Impact of different drying techniques on grapefruit peels and subsequent optimization of ultrasonic extraction conditions for bioactive compounds

Abstract

AbstractThis research aims to investigate the effect of different drying methods on the phytochemical compounds of grapefruit peels and the subsequent optimization of ultrasonicated assisted extraction conditions for bioactive compounds. Based on the maximum retention of phenolic compounds and naringin content, the hot air‐drying approach was selected for optimization of extraction process. The Box–Behnken design was used for ultrasonic‐assisted extraction (UAE) of bioactive compounds from hot air‐dried peel powder. Three factors such as solvent concentration (SC), ultrasonic amplitude (UA), and sonication time (ST) were considered for optimize the extraction condition based on total phenolic content (TPC), total flavonoid content (TFC), naringin content, and total antioxidant activities (TAA). UV‐spectrophotometric and HPLC was used for the determination in this study. The results revealed that UA and ST had significant effects on all the extraction responses. Based on the numerical optimization, the optimum extraction condition was found to be 48% (v/v) ethanol concentration, 40% ultrasonic amplitude, and 13 min sonication time. The respective optimum phytochemicals and antioxidant activity responses were obtained as TPC (78.5 mg GAE/g dw), TFC (53.5 mg naringin/g dw), naringin content (40.8 mg/g dw), and total antioxidant activities by DPPH assay (25.5 mM Trolox/g dw), ABTS*+ assay (4050 mM Trolox/100 g dw) and FRAP assay (17.45 Fe [II]/g dw).Practical ApplicationsFruit peels are a rich and valuable bioactive residue obtained from the various juice and beverage processing industries. Grapefruit peels are an abundant source of antioxidants and bioflavonoids such as naringin and hesperidin, which have huge potential as a functional ingredients. The optimum extraction condition obtained by this UAE technique has higher levels of polyphenolic compounds and flavonoids, particularly naringin, which shows a wide range of applications in the pharmaceutical sector and might be a way towards its effective sources of utilization in functional foods.