Supercritical fluid extraction of essential oils from Citrus reticulata peels: optimization and characterization studies

Kinnow (Citrus reticulata) peels consist of innumerable oil glands that are easily separable and very valuable due to their nutrition. Citrus essential oils are rich source of antioxidants and polyphenols and possess antimicrobial activity and thus have a wide range of applications in the food, pharmaceutical, and cosmetic industries. Henceforth, the present study has been focused on the extraction of essential oils by supercritical fluid extraction (SFE) from kinnow peels and their characterization. Statistical optimization technique using response surface methodology (RSM) was applied to obtain the optimum value of process parameters (i.e., temperature, pressure, and time) to maximize the yield, antioxidant activity, and total phenolic content (TPC) of essential oil extract. Maximum extraction yield (1.57%), antioxidant activity (79.94% DPPH reduction), and TPC (41.22 mg GAE/g extract) of essential oil extract were obtained at 43 degrees C, 297 bar, and 120 min. The essential oil extract obtained using SFE was characterized using color, FTIR, and GC-MS analyses which confirmed the desirable color and presence of functional compounds. The essential oil extract obtained can be purified further and used by food or pharmaceutical companies for the development of novel functional foods or nutraceuticals.