Stability of ascorbic acid

M Gallarate, ME Carlotti, M Trotta, S Bovo. On the stability of ascorbic acid in emulsified systems for topical and cosmetic use. Int J Pharm 188(2) 233 241, 1999. 

Much has been written about the effects of processing, temperature, and storage conditions on the stability of ascorbic acid in citrus juices. On the other hand, little is known about the stability of folic acid under similar conditions. Chen and Cooper (72) studied the effects of temperature and oxygen and ascorbic acid on the thermal degradation of folic acid, and they reported that ascorbic acid increased the stability of the terra-... 

It has been found that glucose, sucrose, casein, albumin, sodium chloride, flour groats, and starch stabilize ascorbic acid (vitamin C).771 The addition of 5% of starch inhibits the decomposition of ascorbic acid.772 Studies on the stability of ascorbic acid, sodium ascorbate, erythorbic acid, and sodium erythorbate showed that some stabilization is observed after the addition of 8% starch.773 It was reported that the interaction is purely physical in nature.774... 

The stability of ascorbic acid in TPN solutions, neat and in the presence of a fat emulsion has been studied and produced unclear results. Ascorbic acid s stability has been shown to be strongly effected by the oxygen content of the solution, presence of copper, and composition of the amino acid injection used (97). 

Allwood MC. Factors influencing the stability of ascorbic acid in total parenteral nutrition infusions. J Clin Hosp Pharm 1984 9 75-85. 

Bandelin FJ, Tuschhoff JV. The stability of ascorbic acid in various liquid media. / Am Pharm Assoc (Sci) 1955 44 241—244. 

Prompt stabilization of ascorbic acid is especially important in the case of plasma or serum samples. Metaphosphoric acid is often used for this purpose because it also serves as a protein precipitant. Such properties are desirable in the inactivation of oxidase and the catalytic eflFect of copper. Oxalic acid is an attractive stabilizer for ascorbic acid analysis because of its lower cost and greater stability however, it is not a protein precipitant, therefore, it has a limited use for the extraction of animal tissues. The use of ethylenediaminetetraacetic acid (EDTA) in addition to the metaphosphoric acid has been recommended (96). EDTA would chelate divalent cations, and a study has shown it will stabilize ascorbic acid in the presence of copper for several days (96). Perchloric acid has been used also but because of its inherent dangerous properties its use is generally avoided. Trichloroacetic acid and EDTA also seem appropriate extractants for ascorbate in plant materials (97). 

To determine the stability of ascorbic acid under the various concentrations of citrate buffer and pH, the following experiment was performed with the use of a double wavelength, double beam, spectrophotometer (Perkin-Elmer 557). 

The decomposition of ascorbic acid is catalyzed by trace metal ions in solution, hence the addition of sequestering agents such as EDTA and its salts has been shown to enhance the stability of ascorbic acid (291,292,293),... 

The stability of ascorbic acid is influenced by atmospheric oxygen, water activity, oxidative enzymes, pasteurization methods, metal contamination, and sulfur dioxide content. 

Vemuri S, Taracatac C, Skluzacek R. Color stability of ascorbic acid tablets measured by a tristimulus colorimeter. Drug Dev Ind Pharm 1985 11 207-222. 

GEE M (1979), Stability of ascorbic acid, thiamine and /3-carotene in some low temperature dried vegetables , Lebensm-Wiss u-Technol, 12, 147-149. 

R. Yamamoto and S. Kawai, Studies on the stability of dry preparations. VII. Relation between atmospheric humidity and the stability of ascorbic acid, sodium ascorbate, and their diluted preparations [in Japanese],... 

Esteve, M.J., Farre, R., and Frigola, A. 1996. Stability of ascorbic acid in orange juice after initial use at home begins. J. Food Qual. 19, 243-249. 

Johnston, C.S. and Bowling, D.L. 2002. Stability of ascorbic acid in commercially available orange juices. J. Am. Diet. Assoc. 102, 525-529. 

