Investigation of Antioxidant Properties of Free and Bounded Phenol of Kiwifruit Peel Extract and Its Nanocapsules Properties

Kiwifruit peel extract was extracted using ultrasound bath and probe at 50 and 80% intensities. The extract obtained using ultrasound probe at 80% intensity had the highest extraction efficiency (42.19%). Bath ultrasound (265.88 mg/g) and probe at 80% intensity (298.46 mg/g) had the least and highest amount of free phenolic compound, respectively. Bath ultrasound (265.88 mg/g) and probe at 80% intensity (298.46 mg/g) had the highest amount of free phenolic compound. Acid hydrolysis (55.79 to 63.83 mg / g) was more effective in separating the bounded phenols than alkaline hydrolysis (54.39 to 61.92 mg/g). The antioxidant activity of extracted phenols was measured at 100 to 800 mg/L of concentrations by using two free radical scavenging method (DPPH) and iron reduction assay. Increasing the concentration of phenolic compounds in both free and bounded phenols increased the rate of iron reduction and free radical scavenging of DPPH. The highest antioxidant activity was observed in bounded phenols. A concentration of 800 mg/L of each phenol was used to encapsulation with Lepidiumsativum L. seed gum. The encapsulation efficiency of phenols was 51.96 to 82.36% and the highest efficiency was for phenol bounded sample and acid hydrolyzed ultrasound at 80% intensity. Zeta potential in all samples was negative and the particles were nanometer sized (less than 172.3 nm). The results of this study showed that Lepidiumsativum L. seed gum is a good wall for encapsulation of free and bounded phenols of kiwifruit peel extract and the acid-bound phenolic samples using probe ultrasound at 80 and 50% intensities and also free phenol obtained with bath ultrasound can be used as antioxidant compounds in food products.