Effects of ozone application and hot-air drying on orange peel: moisture diffusion, oil yield, and antioxidant activity

[Display omitted] •Small doses of ozone are sufficient to increase moisture diffusivity on the drying process.•The yield of essential oil increased slightly with pre-treatment with ozone•Ozone application followed by convection drying reduces the level of polyphenols present in orange peels.•The results of this study may be useful for biorefineries. The citrus essential oil (EO) has several industrial applications due to its antioxidant and antifungal properties. However, as the peels are susceptible to microbiological contamination, their by-products may undergo oxidation and reduction of bioactive compounds. For this reason, this work aimed to evaluate the quality of the processed orange peel (albedo + flavedo), obtained after ozone application (for 2 h at 4 μg L−1 and 40 μg L−1) and drying (at 40, 50 and 60 °C). The parameters evaluated in the study include drying kinetics, color, fungal count, pectin, EO yield, and antioxidant activity of the peels. The main results demonstrate an improvement in the drying process, where the use of ozone boosted moisture diffusion. Increased yield of extracted EO and the antioxidant capacity of peels were also described. Overall, this study contributed to a better understanding of how ozone acts on the physical, chemical, and biological parameters of the citrus by-products.