Deacidification of orange juice by ion exchange resins and its effects on the quality parameters

In this study, deacidification of Valencia orange juice using five different ion exchange resins (Amberlite IRA96, Amberlite FPA53, Amberlite FPA54, Amberlite FPA51 and Lewatit S4528) was evaluated. The differences in the composition of orange juices after deacidification were determined. The most decrease (%56.25) in PME and titratable acidity (%65.80) and the most increase (%23.02) in pH were determined in the juices treated by Amberlite FPA51 resin. The total dry solid content was decreased (%7.71-20.10). The most reduction (%15.43-15.40) in the browning index was established in the juices treated with Amberlite IRA96 and Amberlite FPA51 resins and the greater colour variation (ΔE=4.89) was identified by the treatment of Lewatit S4528 resin. The HMF content was decreased by deacidification. A concentration range of 3.16-4.08 µg/L was determined for HMF in pasteurized orange juices. The ascorbic acid content was decreased as %16.42-26.38 by deacidification. Decreases (%2.39-4.43) and also increases (%1.42-8.18) were assessed in the carotenoid contents of orange juices treated by the resins. The most predominant carotenoid content was established as β-cryptoxanthin and it is followed by β-carotene, xanthophyll, α-carotene and zeaxanthin. The most decrease (%28.41) in total phenolics was assessed by Amberlite FPA54 resin treatment. The amounts of hydroxycinnamic acids (chlorogenic acid, caffeic acid, ferulic acid, p-coumaric acid, o-coumaric acid and cinnamic acid), hydroxybenzoic acids (syringic acid, PAEE (protocatechuic acid ethyl ester), gallic acid and vanillic acid), flavanones (hesperidin, eriocitrin, neoeriocitrin, neohesperidin and naringenin), flavonol (rutin) and flavone (luteolin) were determined in the juices and the decreases in their amounts by resin treatments were identified. The most abundant organic acid in orange juices was assessed as citric acid and it is followed by quinic acid, malic acid, tartaric acid, succinic acid and oxalic acid and significant decreases in organic acids of juices by deacidification were determined. In sensorial evaluation, Lewatit S4528 resin was preferred in terms of acidity, flavor and general acceptance. In terms of colour and smell, Amberlite FPA53 and Amberlite IRA96 resins were preferred, respectively. Key Words: Orange Juice, Deacidification, Ion Exchange Resin Treatments, Organic Acid Compounds, Phenolic and Carotenoid Compounds