Electron beam irradiation enhanced extraction and antioxidant activity of active compounds in green walnut husk

Green walnut husk (GWH) contains abundant active compounds and is valued as a potential source of natural antioxidants. This study aimed at assessing the impact of electron beam irradiation (EBI) pretreatment on the extraction yield and antioxidant activity of active compounds in GWH. The ultrasonic extraction of active substances was optimized by response surface method (RSM). Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction revealed physical structure changes in GWH powder. After EBI pretreatment, the content of polyphenols, flavonoids, and triterpenes in GWH increased by 18.88%, 43.00%, and 11.08%, respectively. Irradiation doses up to 30 kGy, DPPH, OH, and ABTS radical scavenging activity and reducing power of the crude extract were enhanced by 9.56%, 15.62%, 15.60%, and 36.98%, respectively. This was significantly different (P < 0.05) than the non-irradiated GWH. Therefore, EBI is a new pretreatment technology with potential application in the extraction and utilization of GWH.