Kirby, C. J. Whittle, C. J. Rigby, N. Coxon, D. T. Law, B. A., Stabilization of ascorbic-acid by micro-encapsulation in liposomes. International Journal of Food Science and Technology (1991) 26,437-449. 

When the tissues of many fruits and vegetables are damaged by mechanical means, there is a rapid oxidation of ascorbic acid with others this treatment has little or no effect (Zilva, 1934 Barron et at., 1936). Stone (1937) discussed the cause of the stability of ascorbic acid in some and its instability in others and concluded that differences between various plants were due to the presence or absence of oxidase enzymes. 

Fewer studies have been made with man and they have, of necessity, been confined to the influence of dietary flavonoid supplements on blood and urinary ascorbic acid. A weakness of such studies is that the diet of most subjects contains a substantial amount of flavonoid material — even when obvious sources such as citrus fruits are excluded from the diet. This makes difficult the inclusion of a control group and also reduces the significance of additional flavonoid supplements. Nevertheless, there is some evidence that flavonoids may modify the absorption—retention—stability of ascorbic acid in man. 

Downer, A. W. E. 1942. The stability of ascorbic acid in citrus fruit juice products. J. hoc. Chem. Ind. 61, 80-82. 

Schweinzer, E., Waeg, G., Esterbauer, H. and Goldenberg, H., 1993, No enzymatic activities are necessary for the stabilization of ascorbic acid by K-562 cells, FEBS Lett. 334 106-108. 

Proot, P., De Pourcq, L., and Raymakers, A. A., 1994, Stability of ascorbic acid in a standard total parenteral nutrition mixture, Clin. Nutr. 13 273-279. 

The stability of ascorbic acid in plant products is very important in the food industry. Oxidation in milk is accelerated by copper and sunlight. Low-temperature storage of foods (below 42 F.) is helpful in preventing loss. 

GW Comstock, EP Norkus, SC Hoffman, MW Xu, KJ Helzlsouer. Stability of ascorbic acid, carotenoids, retinol, and tocopherols in plasma stored at —70 degrees C for 4 years. Cancer Epidemiol Biomarkers Prev 4 505-507, 1995. 

Capillary zone electrophoresis has been applied for measurement of ascorbic acid from fmits (58-60), serum and urine (60), cerebrospinal fluid (61), pharmaceuticals (58,62), plant tissues (63), and rat brain (97). Phosphate or borate are used as running buffers. The pH of the buffer is usually 5 to 9 to achieve the ionization of ascorbic acid. However, the degradation of ascorbic acid at alkaline pH might occur. To prevent that, L-cysteine has been added as an antioxidant for stabilization of ascorbic acid in running buffer (62,98). Sample pretreatment with either MPA or TCA was performed. 

KL Khanduja, A Koul. Stabilization of ascorbic acid in plasma. Clin Chim Acta 174 351-352, 1988. 

SA Margolis, TP Davis. Stabilization of ascorbic acid in human plasma, and its liquid chromatographic measurement. CUn Chem 34 2217-2223, 1988. 

If fresh products are held at the appropriate temperature and consumed in a short period of time, they have more vitamin C than commercially canned products. Vitamin C degrades rapidly after harvest and its amount depends on the commodity, temperature, pH and other factors. During storage (and processing), the stability of ascorbic acid is higher in fruits that have lower pH than vegetables. For example, the effect of storage on the vitamin C content in... 

Ponting (19) studied the stability of ascorbic acid in extracts prepared from plant tissues by 13 different acids. He found oxalic and metaphosphoric acids far superior to any of the other acids and about equal in their capacity to preserve ascorbic acid. Good results were obtained with 0.4% oxalic acid and 1% metaphosphoric acid in the presence of added copper. 

STUDIES USING ASCORBIC ACID 18.13.1 Stability of ascorbic acid solutions... 

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