Oxidation of ascorbic acid in stored orange juice is associated with reduced plasma vitamin C concentrations and elevated lipid peroxides

Ascorbic acid oxidizes in refrigerated orange juice, but the physiological relevance of this deterioration is unknown. We compared changes in plasma vitamin C and total lipid peroxides (thiobarbituric acid-reactive substances, TBARS) in the 2-hour period following consumption of commercial orange juices on day 1 vs day 8 of storage (4degreesC). The ascorbic acid content decreased significantly after storage in juice reconstituted from frozen concentrate (117 +/- 8 vs 89 +/- 8 mg/8 fl oz, P=.001), but did not change in chilled juice (69 +/- 5 vs 64 +/- 12 mg/8 fl oz.). The mean incremental TBARS value was less on day 1 vs day 8 for juice from frozen concentrate (-0.46 +/- 0.72 and 0.70 +/- 0.53, P=.046), but did not differ for chilled juice (0.00 +/- 0.49 and 0.54 +/- 0.89). The incremental values for plasma TBARS and vitamin C in the 2-hour postprandial period were inversely related (r=-0.48, P=.017). These data indicate that the loss of ascorbic acid in refrigerated juice may impact postprandial oxidative stress.