, 1,2-bis(1-methylethylethylenyl)-, trans- (32 %).

Revaluing agri-food waste to offer consumers bioactive compounds for a healthy diet is an important issue. In the present work, the antioxidant capacity (AC), total phenolic content (TPC) and phenolic compounds of pulp and bagasse of four Peruvian berries with UHPLC-DAD was determined. Elderberry (Sambucus peruviana Kunth) bagasse had a greater amount of TPC (4.87 ± 0.02 mg GAE/100 gfw) and AC (7.66 ± 0.04 and 7.51 ± 0.24 μmol TE/gfw in DPPH and ABTS, respectively) than the bagasse of the other berries, with a strong positive correlation between TPC and AC. Blueberry (Vaccinium floribundum Kunth) bagasse contains the highest amount of gallic acid (103.26 ± 1.59 μg/gfw), chlorogenic acid (1276.55 ± 1.86 μg/gfw), caffeic acid (144.46 ± 1.78 μg/gfw), epicatechin (1113.88 ± 1.82 μg/gfw) and p-coumaric acid (77.82 ± 1.92 μg/gfw). Elderberry (Sambucus peruviana Kunth) bagasse contains the highest amount of catechin (153.32 ± 0.79 μg/gfw). No significant differences were found in the content of chlorogenic acid and epicatechin of blackberry (Rubus roseus Poir). It was shown that the wastes of the four Amazonian berries have higher values of bioactive properties than their pulp, being the elderberry bagasse the one with the best properties.