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Determination of Flavonoid Compounds in Dry Orange Pomace by High Performance Liquid Chromatography Coupled with Diode Array Detection
A group of polyphenols called flavonoids, which are abundant in a variety of fruits, vegetables, and medicinal plants, have gained increasing interest due to their antioxidant properties. Flavonoids are rich in fruit juices, of which orange juice has a largescale production. However, this juicing process produces tons of waste each year in the form of orange pomace, in which flavonoids are still present in a large amount. In this project, the major citrus flavonoids, naringin and hesperidin, were extracted from dry orange pomace samples of Ctirus sinensis over pure ethanol using the Soxhlet technique and analyzed by high performance liquid chromatography coupled with diode array detection. Experimental results showed that 63.2 mg hesperidin/g dry mass is present in Citrus sinensis pomace while naringin was not found in Citrus sinensis. Additionally, limonin which is largely known for its delayed bitterness effect in citrus was also identified on the chromatogram and was below the quantifiable limit of the method. Additional peaks were also observed on the chromatogram, which will require further research of these unidentified analytes. Moreover, orange pomace extract exhibited antioxidant behavior, demonstrated by the increased percent (%) inhibition of DPPH when orange pomace extract was present. Quantitative assessment of OP’s antioxidant activity will be carried out in future work.