Stability of ascorbic acid in commercially available orange juices.
Johnston CS, Bowling DL
Department of Nutrition, Arizona State University East, Mesa 85212, USA.
OBJECTIVE: To compare the vitamin C content of reconstituted frozen orange juice concentrates at preparation to that of ready-to-drink orange juices purchased 4 to 5 weeks from expiration.
DESIGN: Juices were unsealed and analyzed for reduced and oxidized vitamin C content at the time of purchase and reanalyzed 3 times weekly for 4 to 5 weeks. Same-lot samples of the ready-to-drink juices remained sealed after purchase and were opened for analyses at 3, 2, 1, or 0 weeks before expiration.
SAMPLES/SETTING: Orange juices were reconstituted frozen concentrates, ready-to-drink juice packaged in resealable, screw-top containers, or ready-to-drink juice packaged in nonresealable containers. Juices were obtained from local retailers and stored at 4 degrees C in their original containers when appropriate.
STATISTICAL ANALYSES PERFORMED: The reduced vitamin C content of juices analyzed repeatedly, 3 times weekly for 4 weeks, were compared using repeated measures analysis of variance. Linear regression lines were computed for reduced vitamin C in each juice over time, and differences between slopes were analyzed by oneway analysis of variance.
RESULTS: The orange juices from frozen concentrates contained 86 mg reduced vitamin C per fluid cup at initial preparation and 39 to 46 mg/c after 4 weeks of storage.
Ready-to-drink juices averaged significantly lower reduced vitamin C: 27 to 65 mg/c at opening and 0 to 25 mg/c at expiration 4 weeks later. Ready-to-drink orange juices had twofold to threefold higher concentrations of oxidized vitamin C vs the orange juices reconstituted from frozen, and the decomposition rate of reduced vitamin C was similar for all juices, about 2% per day once opened.
APPLICATIONS: Ready-to-drink orange juices should be purchased 3 to 4 weeks before expiration date and consumed within 1 week of opening.
J Am Diet Assoc 2002 Apr;102(4):525-9
PMID: 11985409, UI: 21980980
Ann's NOTE: Or you can buy a manual or electric citrus juicer and using ORGANIC oranges, create a delicious drink. (DRINK it right away though).
LINK to Florida-owned, Florida-grown organic orange farm, order fruit, order juice, find recipes
Realage.com, posted May 2010
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