Color and carotenoid profile of Spanish Valencia late ultrafrozen orange juices

Twelve ultafrozen orange juices obtained from the variety Valencia late were analysed to characterize the color and the carotenoid profile of this recently developed product. Reflectance color measurements were carried out by spectroradiometry, using a white and a black background. In order to study the carotenoid pigments occurring in the orange juice, HPLC with gradient elution with methanol (MeOH), methyl tert-butyl ether (MTBE) and water as mobile phase was used. Separations were performed on a C30 column. Identification of carotenoids was made by comparison of their spectral and chromatographic characteristics with those corresponding to standards when possible. To help identify the peaks in the chromatograms, aliquots of orange juice extracts were analysed before and after treatment with hydrochloric acid (HCl) and sodium borohydride (NaBH4), to check the presence of 5,6-epoxy-carotenoids on one hand, and, on the other hand, ketocarotenoids or carotenals.