Abstract:In order to improve the utilization value of bound phenolics from ‘dekopon’ citrus pulp residue, the ‘dekopon’ citrus pulp residue without free phenolics was used as raw materials. The effects of different solvent extractions on the content of bound phenolics were compared. Subsequently, the singlefactor test and response surface analysis method were used to optimize the alkaline extraction process.And the type and content of monomeric phenol in bound phenolics and free phenolics were detected by HPLC method. The results showed that NaOH solution was the best extraction solvent for the extraction of bound phenolics. At a liquidtomaterial ratio of 22 mL/g, NaOH concentration of 4.1 mol/L,and alkaline hydrolysis time of 3.2 h, the content of bound phenol reached 356.51 mg/100 g. Ten monomeric phenols were detected in the free phenolics extract, among which hesperidin was the highest (284.44 μg/g), and ferulic acid was undetectable. Eight monomeric phenols were detected in the combined phenol extract. The content of naringin dihydrochalcone was the highest (297.29 μg/g) and the content of ferulic acid reached as high as 128.07 μg/g. Chlorogenic acid, protocatechuic acid were undetectable. In summary, the phenolic acid composition of bound phenolics is rich, and the content of phenolic acid is significantly higher than that of free phenolics, especially the ferulic acid content.