Debittering of Washington naval and Valencia orange juices by adsorption resins and effects on the product quality

The purpose of this thesis was to remove compounds contributing to the bitterness of Washington navel and Valencia orange juices by using adsorption resins. The performances of Seplite LSF904 (Sunresin) and Alimentech P-945 (Bucher) resins on debittering of orange juices were first determined. The changes in the quality characteristics of the juices were then evaluated after debittering in an adsorption column with various flow rates (25 mL/min, 75 mL/min and 200 mL/min). The adsorption resins were found to be capable of removing limonin, naringin and hesperidin from Washington navel and Valencia orange juices. Alimentech P-945 (Bucher) resin removed higher amounts of limonin, naringin and hesperidin than Seplite LSF904 (Sunresin) at the lowest flow rate (25 mL/min). The amounts of citric, malic and ascorbic acids in the orange juices were found to decrease during debittering depending on the resin type and flow rate of orange juices. Debittering however did not cause any significant change in the sugar contents of the orange juices. A decrease in titratable acidity hence an increase in pH values was observed. Debittering was also found to decrease hydroxymethyl furfural (HMF) contents of the orange juices. HMF levels in the orange juices debittered by Seplite LSF904 (Sunresin) were lower than those in the orange juices debittered by AlimentechP-945 (Bucher).