Determination of Vitamin C (Ascorbic Acid) Contents in Vegetable Samples by UV-Spectrophotometry and Redox Titration Methods and Estimation the Effect of Time, Cooking and Frozen on Ascorbic Acid Contents

Intisar El Sharaa, Samira Ali Ben Mussa

Abstract


The concentrations of Vitamin C, also known as L-ascorbic acid, in twenty two different types of fresh vegetables were determined by spectrophotometric and Back Redox Titration methods. The effects of some conditions such as time, cooking and frozen on the Vitamin C contents were studied. The samples were collected from different markets in Benghazi city from different places. Each sample or a part of it was weighed, squeezed in a juicer machine and centrifuged, the volume and the weight of the supernatant liquid were taken. The supernatant liquid was homogenized with 5% metaphosphoric acid-10% acetic acid solution. The ascorbic acid was oxidized to dehydroascorbic acid by bromine water in presence of acetic acid and the excess of bromine was removed by a few drops of 10% thiourea . A coupling was done with 2,4-dinitrophenyl hydrazine by putting the solution in a water bath at 37°C temperature for three hours, it was cooled in an ice bath and was treated with chilled 85% H2SO4 .  A red colour complex was produced and the absorbance was measured spectrophotometrically at 521 nm. Beer’s law was obeyed. Another method for the determination of ascorbic acid was done by an iodimetric back-titration in which an excess measured amount of iodine was generated in the sample and then the unreacted iodine was titrated with a standard solution of sodium thiosulfate. The estimation of ascorbic acid contents was done for fresh, after 4 and 7 days, cooking and frozen samples.


Keywords


Vitamin C, Vegetables, Spectrophotometry, An Iodimetric Back-Titration

Full Text:

PDF

References


Li Y, Schellhorn HE. New developments and novel therapeutic perspectives for vitamin C. J Nutr 2007;137:2171-84Carr AC, Frei B. Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am J Clin Nutr 1999;69:1086-107.

Frei B, England L, Ames BN. Ascorbate is an outstanding antioxidant in human blood plasma. Proc Natl Acad Sci U S A 1989;86:6377-81. Jacob RA, Sotoudeh G. Vitamin C function and status in chronic disease. Nutr Clin Care 2002;5:66-74.

Gershoff SN. Vitamin C (ascorbic acid): new roles, new requirements? Nutr Rev 1993;51:313-26Weinstein M, Babyn P, Zlotkin S. An orange a day keeps the doctor away: scurvy in the year 2000. Pediatrics 2001;108:E55

Tee ES, Mohd Ismail N, MohdNasir A &Kahtijah I (1997). Nutrient composition of Malayisan foods, 4th Edition, Malaysian Food Composition Database Programme, Institute for Medical Research, Kuala Lumpur; 310 p.

Levine M, Rumsey SC, Dhariwal KR, Park J & Wang Y (1999) Criteria and recommendation for ascorbic acid intake. J Amer Med Assoc 281: 1415-1423.

Verma, K. K., Jain, A., Sahasrabuddhey, B., Gupta, K., Mishra, S. (1996). Solid-phase extraction clean-up for determining ascorbic acid and dehydroascorbic acid by titration with 2,6-dichlorophenolindophenol. Journal of AOAC International,79, 1236.

Xia, W., Yuxia, D., Changxia, S., Jinghe, Y., Yuebo, W., Shuna, S. (2003). Fluorimetric determination of ascorbic acid with o-phenylenediamine. Talanta59, 95-99.

Rahman Khan M.M., Rahman M.M., Islam M.S., Begum S.A. (2006). A simple UV-spectrophotometric method for the determination of vitamin C content in various fruits and vegetables at Sylhet area in Bangladesh. Journal of Biological Sciences, 6, 388-392.

Nyyssönen, K., Salonen, J. T., Parviainen, M. T. (2000). Ascorbic acid, in modern chromatographic analysis of vitamins (3rd Ed.)

Casella, L., Gullotti, M., Marchesini, M., Petrarulo, M. (2006). Rapid enzymatic method for vitamin C assay in fruits and vegetables using peroxidase, Journal of Food Science,54, 374




DOI: http://dx.doi.org/10.52155/ijpsat.v15.2.1144

Refbacks

  • There are currently no refbacks.


Copyright (c) 2019 Intisar El Sharaa, Samira Ali Ben Mussa

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.