COMPARATIVE STUDY OF THE POSSIBLE METHODS FOR THE QUANTITATIVE DETERMINATION OF PURE ORANGE CONTENT OF JUICES

Abstract

Different methods (chemical analysis, comparison of UV spectra, SDS-PAGE and ELlSA immunoassay) for determining the orange content of processed juices were studied. Char- acteristic differences were observed between fruit parts (albedo, flavedo, juice and pulp) and also between varieties in chemical composition (polyphenols, betaine, stigmasterin) and UV spectra. Thus it seems that these parameters may be used for the detection of non citrus additives and also of citrus by-products. SDS-PAGE analysis of water-soluble proteins and the ELlSA assay using antisera in rabbits give only tentative results due to the low specificity of antigens and the presence of other probably non protein immunoactive components.