Sorption of citrus flavour compounds on XAD-7HP resin during the debittering of grapefruit juice

P>Grapefruit juice made from concentrate was debittered using a laboratory-scale downflow column packed with XAD-7HP adsorbent resin. Sorption of the bitter principle naringin was analysed by high-performance liquid chromatography. In addition, the influence of the debittering process on the flavour of the juice was investigated using headspace gas chromatography for the volatile flavour compounds alpha-pinene, beta-myrcene, d-limonene, alpha-terpineol and beta-caryophyllene. Kinetic constants were determined for all substances using the Lagergren adsorption model. The debittered juices showed a selective shift in their reduced flavour profile. Reduction of naringin to 51.28% of its initial value led to a decrease in alpha-terpineol to 43.05%, whereas the other flavour compounds ranged from 76.27% (beta-myrcene) to 92.76% (beta-caryophyllene). The column flow rate influenced the adsorption of alpha-terpineol and naringin. The highest affinity for adsorption was consistently observed for the off-flavour alpha-terpineol, which indicates a promising option for its selective removal from processed juices during debittering.