Evaluation of Particle Size, Total Flavonoid, and Antioxidant Activity of Onion Peel ( Allium cepa L.) in Different Forms as a Poultry Feed Additive

This study aims to evaluate the particle size, flavonoid content, and antioxidant activity of onion peel in various forms as a poultry feed additive. The material used in this study was onion peel. Particle size was analyzed using laser diffraction to obtain uniform particle size data. Flavonoid content was determined using UV-Vis spectrophotometry to obtain the total flavonoid content in onion peel. Antioxidant activity was tested using the DPPH method with a UV-Vis spectrophotometer to determine the ability of onion peel to scavenge free radicals. The results showed that the particle size of onion peel in powder form was (36.24 μm), solution form (0.98 μm), and extract form (3.47 μm). The highest flavonoid content was found in the powder form (335.97 mg QE/g), followed by the extract form (11.91 mg QE/g), and the solution form (1.66 mg QE/g). The strongest antioxidant activity was demonstrated by the IC 50 value of the extract (1.69 μg/mL), followed by the powder (8.57 μg/mL), and the solution (458.18 μg/mL). It can be concluded that onion peel has the potential to be used as a feed additive, as indicated by its particle size, flavonoid content, and antioxidant activity.