COMPARISON OF ANALYTICAL METHODS FOR DETERMINING THE ORANGE CONTENT OF PROCESSED JUICES

Different methods (chemical analysis, comparison of UV spectra, SDS-PA GE and ELISA immunoassay) for determining the orange content of proces sed juices were studied. Characteristic differences were observed betw een fruit parts (albedo, flavedo, juice and pulp) and also between var ieties in chemical composition (polyphenols, betaine, stigmasterin) an d UV spectra. Thus it seems that these parameters may be used for dete ction of non-citrus additives and also the citrus by-products. SDS-PAG E analysis of water soluble proteins and the ELISA assay using antiser a raised in rabbits give only tentative results due to the low specifi city of antigens and presence of other probably non-protein immunoacti ve components.