ISOLATION OF XANTHOPHYLLS FROM TAIWANESE ORANGE PEELS AND THEIR EFFECTS ON THE OXIDATION STABILITY OF SOYBEAN OIL

The various xanthophylls present in Taiwanese orange peels were analyzed using liquid chromatography and their effects on the oxidation stability of soybean oil under light storage were determined. A mobile phase of hexane-acetone in different proportions and a mixture of cellulose and diatomaceous earth (1:1) as adsorbent were used to isolate the various pigments in orange peels by open-column chromatography. Each separated band was further analyzed by HPLC to determine the probable purity, and each pigment was identified by spectrum analysis. Results showed that violeoxanthin (and its epimers) was present in largest amount in orange peels, followed by violaxanthin, violaxanthin epimer, neoxanthin, sinesiaxanthin, beta-cryptoxanthin, lutein epoxide and lutein. The antioxidant effectiveness of each pigment towards soybean oil was dependent upon concentration.