A Comparison of the Levels of Lutein and Zeaxanthin in Corn Germ Oil, Corn Fiber Oil and Corn Kernel Oil

Abstract

All commercial corn oil is obtained by pressing corn germ and/or extracting the germ with hexane. In the current study, six types of corn oil were prepared by extracting corn germ, corn fiber and ground corn, each with hexane or with ethanol. The levels of lutein, zeaxanthin and other carotenoids were quantitatively analyzed in the six corn oils. The levels of lutein + zeaxanthin in the oil ranged from 2.3 lg/g for hexane-extracted corn germ oil to 220.9 lg/g for ethanol-extracted ground corn oil. These results indicate that a diet that includes 30 g (*2 tbsp) per day of the unrefined corn oil obtained by extracting ground corn with ethanol would provide *6 mg of lutein + zeaxanthin, the daily dosage that is currently considered to be necessary to slow the progression of age-related macular degeneration.

The Composition of Crude Corn Oil Recovered after Fermentation via Centrifugation from a Commercial Dry Grind Ethanol Process

“…Lutein and zeaxanthin have been reported to be present in high levels in the macula portion of the retina, and ingesting at least 6 mg of lutein ? zeaxanthin per day has been reported to be an effective dosage to delay the onset of age-related macular degeneration [8]. The levels of lutein and zeaxanthin were very low in the corn germ oil as we reported previously [8].…”

“…Carotenoids were analyzed via a previously reported method [8], employing a LiChrosorb 7 Diol column, 3 9 100 mm (Varian Scientific, Lake City, CA, USA) with an isocratic mobile phase consisting of hexane/isopropanol/acetic acid, 96.9/3.0/0.1, v/v/v, at a flow rate of 0.5 ml/min. HPLC analyses were conducted with an Agilent Model 1100 HPLC equipped with an auto sampler and an Agilent Model 1100 Diode Array Detector to measure the visible absorbance of the carotenoids at 450 nm.…”

“…Corn fiber oil and corn kernel oil contain even higher levels of total phytosterols (*10 and 2%, respectively) [7]. Although commercial corn oil contains very low levels of carotenoids, we recently reported that corn kernel oil obtained by the ethanol extraction of ground corn kernels contains high levels of lutein and zeaxanthin (*100-fold higher than those in commercial corn oil) [7,8].…”

Analysis of carotenoids and vitamin E in selected oilseeds, press cakes and oils

“…There was an almost complete loss of carotenoids during the bleaching with diminishing colour intensity of the oil. Rossi et al [27] made similar statements for palm oil, Su et al [28] did so for olive oil as Moreau et al [29] stated this bleaching induced carotenoid loss for corn oil.…”

“…Regarding the absence of carotenoids in refined oils, previous technological studies have shown that carotenoids are removed from the crude oil by various refining steps [21,[25][26][27][28][29]. The bleaching earth adsorbs the plant pigments, additionally a thermal deterioration happens during the deodorization [25].…”