Quantitative analysis of vitamin C in food products Essay

There is growing evidence that Vitamin C serves as a potent antioxidant in vitro. There are many functions that Vitamin C has in the body among which is the capacity to improve the immunity system much(prenominal) that a person is more than able to fight off colds and flus. Pre-Lab inclination five other functions of Vitamin C in the human body. Vitamin C is another(prenominal) name for ascorbic astringent. There is a marked similarity between the anatomical structure of glucose and Vitamin C. As a matter of fact, plants and most animals are able to synthesize Vitamin C from glucose.Unfortunately, humans are unable to do this and we must take on Vitamin C in our diet or we risk a vitamin deficiency disease. We all recognize citrus fruits as a valuable vitamin C source, but few of us realize that many freshly harvested vegs transport considerably more of this vitamin than do oranges or lime. Unfortunately, storage and processing disgrace most of the Vitamin C in vegetables before they reach the consumer. Consumer cooking methods throw out decrease the amount of vitamin C in vegetables.Vitamin C is water alcohol-soluble and thus leaches out while cooking or steaming. One expedient analytical method for measuring the Vitamin C content of a vegetable or fruit involves an oxidization-reduction titration of ascorbic venereal disease. In the titration, ascorbic acid is oxidized to corpse dehydroascorbic acid. You might think it unusual to oxidize the acid rather than measure it with a base. However, biological renders contain many substances that excessively act as acids (as was mentioned in Experiment 3) and thus interfere in a titration of ascorbic acid with a base.In contrast, many fewer components of biological materials interfere with the oxidation of ascorbic acid by the oxidizing agent 2, 6-dichloroindophenol (DCP). Thus, an oxidation-reduction titration of ascorbic acid with DCP provides a more selective analysis than would an acid-base tit ration. Please note the equation for the reaction below C6H8O6 ( neutral) + C12H7O2NCl2(red) (pH3) C6H6O6 (Colorless) + C12H9O2NCl2 (colorless) This titration is particularly convenient because DCP also serves as its own indicator.As we render DCP solution to a solution containing Vitamin C, the reaction mixture remains colorless until all of the Vitamin C has been converted to dehydroascorbic acid. The next drop of DCP solution added imparts a red color from excess DCP to the mixture, indicating both the equivalence point and the terminal figure of the titration. (Expect solution to go from red to colorless then at the expiration red again). Because DCP solutions have a relatively short shelf life, we commonly standardize such solutions immediately prior to using them.We can coiffe the standardization conveniently by titrating aliquots of an ascorbic acid solution prepared from an accurately-weighed sample of reagent-grade ascorbic acid. The standardization titration reaction is the same as the analysis reaction above. In this experiment, you bequeath begin by standardizing a DCP solution. Then you will reconcile the vitamin C content of liquid and solid food samples by titration with the regularise DCP solution.Prior to performing the titrations, you will treat the food samples with metaphosphoric acid. Treatment with this acid serves to denature and precipitate proteins that would otherwise interfere with the analysis. Acidification of thesample also serves to stabilize the ascorbic acid, which will otherwise decompose and be undetectable. Acidification to pH less than 4 also minimizes reaction of DCP with other compounds which react with DCP only at pH levels great than 4.