Removal of limonin bitterness by using of some resins in "Washington" orange juices

ABSTRACTPh.D. THESISREMOVAL OF LIMONIN BITTERNESS BY USING OFSOME RESINS IN ?WASHINGTON? ORANGE JUICESOsman KOLADEPARTMENT OF FOOD ENGINEERINGINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF ÇUKUROVASupervisor : Prof. Dr. Ali ALTANYear: 2005, Pages: 201Jury : Prof. Dr. Ali ALTAN: Prof. Dr. Ahmet CANBAŞ: Prof. Dr. Seyhan TÜKEL: Prof. Dr. Hasan FENERCİOĞLU: Prof. Dr. Nevzat ARTIKBitterness due to limonin (delayed bitterness) in citrus juices especiallyorange juices has become an increasingly important economic problem. Limonin isknown as the main bitter component which can strongly affect the organolepticproperties and determine the consumer?s acceptance of orange juices.Excessive bitterness in the orange juices processed from early and midseason Washington navel orange (Citrus sinensis L. Osbeck) results from thedevelopment limonin from its precursor, limonoate A-ring lactone, found primarilyin the tissues of the fruit. When pressing oranges, the nonbitter limonoate A-ringlactone contained in the orange tissues passes into the liquid phase where it isconverted to limonin (Limonin A, D dilacton) in process accelerated by asitic pH ofthe juice and also by heat.In this study, the selective removal of limonin bitterness from Washingtonnavel orange juice by batch adsorption to the ?Amberlite XAD-16HP? and ?DowexOptipore L285? was investigated and the determination of some compositionalchanges that occurred with orange juices debittering using adsorption resins were theprimary focus.?Amberlite XAD-16HP? and ?Dowex Optipore L285? have been successfullyused to reduce bitterness to acceptable levels in Washington navel orange juices.Average limonin concentrations were reduced 97-10% with ?Amberlite XAD-16HP?, 95-99% with ?Dowex Optipore L285?.Key Words : Limonin, Orange, Washington navel, Debittering, AdsorbentII